Publicaciones Internacionales 2012



Cannela AP; Lin JC; Liang L; Atluri V; Gotuzzo E; Felgner PL; Tsolis RM; Vinetz JM.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Serial kinetics of the antibody response against the complete Brucella melitensis ORFeome in focal vertebral Brucellosis.


 J Clin Microbiol. 2012 Jan 4. [Epub ahead of print]  


Abstract : Human brucellosis is a common zoonosis worldwide. Here we present a case of focal vertebral brucellosis in a 71-year-old Mexican-American woman who contracted infection from unpasteurized goat milk. Standard agglutination serology was negative; the diagnosis was established by isolation of Brucella melitensis from abscess fluid. A B. melitensis protein microarray comprised of nearly all proteins encoded by the bacterial genome was used to determine the kinetics of this patient's antibody responses to the complete ORFeome. Three patterns of antibody responses against B. melitensis antigens were seen on serum samples obtained on days 0 (pre-treatment), 14, 49, 100 and 180 days: 1) stable titers over time; 2) steady fall in titers; and 3) initial rise in titers followed by declining titers. Sera from this patient with chronic brucellosis recognized some of the same B. melitensis proteins as those with acute/subacute, blood culture positive brucellosis patients, but also a distinct set of proteins. This study is the first to determine the kinetics of the human antibody responses to the complete repertoire of proteins encoded by a bacterial genome, and demonstrates fundamentally different immunopathogenetic mechanisms between acute and chronic human brucellosis. While extension of these findings to a larger patient population is necessary, these findings have important clinical and diagnostic implications and lead towards new insights into the fundamental immunopathogenesis of brucellosis.




Einsiedel Ll; Fernandes L; Spelman T; Steinfort D; Gotuzzo E.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Bronchiectasis is associated with human T-Lymphotropic virus 1 infection in an indigenous Australian population.


Clin Infect Dis. 2012 Jan 54(1):43-50. [Epub 2011 Nov. 7]  


Abstract: BACKGROUND: Recent studies suggest that infection with human T-lymphotropic virus 1 (HTLV-1) might be associated with bronchiectasis among IndigenousAustralians. The present study compared the clinical characteristics and outcomes of bronchiectasis in this population, according to HTLV-1 serologic status. METHODS: We performed a retrospective cohort study of Indigenous adults with bronchiectasis and known HTLV-1 serologic status admitted to Alice Springs Hospital, central Australia, from January 2000 through December 2006. RESULTS: Among 89 Indigenous adults whose HTLV-1 serologic status was confirmed, 52 (58.4%) were HTLV-1 seropositive. Differences between HTLV-1-seropositive and HTLV-1-seronegative groups were apparent in childhood presentations and adult outcomes. Among adults, an increasing number of bronchiectatic lobes (univariable odds ratio [OR], 1.51; 95% confidence interval [CI]; 1.03-2.20; P = .033) and the presence of ground-glass opacities at chest high-resolution computed tomography (univariable OR, 8.54; 95% CI, 1.04-70.03; P = .046) predicted HTLV-1 infection. Cor pumonale (HTLV-1-positive group, 10/52; HTLV-1-negative group, 1/37; P = .023) was more frequent among HTLV-1-seropositive adults, who also experienced a higher disease-specific mortality (univariable OR, 5.78; 95% CI, 1.17-26.75; P = .028). Only HTLV-1-seropositive patients were admitted specifically for the treatment of infected skin lesions, and this finding predicted death (multivariable OR, 6.77; 95% CI, 1.46-31.34; P = .014). Overall mortality was high; 34.2% of the cohort died at a median age of 42.5 years. CONCLUSIONS: HTLV-1 infection contributes to the risk of developing bronchiectasis and worsens outcomes among Indigenous Australians



Veland N; Boggild A; Valencia C; Valencia B; Llanos-Cuentas A; Van der Auwera G; Dujardin JC; Arevalo J.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

 Leishmania (Viannia) species identification on clinical samples from cutaneous leishmaniasis patients in Peru: Assessment of a molecular stepwise approach.


Journal of Clinical Microbiology 2012, 50(2):495-498.

Abstract: We present an algorithm based on three PCR assays for Leishmania (Viannia) species identification and assessed its performance using 70 specimens from Peruvianpatients. The succession of the assayed targets can be ordered according to species prevalence. Sequential progression through the algorithm reduced the number of samples here studied by approximately 30% after each step.



Sattui S; de la Flor C; Sanchez C; Lewis D; Lopez G; Rizo-Patrón E; White AC Jr; Montes M.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

 Cryopreservation modulates the detection of regulatory T cell markers.


Cyrometry B Clin Cytom. 2012, Jan;82(1):54-8.

Abstract: BACKGROUND: Regulatory T cells (Tregs) modulate the host response in infectious diseases and are key mediators of peripheral tolerance. Cryopreservation of peripheral blood mononuclear cells (PBMCs) is commonly used in immunological field studies where access to complex laboratory tests is not feasible. Our objective is to assess the effects of cryopreservation on the flow cytometric detection of surface and intracellular markers of Tregs. METHODS: Heparinized venous blood was obtained from 36 healthy individuals and 15 HIV-1 infected subjects. PBMCs were isolated and stained for surface and intracellular markers of Tregs. PBMCs from each subject were cryopreserved in liquid nitrogen with DMSO; these cells were thawed and stained at a later date. All samples were analyzed by flow cytometry. The proportion of Tregs was compared using Wilcoxon signed-rank test. RESULTS: Cryopreservation decreased the proportion of Tregs identified by surface and intracellular markers in healthy individuals and in HIV-1 patients. The proportion of CD4+CD25+FoxP3+ was decreased from 3.13 to 2.16% (P < 0.001) for non-HIV subjects and from 2.68 to 0.94% (P < 0.001) for HIV subjects, compared to fresh samples. Significant reduction was also observed for CD4+CD25+CD127lo-neg. However, the effect varied considerably between samples. The effect was similar among HIV and non-HIV patients (P = 0.38). CONCLUSIONS: Cryopreservation modulates the detection of surface and intracellular markersof Tregs. These results confirm that research on Tregs, including studies of HIV-1 infected patients, should be carried out prospectively on fresh samples in order to obtain unbiased conclusions. Results using cryopreserved cells should be regarded as only preliminary.



Yalcindag E; Elguero E; Arnathau C; Durand P; Akiana J; Anderson T; Aubouy A; Balloux F; Besnard P; Bogreau H; Carnevale P; D’Alessandro U; Fontenille D; Gamboa D;Jombart T; Le Mire J; Leroy E; Maestre A; Mayxay M; Menard D; Musset L; Newton P; Nkoghe D; Noya O; Ollomo B; Rogier Ch; Veron V; Wide A; Zakeri S; Carme B; Legrand E; Chevillon Ch; Ayala F; Renaud F; Prugnolle F.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

 Multiple independet introductions of Plasmodium falciparum in South America.


PNAS. 2012, Jan 10;109(2):511-516.


Abstract: The origin of Plasmodium falciparum in South America is controversial. Some studies suggest a recent introduction during the European colonizations and the transatlantic slave trade. Other evidence-archeological and genetic-suggests a much older origin. We collected and analyzed P. falciparum isolates from different regions of the world, encompassing the distribution range of the parasite, including populations from sub-Saharan Africa, the Middle East, Southeast Asia, and South America. Analyses of microsatellite and SNP polymorphisms show that the populations of P. falciparum in South America are subdivided in two main genetic clusters (northern and southern). Phylogenetic analyses, as well as Approximate Bayesian Computation methods suggest independent introductions of the two clusters from African sources. Our estimates of divergence time between the South American populations and their likely sources favor a likely introduction from Africa during the transatlantic slave trade.



Pfeiffer ML; Dupont HL; Ochoa TJ.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

The patient presenting with acute dysentery – A systematic review.


J Infect. 2012 Jan 13. [Epub ahead of print]



Abstract: OBJECTIVES: The etiologies, clinical presentations and diagnosis of acute pathogen-specific dysentery in children and adults in industrialized and developing regions is described to help develop recommendations for therapy. METHODS: We conducted a systematic review of literature published between January 2000 and June 2011 to determine the frequency of occurrence of pathogen-specific dysentery. RESULTS: Shigella, Salmonella, and Campylobacter remain the most frequent bacterial causes ofdysentery worldwide. Shiga toxin-producing Escherichiacoli (STEC) is potentially important in industrialized countries. Entamoebahistolytica must be considered in the developing world, particularly in rural or periurban areas. Clinicians should use epidemiological clues and knowledge of endemicity to suspect Vibrio spp., Aeromonas spp., Plesiomonas spp., Yersinia enterocolitica, Clostridiumdifficile, Cytomegalovirus or Schistosoma mansoni in cases presenting with dysentery. A single fecal sample studied for etiologic agents is the customary way to make an etiologic diagnosis. CONCLUSIONS: While a majority of dysenteric cases will not have an identifiable agent causing the illness, when an etiologic organism is identified, other than STEC, each has a specific recommended form of therapy, which is provided in this review.



Talledo M; López G; Huyghe JR; Verdonck K; González E; Clark D; Vanham G; Gotuzzo E; Van Camp G; Van Laer L.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

 Possible implication of NKFB1A and NKG2D genes in susceptibility to HTLV-1-associated myelopathy/tropical spastic paraparesis in Peruvian patients infected with HTLV-1.


J Med Virol. 2012 Feb;84(2):319-26.


Abstract:The human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a progressive disease causing paraparesis of the lower limbs. Only a minority of persons infected with HTLV-1 develop HAM/TSP. Universal susceptibility factors for HAM/TSP are not known. The viral genotype is similar in asymptomatic carriers and HAM/TSP patients. High proviral load has been associated consistently with HAM/TSP, but this factor does not explain fully the presence of disease in HTLV-1-infected subjects. Most likely, host genetic factors will play an important role in HAM/TSP development. A two-stage case-control study was carried out to evaluate the association between HAM/TSP and candidate single nucleotide polymorphisms (SNPs) from 45 genes in addition to six human leukocyte antigen (HLA) alleles. Ancestry-informative markers were used to correct for population stratification. Several SNPs belonging to NFKB1A and NKG2Dshowed a trend of association in both stages. The fact that the direction of the association observed in the first stage was the same in the second stage suggests that NFKB1A andNKG2D may be implicated in the development of HAM/TSP. Further replication studies in independent HTLV-1 patient groups should validate further these associations.



Buonfrate D; Angheben A; Gobbi F; Muñoz J; Requena-Mendez A; Gotuzzo E; Mena MA; Bisoffi Z.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

 Imported Strongyloidiasis: epidemiology, presentations, and treatment.


Curr Infect Dis Rep. 2012 Feb 11. [Epub ahead of print]


Abstract: Strongyloidiasis is extremely more frequent in immigrants than in travellers. Clinical presentations do not differ significantly between the two groups, and the most frequent picture is a chronic infection characterized by intermittent, mild, non-specific symptoms. Acute presentation is rare but it has been reported in travellers. Screening of asymptomatic subjects is not generally recommended, while a presumptive treatment with ivermectin might be justified for all travellers and immigrant patients presenting unexplained eosinophilia and/or compatible symptoms, even in case of negative test results. In fact, delayed diagnosis and treatment has life-threatening consequences in patients with conditions predisposing to development of hyperinfection and dissemination.



León M; Alave J; Bustamante B; Gotuzzo E; Seas C.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Letter to the editor : A probable association between HTLV-1 and endemic micosis in Latin America.


J Infect Dev Ctries 2012; 6(3):301.




Seas C; Villaverde H; Maguiña C.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Images in clinical tropical medicine: A 60-year-old man from the highlands of Peru with fever and hemolysis.


Am J Trop Med Hyg. 2012; 86(3):381.




Ochoa TJ; Pezo A; Cruz K; Chea-Woo E; Cleary TG.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Clinical studies of lactoferrin in children (1) (1) this article is part of a special issue entitled lactoferrin and has undergone the Journal’s usual peer review process.


Biochem Cell Biol. 2012 Mar 1. [Epub ahead of print]


Abstract : Much has been learned in recent years about the mechanisms by which breastfeeding improves child health and survival. However, there has been little progress in using these insights to improve pediatric care. The aim of this study was to review all clinical studies of lactoferrin (LF) in children in an effort to determine which interventions may improve pediatric care or require further research. We conducted a systematic and critical review of published literature and found 19 clinical studies that have used human or bovine LF for different outcomes: iron metabolisms and anemia (6 studies), fecal flora (5 studies), enteric infections (3 studies), common pediatric illnesses (1 study), immunomodulation (3 studies), and neonatal sepsis (1 study). Although the efficacies have varied in each trial, the main finding of all published studies is the safety of the intervention. Protection against enteric infections and neonatal sepsis are the most likely biologically relevant activities of LF in children. Future studies on neonatal sepsis should answer critically important questions. If the data from these sepsis studies are proven to be correct, it will profoundly affect the treatment of low birth weight neonates and will aid in the reduction of child mortality worldwide.




Lee S; Shin Y; Clark D; Gotuzzo E; Levin MC.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Cross-reactive antibodies to target proteins are dependent upon oligomannose glycosylated epitopes in HTLV-1 associated neurological disease.


 J Clin Immunol. 2012 Mar 6. [Epub ahead of print]


Abstract : Our lab recently identified a cross-reactive antibody response between human T-lymphotropic virus type-1-p24-(gag) (HTLV-1-p24-(gag)) and peroxiredoxin-1 (PrX-1) as potentially contributing to the pathogenesis of HTLV-1 associated neurological disease via molecular mimicry. These targets proteins were glycosylated, yet the glycan side chains immunoreactive with the immunoglobulins were unknown. Using a combination of lectin isolation and serial enzymatic deglycosylation of glycoproteins, we determined that the immunoreactive epitopes contained branched oligomannose side chains. These data suggest that post-translational glycosylation specifically related tooligomannose immunoreactivity to both the infecting and host antigens may contribute to molecular mimicry and be important in the pathogenesis of HTLV-1 associatedneurological disease.




Mosquito S; Zegarra G; Villanueva C; Ruiz J; Ochoa TJ.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Effect of bovine lactoferrin on the minimum inhibitory concentrations of ampicillin and trimethoprim-sulfamethoxazole for clinical Shigella spp. Strains (1) (1) This article is aprt of a special issue entitled lactoferrin and has undergone the Journal’s usual peer review process.


Biochem Cell Biol. 2012 Mar 7. [Epub ahead of print]


Abstract : Here, we determined the effect of bovine lactoferrin (bLF) on the minimum inhibitory concentration (MIC) of ampicillin and trimethoprim-sulfamethoxazole in Shigella . Using a microdilution method, the MIC was determined in the presence or absence of bovine lactoferrin (10 mg/mL) on 88 Shigella strains (56 Shigella flexneri , 15 Shigella boydii , 13 Shigella sonnei , and 4 Shigella dysenteriae ) previously isolated from peruvian children <2 years old. A fold change of 2 or more in MIC values was considered significant. For ampicillin, 67 (76%) strains were highly resistant; one-third of the strains (32%) showed a decrease in ampicillin MIC in the presence of LF. This was more typical of MIC values in less resistant strains. For 7 (8%) ampicillin-resistant strains, the decrease in the MIC resulted in the strains reaching the cutoff for susceptible in the presence of bLF. For trimethoprim-sulfamethoxazole, 93% of the isolates (n = 82) were highly resistant and only 4 isolates (5%) decreased their MIC in the presence of bLF. None of the trimethoprim-sulfamethoxazole resistant strains became susceptible in the presence of LF. The decrease in the MIC in the presence of bLF seems to depend on the mechanisms of action of each antibiotic. In vivo studies are needed to further evaluate bLF as a coadjuvant to antibiotic treatment of resistant Shigella.



Garcia C; Horna G; Linares E; Ramírez R; Tapia E; Velásquez J; Medina V; Guevara J; Urbina M; Zevallos S; Espinoza N; Samalvides F; Jacobs J.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Letter : Antimicrobial drug resistance in Peru.


Emerging Infectious Diseases. 2012; Mar. 18(3)





Chuquiyauri R; Paredes M; Peñataro P; Torres S; Marin S; Tenorio A; Brouwer KC; Abeles S; Llanos-Cuentas A; Gilman RH; Kosek M; Vinetz JM.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Socio-demographics and the development of malaria elimination strategies in the low transmission setting.


Acta Trop. 2012 Mar; 121(3):292-302.


Abstract: This analysis presents a comprehensive description of malaria burden and risk factors in Peruvian Amazon villages where malaria transmission is hypoendemic. More than 9000 subjects were studied in contrasting village settings within the Department of Loreto, Peru, where most malaria occurs in the country. Plasmodium vivax is responsible for more than 75% of malaria cases; severe disease from any form of malaria is uncommon and death rare. The association between lifetime malaria episodes and individual and household covariates was studied using polychotomous logistic regression analysis, assessing effects on odds of some vs. no lifetime malaria episodes. Malariamorbidity during lifetime was strongly associated with age, logging, farming, travel history, and living with a logger or agriculturist. Select groups of adults, particularly loggers and agriculturists acquire multiple malaria infections in transmission settings outside of the main domicile, and may be mobile human reservoirs by which malaria parasites move within and between micro-regions within malaria endemic settings. For example, such individuals might well be reservoirs of transmission by introducing or reintroducingmalaria into their home villages and their own households, depending on vector ecology and the local village setting. Therefore, socio-demographic studies can identify people with the epidemiological characteristic of transmission risk, and these individuals would be prime targets against which to deploy transmission blocking strategies along with insecticide treated bednets and chemoprophylaxis.




Rivera FP; Sotelo E; Morales I; Menacho F; Medina AM; Evaristo R; Valencia R; carbajal L; Ruiz J; Ochoa TJ.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Short communication: detection of shiga toxin-producing Escherichia coli (STEC) in healthy cattle and pigs in Lima, Peru.


J Dairy Sci. 2012 Mar; 95(3):1166-9.


Abstract : The aim of this study was to determine the prevalence of Shiga toxin-producing Escherichia coli (STEC) in cattle and pigs as a possible STEC reservoir in Lima,Peru. One hundred and fourteen cattle and 112 pigs from 10 and 4 farms, respectively, were studied. Five E. coli colonies per culture were studied by a multiplex real-time PCR to identify Shiga toxin-producing (stx1, stx2, eaeA), enterotoxigenic (lt, st), enteropathogenic (eaeA), enteroinvasive (ipaH), enteroaggregative (aggR), and diffusely adherent E. coli (daaD). Shiga toxin-producing E. coli were isolated from 16 cattle (14%) but none from pigs. stx1 was found in all bovine isolates, 11 of which also carried eaeA genes (69%); only 1 sample had both stx1 and stx2. Thirteen stx-positive strains were classified as Shiga-toxigenic (81%) using an enzymatic immunoassay, 2 STEC strains were from serogroup O157 (13%), and 7 were sorbitol negative (44%). Enteropathogenic E. coli were detected more frequently in cattle (18%, 20/114) than in pigs (5%, 6/112). To our knowledge, this is the first study on the prevalence of STEC in farms animals in Peru using molecular methods. Further studies are needed in a large number of farms to determine the relevance of these findings and its consequences for public health.



Llanos A; Lee J; López F; Contreras C; Barletta F; Chea-Woo E; Ugarte C; Cleary TG; Ochoa TJ.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Shiga toxin-producing Escherichia coli in Peruvian children with bloody diarrhea.


Pediatr Infect Dis J. 2012 Mar;31(3):314-6.


Abstract: Shiga toxin-producing Escherichia coli (STEC) is not routinely sought in clinical laboratories in developing counties. Among 131 bloody diarrhea samples in Peruvian children <5 years of age, STEC was found in 9.2% and was associated with absence of fever, an observation that may increase suspicion of these pathogens. Because of the significant prevalence of STEC locally, proper diagnostics methods should be implemented in the region.




Da Silva-Nunes M; Moreno M; Conn JE; Gamboa D; Abeles S; Vinetz JM; Ferreira MU.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Amazonian malaria: asymptomatic human reservoirs, diagnostic challenges, environmentally driven changes in mosquito vector populations, and the mandate for sustainable control strategies.


Acta Trop. 2012 Mar; 12(3):281-91.


Abstract : Across the Americas and the Caribbean, nearly 561,000 slide-confirmed malaria infections were reported officially in 2008. The nine Amazonian countries accounted for 89% of these infections; Brazil and Peru alone contributed 56% and 7% of them, respectively. Local populations of the relatively neglected parasite Plasmodium vivax, which currently accounts for 77% of the regional malaria burden, are extremely diverse genetically and geographically structured. At a time when malaria elimination is placed on the public health agenda of several endemic countries, it remains unclear why malaria proved so difficult to control in areas of relatively low levels of transmission such as the Amazon Basin. We hypothesize that asymptomatic parasite carriage and massive environmental changes that affect vector abundance and behavior are major contributors to malaria transmission in epidemiologically diverse areas across the Amazon Basin. Here we review available data supporting this hypothesis and discuss their implications for current and future malaria intervention policies in the region. Given that locally generated scientific evidence is urgently required to support malaria control interventions in Amazonia, we briefly describe the aims of our current field-oriented malaria research in rural villages and gold-mining enclaves in Peru and a recently opened agricultural settlement in Brazil.


Reyes-Uribe P; Pereira-Dos santos T; De Jesus JB; Mesquita-Rodrigues C; Arevalo J; Cupolillo E; Cuervo P.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Comparative zymographic analysis of metallopeptidase of Leishmania (Viannia) peruviana and Leishmania (Viannia) braziliensis isolates from Peru.


Parasitol Int. 2012 mar 30. [Epub ahead of print].


Abstract : American tegumentary leishmaniasis (ATL) in Peru is mainly associated with Leishmania (Viannia) peruviana and L. (V.) braziliensis. These parasites are genetically related, and their characterization as distinct species is controversial. Despite their genetic similarity, each species is associated with different clinical manifestations of ATL; L. (V.) peruviana causes only cutaneous leishmaniasis, whereas L. (V.) braziliensis can cause both cutaneous and mucocutaneous leishmaniasis. Because the primary cutaneous lesions caused by infection with these species are indistinguishable, it is necessary to develop a suitable method to differentiate them in order to prevent possible metastasis to oropharyngeal mucosa. In the present study, we investigated the proteolytic profile of L. (V.) peruviana and L. (V.) braziliensis isolates from Peru by zymographicanalysis in SDS-PAGE copolymerized with gelatin. Enzymes were characterized according to their pH range of activity and sensitivity to distinct peptidase inhibitors. We observed that L. (V.) peruviana isolates displayed three proteolytic bands with molecular masses ranging from 55 to 80kDa, whereas L. (V.) braziliensis isolates showed six proteolytic activities between 55 and 130kDa. Using specific inhibitors, we determined that these proteolytic activities are due to metallopeptidases and present optimal activity between the pH range 5.5 and 10.0. Our results suggest that the expression of metallopeptidases in L. (V.) peruviana and L. (V.) braziliensis isolates from Peru is species-specific.




Kosek M; Yori PP; Gilman RH; Calderon M; Zimic M; Chuquiyauri R; Jeri C; Pinedo-Cancino V; Matthias MA; Llanos-Cuentas A; Vinetz JM.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

High degree of plasmodium vivax diversity in the Peruvian amazon demonstrated by Tandem repeat polymorphism analysis.


Am J Trop Med Hyg. 2012 Apr; 86(4):580-6.


Abstract: Molecular tools to distinguish strains of Plasmodium vivax are important for studying the epidemiology of malaria transmission. Two sets of markers-tandem repeat(TR) polymorphisms and MSP3α-were used to study Plasmodium vivax in patients in the Peruvian Amazon region of Iquitos. Of 110 patients, 90 distinct haplotypes were distinguished using 9 TR markers. An MSP3α polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using HhaI and AluI revealed 8 and 9 profiles, respectively, and 36 profiles when analyzed in combination. Combining TR and PCR-RFLP markers, 101 distinct molecular profiles were distinguished among these 110 patients. Nine TR markers arrayed along a 100 kB stretch of a P. vivax chromosome containing the gene for circumsporozoite protein showed non-linear linkage disequilibrium (I(SA) = 0.03, P = 0.001). These findings demonstrate the potential use of TR markers for molecular epidemiology studies.




Contreras CA; Ochoa TJ; Ruiz J; Lacher DW; Durand D; Debroy C; Lanata CF; Cleary TG.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Genetic diversity of LEE genes of enteropathogenic Escherichia coli (EPEC) isolated from Peruvian children.


J Med Microbiol. 2012 Apr 5. [Epub ahead of print]


Abstract :The aim of this study was to determine the frequency and allele-associations of LEE encoded esp and tir genes among 181 EPEC strains (90 diarrhea-associated and 91 controls) isolated from Peruvian children less than 18 months of age. We have analyzed espA, espB, espD and tir alleles by PCR-RFLP. EPEC strains were isolated with higher frequency from healthy controls (92/424, 21.7%) than from diarrheal samples (90/936, 9.6%) (p< 0.001); 28.9% of diarrheal and 17.6% of control samples were typicalEPEC (tEPEC). The distribution of espA-alleles (alpha, beta, beta2 and gamma) and espD-alleles (alpha, beta, gamma and a new variant, espD-N1) between tEPEC and atypicalEPEC (aEPEC) was significantly different (p< 0.05). espD-alpha was more common among acute episodes (p<0.05). espB typing resulted in five alleles (alpha, beta, gamma and two new sub-alleles espB-alpha2 and espB-alpha3 ), while tir-beta and tir-gamma2 were the most common intimin receptor subtypes. Seventy two combinations of espA, espB, espD and tir alleles were found; the most prevalent combination was espA-beta, espB-beta, espD-beta, tir-beta (34/181 strains), which was more frequent among tEPEC strains (p<0.05). Our findings indicate that there is high degree of heterogeneity among EPEC strains isolated from Peruvian children and that aEPEC and tEPEC variants cluster.




Tello R; Terashima A; Marcos LA; Machicado J; Canales M; Gotuzzo E.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Highly effective and inexpensive parasitological technique for diagnosis of intestinal parasites in developing countries: spontaneous sedimentation technique in tube.


Int J Infect Dis. 2012 Apr 10. [Epub ahead of print]


Abstract : Millions of low-income people in the world are affected by intestinal parasites. Inexpensive, simple, and effective techniques for diagnosis are necessary. Thespontaneous sedimentation technique in tube (SSTT), for application in poor healthcare settings and under field-work conditions, was described 25 years ago in Peru by Tello. The advantages of the SSTT are its ability to detect the majority of intestinal parasites, including eggs, larvae, cysts, and trophozoites, and its low cost.




Odiwuor S; Veland N; Maes I; Arévalo J; Dujardin JC; Van der Auwera G. Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Evolution of the Leishmania braziliensis species complex from amplified fragment length polymorphisms, and clinical implications.


 Infect Genet Evol. 2012 Apr 10. [Epub ahead of print]


Abstract : In order to get more insight into its evolution and geographical distribution, we investigated the Leishmania (Viannia) braziliensis species complex using amplifiedfragment length polymorphisms and sequencing of a heat-shock protein 70 gene fragment. Previously, several assays had alluded to the high genetic diversity of the group, and single-locus assays typically identified two species, i.e. L. braziliensis and Leishmania peruviana, with occasional genetic signatures of both in the same strain. By analysis of 53 parasite isolates from Peru, and eight additional ones from other countries, we identified an atypical L. braziliensis cluster, and confirmed the origin of L. peruviana from the L.braziliensis cluster during the colonization of the western Andean coastal valleys. We discuss the clinical and taxonomical implications of our findings in relation to currently used species typing assays.





Machicado JD; Marcos LA; Tello R; Canales M; Terashima A; Gotuzzo E. Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Diagnosis of soil-transmitted helminthiasis in an Amazonic community of Peru using multiple diagnostic techniques.


 Trans R Soc Trop Med Hyg. 2012 Apr 17. [Epub ahead of print]


Abstract : An observational descriptive study was conducted in a Shipibo-Conibo/Ese'Eja community of the rainforest in Peru to compare the Kato-Katz method and the spontaneous sedimentation in tube technique (SSTT) for the diagnosis of intestinal parasites as well as to report the prevalence of soil-transmitted helminth (STH) infections in this area. A total of 73 stool samples were collected and analysed by several parasitological techniques, including Kato-Katz, SSTT, modified Baermann technique (MBT), agar plate culture, Harada-Mori culture and the direct smear examination. Kato-Katz and SSTT had the same rate of detection for Ascaris lumbricoides (5%), Trichuris trichiura (5%), hookworm (14%) and Hymenolepis nana (26%). The detection rate for Strongyloides stercoralis larvae was 16% by SSTT and 0% by Kato-Katz, but 18% by agar plate culture and 16% by MBT. The SSTT also had the advantage of detecting multiple intestinal protozoa such as Blastocystis hominis (40%), Giardia intestinalis (29%) and Entamoeba histolytica/E. dispar (16%). The most common intestinal parasites found in this community were B. hominis, G. intestinalis, H. nana, S. stercoralis and hookworm. In conclusion, the SSTT is not inferior to Kato-Katz for the diagnosis of common STH infections but is largely superior for detecting intestinal protozoa and S. stercoralis larvae.



Riveros M; Riccobono E; Durand D; Mosquito S; Ruiz J; Rossoloni GM; Ochoa TJ; Pallecchi L.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Plasmid-mediated quinolone resistance genes in enteroaggregative Escherichia coli from infants in Lima, Peru.


Int J Antimicrob Agents. 2012 Apr 20. [Epub ahead of print]




Halsey E; Marks M; Gotuzzo E; Fiestas V; Suarez L; Vargas J; Aguayo N; Madrid C; Vimos C; Kochel T; Laguna-Torres A.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Correlation of serotype-specific dengue virus infection with clinical manifestations.


 Plos Neglected Tropical Diseases. 2012 May 1.


Abstract: Background: Disease caused by the  dengue virus (DENV) is a significant cause of morbidity throughout the world. Although prior research has focused on the association of specific DENV serotypes (DENV-1, DENV-2, DENV-3, and DENV-4) with the development of severe outcomes such as dengue hemorrhagic fever and dengue shock syndrome, relatively little work has correlated other clinical manifestations with a particular DENV serotype. The goal of this study was to estimate and compare the prevalence of non-hemorrhagic clinical manifestations of DENV infection by serotype. Methodology and Principal Findings: Between the years 2005-2010, individuals with febrile disease from Peru, Bolivia, Ecuador, and Paraguay were enrolled in an outpatient passive surveillance study. Detailed information regarding clinical signs and symptoms, as well as demographic information, was collected. DENV infection was confirmed in patient sera with polyclonal antibodies in a culture-based immunofluorescence assay, and the infecting serotype was determined by serotype-specific monoclonal antibodies. Differences in the prevalence of individual and organ-system manifestations were compared across DENV serotypes. One thousand seven hundred and sixteen individuals were identified as being infected with DENV-1 (39.8%), DENV-2 (4.3%), DENV-3 (41.5%) or DENV-4 (14.4%). When all four DENV serotypes were compared with each other, individuals infected with DENV-3 had a higher prevalence of musculoskeletal and gastrointestinal manifestations, and individuals infected with DENV-4 had a higher prevalence of respiratory and cutaneous manifestations.



Bravo F; Seas C.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Balamuthia Mandrillaris Amoebic Encephalitis: An emerging parasitic infection.


Curr Infect Dis Rep. 2012 May 22.


Abstract:  Balamuthia mandrillaris is a free living amoeba that can be isolated from soil. It is an emerging pathogen causing skin lesions as well as CNS involvement with a fatal outcome if untreated. The infection has been described more commonly in inmunocompetent individuals, mostly males, many children, and with a predilection for population with Hispanic background in cases occurring in the United States. Except for Africa, all continents have reported the disease, although a majority of cases are seen in North and South America. In published reported cases from North America, most patients will debut with neurological symptoms, where as in countries like Peru, a skin lesion will precede other symptoms. The classical skin lesion is a plaque, mostly located on face or knee. Diagnosis requires a high level of suspicion. Therapeutic strategies require a multidrug approach, than includes at least one amebicidal drug, and prolonged periods of treatment.



Li Yang Hsu; Limin Wijaya; Shu-Ting Ng E; Gotuzzo E.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Tropical Fungal Infections.


Infect Dis Clin N Am. 2012 June 26(2):497-512.


Abstract: Fungal infections are more common and diverse in the tropics but are also increasingly seen in returning travelers and migrants as international travel becomes easier. They are conventionally classified into superficial, cutaneous, subcutaneous, and systemic mycoses. This article provides an overview of superficial, cutaneous, and subcutaneous mycoses that are more prevalent and/or geographically restricted to the tropics and briefly discusses fungal infections in returning travelers. Systematic data on such infections as travel-associated diseases are currently lacking, and enhanced surveillance for fungal infections may lead to early diagnosis and an understanding of the epidemiology of the fungal infections among travelers.



Riveros M; Riccobono E; Durand D; Mosquito S; Ruiz J; Rossolini GM; Ochoa TJ; Pallecchi L.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Plasmid-mediated quinolone resistance genes in enteroaggregative Escherichia coli from infants in Lima, Peru.


 Int J Antimicrob agents. 2012 Jun; 39(6):540-2.



Ponce M; Ugarte-Gil C; Zamudio C; Krapp F; Gotuzzo E; Seas C.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Additional evidence to support the phasing-out of treatment category II regimen for pulmonary tuberculosis in Peru.


Transactions of the Royal Society of Tropical Medicine and Hygiene 2012 June 26; 106:508-510.


Abstract: The effectiveness of the World Health Organization's (WHO) treatment category II regimen for tuberculosis in 124 patients was compared to that of 1147 patients receiving treatment category I in Lima, Peru following WHO's guidelines. Drug susceptibility test was available for 85% of patients. Prevalence of multi drug resistance and streptomycin resistance were 5.1% and 20.7%, respectively. Overall cure rate for regimen II was lower than that of regimen I: 67.8% (95% CI: 58.9-75.6.) vs 77.8% (95% CI: 75.3-80.2), p=0.014. Multi-drug resistance exerted a profound effect on cure rates in both regimens. Our results support the phasing-out of treatment category II regimen in Peru.



Moens B; Decanine D; Menezes SM; Khouri R; Silva-Santos G; Lopez G; Alvarez C; Talledo M; Gotuzzo E; de Almeida R; Galvao-Castro B; Vandamme AM; Van Weyenbergh J.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Ascorbic Acid Has superior Ex vivo Antiproliferative, Cell Death-Inducing and Immunomodulatory Effects over IFN-alfa in HTLV-1-Associated Myelopathy.


Plos Neglected Tropical Diseases 2012 July;6(7):e1729.


Abstract: Background: Clear therapeutic guidelines for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) are missing due to the lack of randomized double-blind controlled clinical trials. Moderate yet similar clinical benefit has been demonstrated for IFN-a and high-dose ascorbic acid (AA) monotherapy in a large open clinical trial. However, there is a lack of in vivo and in vitro studies exploring and comparing the effects of high-dose AA and IFN-a treatment in the context of HAM/TSP. Therefore, we performed the first comparative analysis of the ex vivo and in vitro molecular and cellular mechanisms of action of IFN-a and high-dose AA in HAM/TSP.

Principal Findings: Through thymidine incorporation and quantification of Th1/Th2/Th17 cytokines, we demonstrate that high-dose AA displays differential and superior antiproliferative and immunomodulatory effects over IFN-a in HAM/TSP PBMCs ex vivo. In addition, high-dose AA, but not IFN-a, induced cell death in both HAM/TSP PBMCs and HTLV-1-infected Tcell lines MT-2 and MT-4. Microarray data combined with pathway analysis of MT-2 cells revealed AA-induced regulation of genes associated with cell death, including miR-155. Since miR-155 has recently been demonstrated to up-regulate IFN-c, this microRNA might represent a novel therapeutic target in HAM/TSP, as recently demonstrated in multiple sclerosis, another neuroinflammatory disease. On the other hand, IFN-a selectively up-regulated antiviral and immune-related genes.

Conclusions: In comparison to IFN-a, high-dose AA treatment has superior ex vivo and in vitro cell death-inducing, antiproliferative and immunomodulatory anti-HTLV-1 effects. Differential pathway activation by both drugs opens up avenues for targeted treatment in specific patient subsets.



Moens B; Pannecouque CH; López G; Talledo M; Gotuzzo E; Khouri R; Bittencourt A; Farré L; Galvao-Castro B; Vandamme AM; Van Weyenbergh J.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Simultaneous RNA quantification of human and retroviral genomes reveals intact interferon signaling in HTLV-1-infected CD4+ T cell lines.

 Virology Journal 2012 9:171.

 ABSTRACT: BACKGROUND:  IFN-alpha contributes extensively to host immune response upon viral infection through antiviral, pro-apoptotic, antiproliferative and immunomodulatory activities. Although extensively documented in various types of human cancers and viral infections, controversy exists in the exact mechanism of action of IFN-alpha in human immunodeficiency virus type 1 (HIV-1) and human T-lymphotropic virus type 1 (HTLV-1) retroviral infections.

RESULTS: IFN-alpha displayed strong anti-HIV-1 effects in HIV-1/HTLV-1 co-infected MT-4 cells in vitro, demonstrated by the dose-dependent inhibition of the HIV-1-induced cytopathic effect (IC50 = 83.5 IU/ml, p < 0.0001) and p24 levels in cell-free supernatant (IC50 = 1.2 IU/ml, p < 0.0001). In contrast, IFN-alpha treatment did not affect cell viability or HTLV-1 viral mRNA levels in HTLV-1 mono-infected cell lines, based on flow cytometry and nCounter analysis, respectively. However, we were able to confirm the previously described post-transcriptional inhibition of HTLV-1 p19 secretion by IFN-alpha in cell lines (p = 0.0045), and extend this finding to primary Adult T cell Leukemia patient samples (p = 0.031). In addition, through microarray and nCounter analysis, we performed the first genome-wide simultaneous quantification of complete human and retroviral transciptomes, demonstrating significant transcriptional activation of interferon-stimulated genes without concomitant decrease of HTLV-1 mRNA levels.

CONCLUSIONS: Taken together, our results indicate that both the absence of in vitro antiproliferative and pro-apoptotic activity as well as the modest post-transcriptional antiviral activity of IFN-alpha against HTLV-1, were not due to a cell-intrinsic defect in IFN-alpha signalisation, but rather represents a retrovirus-specific phenomenon, considering the strong HIV-1 inhibition in co-infected cells.




Buonfrate D; Angheben A; Gobbi F; Muñoz J; Requena-Mendez A; Gotuzzo E; Mena MA; Bisoffi Z.

 Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Imported strongyloidiasis: epidemiology, presentations, and treatment.

Curr Infect Dis Rep. 2012 Jun;14(3):256-62.

Abstract: Strongyloidiasis is extremely more frequent in immigrants than in travellers. Clinical presentations do not differ significantly between the two groups, and the most frequent picture is a chronic infection characterized by intermittent, mild, non-specific symptoms. Acute presentation is rare but it has been reported in travellers. Screening of asymptomatic subjects is not generally recommended, while a presumptive treatment with ivermectin might be justified for all travellers and immigrant patients presenting unexplained eosinophilia and/or compatible symptoms, even in case of negative test results. In fact, delayed diagnosis and treatment has life-threatening consequences in patients with conditions predisposing to development of hyperinfection and dissemination.



 Carriquiry GOtero LGonzález-Lagos EZamudio CSánchez ENabeta PCampos MEchevarría JSeas CGotuzzo E.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

A Diagnostic Accuracy Study of Xpert®MTB/RIF in HIV-Positive Patients with High Clinical Suspicion of Pulmonary Tuberculosis in Lima, Peru.

PLoS One. 2012;7(9):e44626. Epub 2012 Sep 7.

ABSTRACT: BACKGROUND: Diagnosis of pulmonary tuberculosis (TB) among human immunodeficiency virus (HIV) patients remains complex and demands easy to perform and accurate tests. Xpert®MTB/RIF (MTB/RIF) is a molecular TB diagnostic test which is rapid and convenient; the test requires minimal human resources and reports results within two hours. The majority of performance studies of MTB/RIF have been performed in high HIV burden settings, thus TB diagnostic studies among HIV patients in low HIV prevalence settings such as Peru are still needed. METHODOLOGY/PRINCIPAL FINDINGS:From April 2010 to May 2011, HIV-positive patients with high clinical suspicion of TB were enrolled from two tertiary hospitals in Lima, Peru. Detection of TB by MTB/RIF was compared to a composite reference standard Löwenstein-Jensen (LJ) and liquid culture. Detection of rifampicin resistance was compared to the LJ proportion method. We included 131 patients, the median CD4 cell count was 154.5 cells/mm(3) and 45 (34.4%) had TB. For TB detection among HIV patients, sensitivity of MTB/RIF was 97.8% (95% CI 88.4-99.6) (44/45); specificity was 97.7% (95% CI 91.9-99.4) (84/86); the positive predictive value was 95.7% (95% CI 85.5-98.8) (44/46); and the negative predictive value, 98.8% (95% CI 93.6-99.8) (84/85). MTB/RIF detected 13/14 smear-negative TB cases, outperforming smear microscopy [97.8% (44/45) vs. 68.9% (31/45); p = 0.0002]. For rifampicin resistance detection, sensitivity of MTB/RIF was 100% (95% CI 61.0-100.0) (6/6); specificity was 91.0% (95% CI 76.4-96.9) (30/33); the positive predictive value was 66.7% (95% CI 35.4-87.9) (6/9); and the negative predictive value was 100% (95% CI 88.7 -100.0) (30/30). CONCLUSIONS/SIGNIFICANCE: In HIV patients in our population with a high clinical suspicion of TB, MTB/RIF performed well for TB diagnosis and outperformed smear microscopy.


 Gotuzzo EMarkowitz MRatanasuwan WSmith GPrada GMorales-Ramirez JO; Strohmaier KM; Lu CBhanja SNguyen BYTeppler H;

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Sustained Efficacy and Safety of Raltegravir After 5 Years of Combination Antiretroviral Therapy as Initial Treatment of HIV-1 Infection: Final Results of a Randomized, Controlled, Phase II Study (Protocol 004).

J Acquir Immune Defic Syndr. 2012 Sep 1;61(1):73-77.

ABSTRACT: Raltegravir as initial HIV therapy was examined in a double-blind study; 160 patients were randomized to raltegravir (400 mg bid after dose-ranging), 38 to efavirenz, both with tenofovir/lamivudine. At week 240, HIV-RNA remained <50 copies per milliliter in 68.8% (raltegravir) versus 63.2% (efavirenz), and CD4 increases were 302 versus 276 cells per microliter, respectively. Early HIV-RNA decline predicted later CD4 increases in both groups. Raltegravir resistance was observed in 3 of 10 raltegravir recipients with virologic failure. Few drug-related adverse events were reported after week 48. Raltegravir had minimal effect on laboratory values, including lipids. Raltegravir with tenofovir/lamivudine showed durable efficacy and good tolerability over 5 years.


Velasco JLAlonso JACalvo IArévalo J.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Vanishing neoclassical viscosity and physics of the shear layer in stellarators.

Phys Rev Lett. 2012 Sep27  28;109(13):135003.

ABSTRACT: The drift kinetic equation is solved for low density TJ-II plasmas employing slowly varying, time-dependent profiles. This allows us to simulate density ramp-up experiments and describe from first principles the formation and physics of the radial electric field shear layer. The main features of the transition are perfectly captured by the calculation, and good quantitative agreement is also found. The results presented here, that should be valid for other nonquasisymmetric stellarators, provide a fundamental explanation for a wealth of experimental observations connected to the shear layer emergence in TJ-II. The key quantity is the neoclassical viscosity, which is shown to go smoothly to zero when the critical density is approached from below. This makes it possible for turbulence-related phenomena, and particularly zonal flows, to arise in the neighborhood of the transition.


 Valero MAPeriago MVPérez-Crespo IAngles RVillegas FAguirre CStrauss WEspinoza JRHerrera PTerashima ATamayo HEngels DGabrielli AFMas-Coma S.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Field evaluation of a coproantigen detection test for fascioliasis diagnosis and surveillance in human hyperendemic areas of andean countries.

PLoS Negl Trop Dis. 2012 Sep13; 6(9):e1812. 

ABSTRACT: BACKGROUND: Emergence of human fascioliasis prompted a worldwide control initiative including a pilot study in a few countries. Two hyperendemic areas were chosen: Huacullani, Northern Altiplano, Bolivia, representing the Altiplanic transmission pattern with high prevalences and intensities; Cajamarca valley, Peru, representing the valley pattern with high prevalences but low intensities. Coprological sample collection, transport and study procedures were analyzed to improve individual diagnosis and subsequent treatments and surveillance activities. Therefore, a coproantigen-detection technique (MM3-COPRO ELISA) was evaluated, using classical techniques for egg detection for comparison.

METHODOLOGY AND FINDINGS: A total of 436 and 362 stool samples from schoolchildren of Huacullani and Cajamarca, respectively, were used. Positive samples from Huacullani were 24.77% using the MM3-COPRO technique, and 21.56% using Kato-Katz. Positive samples from Cajamarca were 11.05% using MM3-COPRO, and 5.24% using rapid sedimentation and Kato-Katz. In Huacullani, using Kato-Katz as gold standard, sensitivity and specificity were 94.68% and 98.48%, respectively, and using Kato-Katz and COPRO-ELISA test together, they were 95.68% and 100%. In Cajamarca, using rapid sedimentation and Kato-Katz together, results were 94.73% and 93.58%, and using rapid sedimentation, Kato-Katz and copro-ELISA together, they were 97.56% and 100%, respectively. There was no correlation between coproantigen detection by optical density (OD) and infection intensity by eggs per gram of feces (epg) in Cajamarca low burden cases (<400 epg), nor in Huacullani high burden cases (≥400 epg), although there was in Huacullani low burden cases (<400 epg). Six cases of egg emission appeared negative by MM3-COPRO, including one with a high egg count (1248 epg).

CONCLUSIONS: The coproantigen-detection test allows for high sensitivity and specificity, fast large mass screening capacity, detection in the chronic phase, early detection of treatment failure or reinfection in post-treated subjects, and usefulness in surveillance programs. However, this technique falls short when evaluating the fluke burden on its own.



Ricaldi JN; Fouts DE; Selengut JD; Harkins DM; Patra KP; Moreno A; Lehmann JS; Purushe J; Sanka R; Torres M; Webster NJ; Vinetz JM; Matthias MA.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Whole genome analysis of leptospia licerasiae provides insight into lleptospiral evolution and pathogenicity

PLoS Negl Trop Dis. 2012 Oct; 6(10):e1853.

Abstract: The whole genome analysis of two strains of the first intermediately pathogenic leptospiral species to be sequenced (Leptospira licerasiae strains VAR010 and MMD0835) provides insight into their pathogenic potential and deepens our understanding of leptospiral evolution. Comparative analysis of eight leptospiral genomes shows the existence of a core leptospiral genome comprising 1547 genes and 452 conserved genes restricted to infectious species (including L. licerasiae) that are likely to be pathogenicity-related. Comparisons of the functional content of the genomes suggests that L. licerasiae retains several proteins related to nitrogen, amino acid and carbohydrate metabolism which might help to explain why these Leptospira grow well in artificial media compared with pathogenic species. L. licerasiae strains VAR010(T) and MMD0835 possess two prophage elements. While one element is circular and shares homology with LE1 of L. biflexa, the second is cryptic and homologous to a previously identified but unnamed region in L. interrogans serovars Copenhageni and Lai. We also report a unique O-antigen locus in L. licerasiae comprised of a 6-gene cluster that is unexpectedly short compared with L. interrogans in which analogous regions may include >90 such genes. Sequence homology searches suggest that these genes were acquired by lateral gene transfer (LGT). Furthermore, seven putative genomic islands ranging in size from 5 to 36 kb are present also suggestive of antecedent LGT. How Leptospira become naturally competent remains to be determined, but considering the phylogenetic origins of the genes comprising the O-antigen cluster and other putative laterally transferred genes, L. licerasiae must be able to exchange genetic material with non-invasive environmental bacteria. The data presented here demonstrate that L. licerasiae is genetically more closely related to pathogenic than to saprophytic Leptospira and provide insight into the genomic bases for its infectiousness and its unique antigenic characteristics.



Mosquito SRuiz JPons MJDurand DBarletta FOchoa TJ.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Molecular mechanisms of antibiotic resistance in diarrhoeagenic Escherichia coli isolated from children.

Int J Antimicrob Agents. 2012 Oct 15. pii: S0924-8579(12)00334-2.

 ABSTRACT: Diarrhoeagenic Escherichia coli (DEC) are an important cause of diarrhoea in children and are associated with high antibiotic resistance. However, there are few studies on the molecular mechanisms of resistance in this group of bacteria. The aim of this study was to determine the mechanisms associated with antibiotic resistance in the most common phenotypes of DEC. A total of 369 E. coli strains [commensal strains and DEC from children with ('DEC-diarrhoea') or without ('DEC-control') diarrhoea] isolated from children aged <1 year in periurban districts of Lima, Peru, were analysed. In total, 154 ampicillin-resistant strains (36 commensals, 33 DEC-control and 85 DEC-diarrhoea) were studied by PCR for the most prevalent resistance mechanisms to ampicillin, trimethoprim/sulfamethoxazole (SXT), tetracycline and chloramphenicol as well as for integrase types 1 and 2. In addition, restriction fragment length polymorphism was performed for SXT-resistant strains. Commensal strains were more frequently resistant to nalidixic acid and ciprofloxacin (68% and 28%, respectively) than DEC strains (23% and 2%, respectively) (P<0.05). DEC-diarrhoea strains were more frequently SXT-resistant (78%) compared with DEC-control strains (65%) and commensal strains (60%) (P<0.05). The most frequent mechanisms of antibiotic resistance in DEC strains were: for β-lactams, bla(TEM) (31%; 37/118); for SXT, sul2 (48%; 49/103); for tetracycline, tetA (27%; 23/84); and for chloramphenicol, cat (80%; 28/35). The genes sul1 and dfrA1, related to SXT resistance, were more frequent in the DEC-diarrhoea group (41% and 28%, respectively) than in the other two groups (P<0.05). There was a high diversity of resistance genes in DEC, including symptomatic strains.



 Fraga JVeland NMontalvo AMPraet NBoggild AKValencia BMArévalo JLlanos-Cuentas ADujardin JCVan der Auwera G.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Accurate and rapid species typing from cutaneous and mucocutaneous leishmaniasis lesions of the New World.

Diagn Microbiol Infect Dis. 2012 Oct;74(2):142-50

ABSTRACT: The heat-shock protein 70 gene (hsp70) has been exploited for Leishmania species identification in the Old and New World, using polymerase chain reaction (PCR) followed by restriction fragment length polymorphism analysis. Three new Leishmania-specific hsp70 PCRs were recently described, and we applied 2 of these on 89 clinical samples from a total of 73 Peruvian patients with either cutaneous or mucocutaneous leishmaniasis. The new PCRs on average showed a 2- to 3-fold improved sensitivity in the tested sample types (lesion biopsies, aspirates, and scrapings), for both genus detection and species typing, and were most successful in biopsies. Leishmania braziliensis, L. peruviana, and L. guyanensis were encountered. About one third of the L. braziliensis parasites contained 2 hsp70 alleles. This study is a paradigm for the implementation of a globally applicable upgraded tool for the identification of Leishmania directly on human specimens from cutaneous and mucocutaneous lesions in the New World.



Sanchez N; Ugarte-Gil C; Solorzano N; Maguiña C; Pachas P; Blazes D; Bailey R;  Mabey D; Moore D.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Bartonella bacilliformis: A Systematic Review of the Literature to Guide the Research Agenda for Elimination.

PLoS Neglected Tropical Diseases: Research Article, published 25 Oct 2012 vol. 6(10) e1819

ABSTRACT: BACKGROUND: Carrion's disease affects small Andean communities in Peru, Colombia and Ecuador and is characterized by two distinct disease manifestations: an abrupt acute bacteraemic illness (Oroya fever) and an indolent cutaneous eruptive condition (verruga Peruana). Case fatality rates of untreated acute disease can exceed 80% during outbreaks. Despite being an ancient disease that has affected populations since pre-Inca times, research in this area has been limited and diagnostic and treatment guidelines are based on very low evidence reports. The apparently limited geographical distribution and ecology of Bartonella bacilliformis may present an opportunity for disease elimination if a clear understanding of the epidemiology and optimal case and outbreak management can be gained. Methods: All available databases were searched for English and Spanish language articles on Carrion's disease. In addition, experts in the field were consulted for recent un-published work and conference papers. The highest level evidence studies in the fields of diagnostics, treatment, vector control and epidemiology were critically reviewed and allocated a level of evidence, using the Oxford Centre for Evidence-Based Medicine (CEBM) guidelines. Results: A total of 44 studies were considered to be of sufficient quality to be included in the analysis. The majority of these were level 4 or 5 (low quality) evidence and based on small sample sizes. Few studies had been carried out in endemic areas. Conclusions : Current approaches to the diagnosis and management of Carrion's disease are based on small retrospective or observational studies and expert opinion. Few studies take a public health perspective or examine vector control and prevention. High quality studies performed in endemic areas are required to define optimal diagnostic and treatment strategies.



Lopez-Perez MVillasis EMachado RLPóvoa MMVinetz JMBlair SGamboa DLustigman S.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Plasmodium falciparum Field Isolates from South America Use an Atypical Red Blood Cell Invasion Pathway Associated with Invasion Ligand Polymorphisms.

PLoS One. 2012; 7(10): e4791

 ABSTRACT: Studies of Plasmodium falciparum invasion pathways in field isolates have been limited. Red blood cell (RBC) invasion is a complex process involving two invasion protein families; Erythrocyte Binding-Like (EBL) and the Reticulocyte Binding-Like (PfRh) proteins, which are polymorphic and not fully characterized in field isolates. To determine the various P. falciparum invasion pathways used by parasite isolates from South America, we studied the invasion phenotypes in three regions: Colombia, Peru and Brazil. Additionally, polymorphisms in three members of the EBL (EBA-181, EBA-175 and EBL-1) and five members of the PfRh (PfRh1, PfRh2a, PfRh2b, PfRh4, PfRh5) families were determined. We found that most P. falciparum field isolates from Colombia and Peru invade RBCs through an atypical invasion pathway phenotypically characterized as resistant to all enzyme treatments (NrTrCr). Moreover, the invasion pathways and the ligand polymorphisms differed substantially among the Colombian and Brazilian isolates while the Peruvian isolates represent an amalgam of those present in the Colombian and Brazilian field isolates. The NrTrCr invasion profile was associated with the presence of the PfRh2a pepC variant, the PfRh5 variant 1 and EBA-181 RVNKN variant. The ebl and Pfrh expression levels in a field isolate displaying the NrTrCr profile also pointed to PfRh2a, PfRh5 and EBA-181 as being possibly the major players in this invasion pathway. Notably, our studies demonstrate the uniqueness of the Peruvian P. falciparum field isolates in terms of their invasion profiles and ligand polymorphisms, and present a unique opportunity for studying the ability of P. falciparum parasites to expand their invasion repertoire after being reintroduced to human populations. The present study is directly relevant to asexual blood stage vaccine design focused on invasion pathway proteins, suggesting that regional invasion variants and global geographical variation are likely to preclude a simple one size fits all type of vaccine.



Villasis E;  Lopez-Perez M;  Torres KGamboa D;  Neyra V;  Bendezu J;  Tricoche NLobo CVinetz JMLustigman S.

Universidad Peruana Cayetano Heredia

Anti-Plasmodium falciparum invasion ligand antibodies in a low malaria transmission region, Loreto, Peru.

Malar J. 2012 Oct 30;11(1):361.

ABSTRACT: Erythrocyte invasion by Plasmodium falciparum is a complex process that involves two families; Erythrocyte Binding-Like (EBL) and the Reticulocyte Binding-Like (PfRh) proteins. Antibodies that inhibit merozoite attachment and invasion are believed to be important in mediating naturally acquired immunity and immunity generated by parasite blood stage vaccine candidates. The hypotheses tested in this study were 1) that antibody responses against specific P. falciparum invasion ligands (EBL and PfRh) differ between symptomatic and asymptomatic individuals living in the low-transmission region of the Peruvian Amazon and 2), such antibody responses might have an association, either direct or indirect, with clinical immunity observed in asymptomatically parasitaemic individuals. METHODS:  ELISA was used to assess antibody responses (IgG, IgG1 and IgG3) against recombinant P. falciparum invasion ligands of the EBL (EBA-175, EBA-181, EBA-140) and PfRh families (PfRh1, PfRh2a, PfRh2b, PfRh4 and PfRh5) in 45 individuals infected with P. falciparum from Peruvian Amazon. Individuals were classified as having symptomatic malaria (N=37) or asymptomatic infection (N=8). RESULTS:  Antibody responses against both EBL and PfRh family proteins were significantly higher in asymptomatic. compared to symptomatic individuals, demonstrating an association with clinical immunity. Significant differences in the total IgG responses were observed with EBA-175, EBA-181, PfRh2b, and MSP119 (as a control). IgG1 responses against EBA-181, PfRh2a and PfRh2b were significantly higher in the asymptomatic individuals. Total IgG antibody responses against PfRh1, PfRh2a, PfRh2b, PfRh5, EBA-175, EBA-181 and MSP119 proteins were negatively correlated with level of parasitaemia. IgG1 responses against EBA- 181, PfRh2a and PfRh2b and IgG3 response for PfRh2a were also negatively correlated with parasitaemia. CONCLUSIONS: These data suggest that falciparum malaria patients who develop clinical immunity (asymptomatic parasitaemia) in a low transmission setting such as the Peruvian Amazon have antibody responses to defined P. falciparum invasion ligand proteins higher than those found in symptomatic (non-immune) patients. While these findings will have to be confirmed by larger studies, these results are consistent with a potential role for one or more of these invasion ligands as a component of an anti-P. falciparum vaccine in low-transmission malaria-endemic regions.



Barletta FOchoa TJCleary TG

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Multiplex Real-Time PCR (MRT-PCR) for Diarrheagenic.

Methods Mol Biol. 2013;943:307-14

ABSTRACT: Diarrheagenic Escherichia coli strains are important causes of diarrhea in children from the developing world and are now being recognized as emerging enteropathogens in the developed world. Current methods of detection are too expensive and labor-intensive for routine detection of these organisms to be practical. We developed a real-time fluorescence-based multiplex PCR for the detection of all six of the currently recognized classes of diarrheagenic E. coli. The primers were designed to specifically amplify eight different virulence genes in the same reaction: aggR for enteroaggregative E. coli (EAEC), stIa/stIb and lt for enterotoxigenic E. coli (ETEC), eaeA for enteropathogenic E. coli (EPEC), stx1 and stx2 for Shiga toxin-producing E. coli (STEC), ipaH for enteroinvasive E. coli (EIEC), and daaD for diffusely adherent E. coli (DAEC).


Pantenburg BOchoa TJEcker LRuiz J.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Use of commercially available oral rehydration solutions in Lima, Peru.

Am J Trop Med Hyg. 2012 Jun;86(6):922-4.

ABSTRACT: Caregivers' practices concerning oral rehydration of young children during diarrheal illness were investigated in a periurban community of low socioeconomic level in Lima, Peru. Data of 330 caregivers of children aged 6-36 months were analyzed; 72.7% of all caregivers would give commercially available oral rehydration solutions (ORSs). However, only 58.6% of those caregivers with children that had experienced diarrhea during the previous week stated that they had used commercially available ORSs, a significantly lower percentage. The main reason for not using commercially available ORSs was that caregivers did not know about them. Of all recipes caregivers provided for homemade ORS, none contained the recommended concentrations of sugar and salt. Educating caregivers about availability, benefits, and use of commercially available ORSs as well as correct preparation of homemade ORS is urgently needed.



Ochoa TJChea-Woo EBaiocchi NPecho ICampos MPrada AValdiviezo GLluque ALai DCleary TG.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Randomized Double-Blind Controlled Trial of Bovine Lactoferrin for Prevention of Diarrhea in Children.

J Pediatr. 2012 Aug 30. [Epub ahead of print]

ABSTRACT: OBJECTIVE: To determine the effect of bovine lactoferrin (bLF) on prevention of diarrhea in children. STUDY DESIGN: We conducted a community-basedrandomized double-blind placebo controlled trial comparing supplementation with bLF vs placebo. Previously weaned children were enrolled at 12-18 months and followed for 6 months with daily home visits for data collection and supplement administration. Anthropometric measures were done monthly. RESULTS: Five hundred fifty-five childrenwere randomized: 277 to bLF and 278 to placebo; 65 dropped out; 147 894 doses were administered (92% compliance). Overall there were 91 446 child-days of observation and 1235 diarrhea episodes lasting 6219 days. The main pathogens isolated during diarrheal episodes were norovirus (35.0%), enteropathogenic E coli (11.4%), Campylobacter (10.6%), enteroaggregative E coli (8.4%), enterotoxigenic E coli (6.9%), and Shigella (6.6%). The diarrhea incidence was not different between groups: 5.4 vs 5.2 episodes/child/year for bLF and placebo, respectively (P = .375). However, the diarrhea longitudinal prevalence was lower in the bLF group vs placebo (6.6% vs 7.0%, P = .017), as well as the median duration of episodes (4.8 vs 5.3 days, P = .046), proportion of episodes with moderate or severe dehydration (1.0% vs 2.6%, P = .045), and liquid stools load (95.0 vs 98.6) liquid stools/child/year, P < .001). There were no adverse events related to the intervention.



García CRijnders MIBruggeman CSamalvides FStobberingh EEJacobs J.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Antimicrobial resistance and molecular typing of Staphylococcus aureus bloodstream isolates from hospitals in Peru.

J Infect. 2012 Nov;65(5):406-11.

ABSTRACT: OBJECTIVES: Methicillin-resistant Staphylococcus aureus (MRSA) infections are of worldwide concern. The present study describes the antimicrobial resistance and molecular typing of methicillin-resistant and methicillin-susceptible S. aureus (MSSA) bloodstream isolates in Peru. METHODS: Consecutive non-duplicate S. aureus bloodstream isolates were collected over a 15-month period (2008-2009) from seven hospitals in Lima and Callao, two contiguous cities in Peru. Detection of mecA gene, spa typing and Staphylococcal Chromosomal Cassette (SCC)mec typing were performed. Antimicrobial resistance was assessed by disk diffusion. RESULTS:Of 338 isolates, MRSA rate was 50.0%. Among MRSA isolates (n = 169), 81.7% were associated to MLST CC5, 68.8% had spa t149/SCCmec I, and more than 85% were co-resistant to ciprofloxacin, clindamycin, erythromycin and gentamicin; 8.9% (n = 15) were associated to MLST CC8, 14 of them had spa t148/SCCmec IV, and more than 70% were co-resistant to ciprofloxacin, clindamycin and erythromycin. Among MSSA isolates (n = 169), there was a higher diversity of spa types (n = 56) compared to MRSA isolates (n = 17), 27.2% were associated to MLST CC8, 23.7% were resistant to erythromycin and clindamycin resistance exceeded 20%. CONCLUSIONS: MRSA rate among bloodstream isolates in Peru was 50%, with MLST CC5/t149/SCCmec I representing the most frequent clone.



Gomes CPons MJMagallon-Tejada ADurand DLluque AMosquito SRiveros MMercado EPrada AOchoa TJRuiz J.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

In Vitro Development and Analysis of Escherichia coli and Shigella boydii Azithromycin-Resistant Mutants.

Microb Drug Resist. 2012 Nov 23. [Epub ahead of print]


Abstract: The aim of this study was to develop and analyze in vitro azithromycin (AZM)-resistant mutants of Escherichia coli and Shigella boydii. Three clinical isolates of E. coli and one S. boydii isolated from feces samples collected from children under 5 years of age with diarrhea in Lima, Peru were inoculated onto Mueller-Hinton plates containing increasing serial dilutions of AZM ranging from their specific minimal inhibitory concentration (2 or 4 mg/l) to 64 mg/l. From these plates, 16 AZM-resistant mutants were selected to determine the stability of the resistance and the presence of cross resistance with other antibiotics. The role of Phe-Arg-β-Naphthylamide (PAβN)-inhibitible efflux pumps as well as the presence of mutations in the rplV, rplD, and rrlH (23S rRNA) genes and alterations in the outer membrane profiles were determined in these 16 mutants. The rate of mutation ranged from < 2.70×10(-10) to 2.17×10(-7) for E. coli and from < 9.58×10(-10) to 1.05×10(-8) for S. boydii. E. coli mutants showed an increase in the AZM-MIC up to sixfold with one strain achieving a MIC >256 mg/l. In contrast, S. boydii only presented increases of up to twofold in MIC levels. All the strains obtained, but one showed stable AZM resistance. In the presence of PAβN, the AZM MICs decreased to parental levels in Shigella mutants, while no MIC returned to parental levels among the E. coli mutants. No cross resistance to other classes of antibiotics was found. These results show the relevance of PAβN-inhibitible efflux pumps in the basal levels and development of AZM resistance. Further studies to characterize the remaining unidentified mechanisms of AZM resistance are needed.



Valencia BMVeland NAlba MAdaui VArevalo JLow DELlanos-Cuentas ABoggild AK.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Non-invasive cytology brush PCR for the diagnosis and causative species identification of american cutaneous leishmaniasis in peru.

PLoS One. 2012;7(11):e49738

ABSTRACT: Traditional methods of detecting Leishmania from cutaneous lesions involve invasive diagnostic procedures, such as scrapings, which cause discomfort, require technical expertise, and carry risks of invasive procedures. We compared the performance of 2 novel, molecular-based non-invasive methods for the diagnosis of cutaneous leishmaniasis (CL). METHODS: Consecutive patients presenting to the Leishmania Clinic at the Hospital Nacional Cayetano Heredia were enrolled. PCR was performed on filter paper lesion impressions (FPLIs), cytology brushes, and lancets for detection of Leishmania DNA. Smears from lesion scrapings and leishmanin skin test were also performed. Outcome measures were sensitivity and specificity. Composite reference standard was any 2 of 5 tests positive. Species identification was performed by PCR assays of positive specimens. RESULTS: Ninety patients with 129 lesions were enrolled, 117 of which fulfilled reference criteria for a diagnosis of CL. Of these 117 lesions, 113 were positive by PCR of lancets used for lesion scrapings versus 116 by PCR of FPLIs (p = 0.930) or 116 by PCR of cytology brushes (p = 0.930). Sensitivity and specificity of PCR on lancets were 96.6% [95% CI 93.3-99.9%] and 100%, respectively. Sensitivity and specificity of FPLI PCR were 99.1% [95% CI 97.4-100%] and 100%, respectively. Sensitivity and specificity of cytology brush PCR were 99.1% [95% CI 97.4-100%] and 100%, respectively. Giemsa-stained lesion smear and leishmanin skin test had inferior sensitivities at 47.9% [95% CI 38.9-57.0%] and 82.3% [95% CI 73.9-90.7%], respectively, compared to PCR of invasive or non-invasive specimens (p<0.001). CONCLUSIONS: Cytology brush PCR constitutes a sensitive and specific alternative to traditional diagnostic assays performed on invasive specimens such as lesion scrapings. It performs comparatively to non-invasive FPLI PCR. This novel, rapid, and well-tolerated method has the potential for widespread use in the field and in pediatric populations where traditional specimen collection is difficult.



Ricaldi JN; Matthias MA; Vinetz JM; Lewis Amanda.

Universidad Peruana Cayetano Heredia. Instituto de Medicina Tropical “Alexander von Humboldt”

Expression of sialic acids and other nonulosonic acids in Leptospira.

BMC Microbiology 2012; (11):e49738

Abstract: BACKGROUND: Sialic acids are negatively charged nine carbon backbone sugars expressed on mammalian cell surfaces. Sialic acids are part of a larger family of nonulosonic acid (NulO) molecules that includes pseudaminic and legionaminic acids. Microbial expression of sialic acids and other nonulosonic acids has been shown to contribute to host-microbe interactions in a variety of contexts, including participation in colonization, immune subversion, and behaviors such as biofilm formation, autoagglutination and motility. Previous research has suggested that some spirochetes may also express these molecules. RESULTS: Here we use a combination of molecular tools to investigate the presence of NulO biosynthetic gene clusters among clinical and saprophytic isolates of the genus Leptospira. Polymerase chain reaction and Southern blotting suggested that a variety of leptospires encoded NulO biosynthetic pathways. High performance liquid chromatography and mass spectrometry analyses provided biochemical evidence that di-N-acetylated NulO molecules are expressed at relatively high levels by L. interrogans serovar Lai strain 55601, and at lower levels by L. alexanderi serovar Manhao and L. fainei serovar Hurstbridge. Endogenous expression of N-acetylneuraminic acid (Neu5Ac, the most common sialic acid) was documented in L. interrogans serovar Copenhageni strain L1-130. Neu5Ac biosynthesis is also supported by a unique gene fusion event resulting in an enzyme with an N-terminal N-acetylneuraminic acid synthase domain and a C-terminal phosphatase domain. This gene fusion suggests that L. interrogans uses a Neu5Ac biosynthetic pathway more similar to animals than to other bacteria. Analysis of the composition and phylogeny of putative NulO biosynthetic gene clusters in L. interrogans serovar Lai and serovar Copenhageni revealed that both strains have complete biosynthetic pathways for legionamimic acid synthesis, a molecule with the same stereochemistry as sialic acid. Lectin-based affinity purification of NulO-modified molecules, followed by mass spectrometric identification suggests post-translational modification of surface lipoproteins, including Loa22. CONCLUSIONS: Leptospira species encode NulO biosynthetic pathways and synthesize multiple NulO molecules including sialic acid. Additional studies are needed to clarify the exact context and functional significance of NulO expression. These findings have implications for immune evasion during systemic leptospirosis.