Thomas Weitzel

Field Evaluation of a Rota- and Adenovirus Immunochromatographic Assay Using Stool Samples from Children with Acute Diarrhea in Ghana

ABSTRACT We evaluated the Rida Quick rotavirus/adenovirus Combi rapid immunochromatographic test (ICT) under field conditions with Ghanaian children with acute diarrhea. Compared to PCR results, sensitivities and specificities were 75% and 95% for rotavirus and 22% and 84% for adenovirus. In resource-poor settings, ICTs may help to overcome difficulties in the diagnosis of rotavirus infection.

Mannose-Binding Lectin and Toll-Like Receptor Polymorphisms and Chagas Disease in Chile

Mannose-binding lectin (MBL) and Toll-like receptor (TLR) polymorphisms may influence susceptibility and manifestation of Trypanosoma cruzi infection. In northern Chile, we examined 61 asymptomatic patients with chronic Chagas disease (CD), 64 patients with chronic Chagas cardiomyopathy (CCC), and 45 healthy individuals. Low-producer MBL2*B genotypes were more common in CD patients (48%) than healthy individuals (31%; adjusted odds ratio = 2.3, 95% confidence interval = 1.01-5.4, P = 0.047) but did not differ with manifestation. In contrast, the heterozygous Toll-like receptor 4 (TLR4)-deficiency genotype D299G/T399I occurred more frequently in asymptomatic (14.8%) than CCC patients (3.1%; P = 0.02). TLR1-I602S, TLR2-R753Q, TLR6-S249P, and MAL/TIRAP-S180L did not associate with CD or CCC. These findings support the complement system to be involved in defense against Trypanosoma cruzi infection and indicate that curbed TLR4 activation might be beneficial in preventing CCC.

Prevalence and Risk Factors for Echinococcal Infection in a Rural Area of Northern Chile: A Household-Based Cross-Sectional Study

Background Hydatidosis is a zoonotic disease of worldwide distribution caused by Echinococcus granulosus. Our study aimed to determine the prevalence of human and canine echinococcosis as well as the associated risk factors in a rural area of the Limarí province in northern Chile. Methodology/Principal Findings A cross-sectional study was conducted between August and November 2009 using a stratified sampling design in each of the five districts of the province. In the selected villages, up to 10 households were sampled. Serum and fecal samples from an adult family member and a dog were collected from each participating household. Risk factors were assessed by standardized questionnaires. Seroprevalence was assessed using a multi-step approach: an ELISA for screening, IFA, IHA and western blot for confirmation of results, respectively. The prevalence of echinococcal infection in dogs was determined by coproantigen genus specific ELISA. Chi-square, Fisher tests and logistic regressions were used to assess risk factors for human seropositivity and dog copropositivity. A seroprevalence of 2.6% (10/403) and coproprevalence of 28% (26/93) was recorded for humans and dogs respectively. Contact with dogs and dog feces were risk factors for human seropositivity while dog copropositivity was associated with home slaughter of livestock (OR = 3.35; CI 90%: 1.16–6.85) and households de-worming dogs (OR = 2.82; CI 90%: 1.33–8.43). Conclusions/Significance Echinococcal infection of humans and their dogs is common in Limarí province. Risk factors for human seropositivity were related to contact with domestic dogs and their feces, whereas those for dogs were home slaughter of livestock and the practice of de-worming dogs.

Identification of Trueperella (Arcanobacterium) bernardiae by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis and by species-specific PCR.

Trueperella (Arcanobacterium) bernardiae was first described as a probable opportunistic pathogen in 1987. It was among isolates from a variety of clinical specimens in the Centers for Disease Control and Prevention described as group 2 coryneform bacteria (Na’Was et al., 1987). It was finally classified in the genus Arcanobacterium by Ramos et al. (1997). However, Yassin et al. (2011) proposed that Arcanobacterium bernardiae together with Arcanobacterium abortisuis, Arcanobacterium pyogenes, Arcanobacterium bialowiezense and Arcanobacterium bonasi should be reclassified into the newly described genus Trueperella. T. bernardiae has been reported as causative agent of urinary tract infections (Ieven et al., 1996; Lepargneur et al., 1998), from a patient suffering from septic arthritis (Adderson et al., 1998), from necrotizing fasciitis (Clarke et al., 2010), from coinfection with Staphylococcus aureus from chronic osteitis (Bemer et al., 2009) and more recently from bacteraemia of a patient with a deep soft tissue infection (Weitzel et al., 2011). However, the latter could be identified by partial sequencing of the 16S rRNA gene but not by classical biochemical tests, indicating that additional species characteristics would assist a future identification of this bacterial species.

An. gambiae gSG6-P1 evaluation as a proxy for human-vector contact in the Americas: a pilot study

BackgroundDuring blood meal, the female mosquito injects saliva able to elicit an immune response in the vertebrate. This immune response has been proven to reflect the intensity of exposure to mosquito bites and risk of infection for vector transmitted pathogens such as malaria. The peptide gSG6-P1 of An. gambiae saliva has been demonstrated to be antigenic and highly specific to Anopheles as a genus. However, the applicability of gSG6-P1 to measure exposure to different Anopheles species endemic in the Americas has yet to be evaluated. The purpose of this pilot study was to test whether human participants living in American countries present antibodies able to recognize the gSG6-P1, and whether these antibodies are useful as a proxy for mosquito bite exposure and malaria risk.MethodsWe tested human serum samples from Colombia, Chile, and the United States for the presence of IgG antibodies against gSG6-P1 by ELISA. Antibody concentrations were expressed as delta optical density (ΔOD) of each sera tested in duplicates. The difference in the antibody concentrations between groups was tested using the nonparametric Mann Whitney test (independent groups) and the nonparametric Wilcoxon matched-pairs signed rank test (dependent groups). All differences were considered significant with a P < 0.05.ResultsWe found that the concentration of gSG6-P1 antibodies was significantly correlated with malaria infection status and mosquito bite exposure history. People with clinical malaria presented significantly higher concentrations of IgG anti-gSG6-P1 antibodies than healthy controls. Additionally, a significant raise in antibody concentrations was observed in subjects returning from malaria endemic areas.ConclusionOur data shows that gSG6-P1 is a suitable candidate for the evaluation of exposure to Anopheles mosquito bites, risk of malaria transmission, and effectiveness of protection measures against mosquito bites in the Americas.

Catheter-associated bloodstream infection caused by Leifsonia aquatica in a haemodialysis patient: a case report.

Leifsonia aquatica is an aquatic coryneform rod that is capable of forming biofilms in environmental water sources. It has rarely been associated with human infections and its pathogenicity and clinical significance are uncertain. We describe a case of catheter-related bloodstream infection in a haemodialysis patient. The isolate grew on conventional media as a yellow-pigmented colony, but identification required molecular methods. Although the strain displayed reduced sensitivity to vancomycin, the clinical outcome was favourable after catheter removal and intravenous treatment with this antibiotic. Our report gives further evidence of the capability of this aquatic bacterium to cause human infection.

Zika Virus Infection Presenting with Postauricular Lymphadenopathy

A 28-year-old, otherwise healthy Chilean man presented in December 2015 with fever, headache, and myalgia. He had returned, 2 days ago, from a tourist trip to Colombia, where he had visited Bogota and the northern region including Cartagena de Indias, Santa Marta, and Tayrona National Park. During his return, he suffered nonspecific symptoms including sore throat, anorexia, and myalgia. A day later, he noted high grade fever and tender nodules behind his ears (Figure 1 ). Physical examination revealed fever (39.0°C), a maculopapular rash of the trunk and extremities (Figure 2 ), mild conjunctivitis, and a generalized lymphadenopathy with palpable tender axillary, cervical, and bilateral postauricular lymph nodes. After dengue and chikungunya virus infections were excluded by molecular methods, antigen detection, and IgM antibody testing, samples were sent to the national reference laboratory (Instituto de Salud Publica de Chile, Santiago, Chile), where Zika virus (ZIKV) nucleic acids were detected by real-time reverse transcription polymerase chain reaction (RT-PCR) as previously described.1 The sample was also positive using a commercial RT-PCR assay for the detection of ZIKV (Zika Virus genesig® Advanced Kit; Primerdesign™ Ltd., Southampton, United Kingdom) in the clinical laboratory, Clinica Alemana, Santiago. The patient recovered rapidly and without complications. Figure 1. Bilateral tender postauricular lymphadenopathy in patient with Zika virus infection. Figure 2. Maculopapular rash on the patients arm. Since 2015, ZIKV is rapidly emerging within the Americas, where it is disseminated by mosquitos of the Aedes genus. However, the virus is also transmitted by blood transfusion and, as recently suggested, by contact with infectious semen.2,3 Because of its possible association with fetal malformations and neurological complications, this epidemic has been declared a global public health emergency by the World Health Organization. The clinical presentation of the infection is similar to dengue including fever, rash, joint pain, conjunctivitis, myalgia, headache, and vomiting.4–6 Although lymphadenopathy has recently been described in patients with ZIKV infection in Brazil,7,8 it is usually not listed as a typical manifestation. Our case confirms that ZIKV might cause systemic lymphadenopathy including the posterior auricular lymph nodes. Because tender bilateral postauricular lymphadenopathy is a known clinical sign of postnatal rubella, it might mislead ZIKV diagnosis especially in pediatric patients.

Brotes de salmonelosis y el tamaño y rol del Estado en Chile

Resumen Durante el ano 2011 dos brotes de infecciones por Salmonella afectaron la Region Metropolitana (RM) de Chile: uno de fi ebre tifoidea y otro de gastroenteritis por Salmonella serotipo Enteritidis, infecciones que habian declinado en los ultimos anos. Se analizan las probables causas de esta reemergencia. Para el desarrollo de este trabajo se consultaron sitios web gubernamentales y de las Naciones Unidas. Las tasas de fi ebre tifoidea han declinado progresivamente hasta tasas muy bajas siendo la actual cercana a un caso por 100.000 habitantes, disminucion asociada a las mejorias en las condiciones de vida de la poblacion que se expresa por el indice de desarrollo humano alcanzado. El brote del ano 2011 estuvo asociado a un clon predominante que afecto al sector occidente de la RM y donde el unico factor de riesgo involucrado fue el consumo de verduras adquiridas en distintas ferias libres del mismo sector, sin lograr la identifi cacion del sitio de origen. Aunque la notifi cacion de esta enfermedad se ha optimizado en los ultimos anos, al igual que la capacidad de tipifi cacion molecular por parte del Laboratorio de Referencia (ISP), este brote se produce en forma coincidente con un bajo numero de fi scalizaciones alimentarias en la RM (la mas baja de Chile), explicado probablemente por el bajo numero de personal en la reparticion responsable en relacion al tamano de la poblacion. En el caso de las infecciones porUNLABELLED During year 2011 two outbreaks of Salmonella infection captured media attention in the Metropolitan Area (MA) in Chile: one of typhoid fever associated to Salmonella serotype Typhi, and the other, of gastroenteritis related to Salmonella serotype Enteritidis, both with decreasing or stable rates in the previous years. The aim of this work is to analyze probable causes of their reemergence. METHODS Several government websites were searched looking for epidemiological data. RESULTS Typhoid fever rates have declined to current values of 1 case per 100.000 habitants, a decreased associated to improvements in the human development index. The typhoid outbreak was associated to a predominant clone within the MA. The only risk factor identified was consumption of raw vegetables acquired in open fairs, but without identifying a common source. Despite improvements in disease notification and molecular epidemiology capabilities, this outbreak is coincidental with a reduced number of food inspection visits in the MA, probably explained by the limited personnel available for this task. In the case of Salmonella Enteritidis, rates have increased twice since 1998 (5.3 to 10.7 per 100.000 habitants) with an important increase in the number of outbreaks linked to this agent (7 to 31 annual outbreaks) since year 2005. Persistence of this problem is probably associated to the low surveillance of poultry farms made by the Chilean state, to the absence of a cold chain during collection, distribution and selling of eggs, and to the lack of an educational program directed to the population. The recent regulation that bans home-made mayonnaise in restaurant or fast food stores is an important advance that requires further evaluation. CONCLUSIONS The persistence and reemergence of different kind of Salmonellosis in Chile suggests chronic problems on the size and role of the Chilean state regarding food safety.

Head-to-head comparison of Microflex LT and Vitek MS systems for routine identification of microorganisms by MALDI-TOF mass spectrometry in Chile

Background Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is a new and revolutionary identification method for microorganisms and has recently been introduced into clinical microbiology in many industrialized countries in Europe and North America. Objectives Our study aimed to compare the performance and practicality of two commercial MALDI-TOF MS platforms in a head-to head manner at a routine laboratory in Chile. Methods During a five-month period in 2012–13, the diagnostic efficiency (correct identification rate) and agreement between Microflex LT (Bruker Daltonics) and Vitek MS (bioMérieux) was compared in a parallel manner to conventional identification including genotypic analysis for difficult-to-identify strains. The study included 804 microbial isolates: 252 Enterobacteriaceae, 126 non-fermenters, 36 other gram-negative rods, 279 gram-positive cocci, 32 gram-positive rods, 32 anaerobes, and 47 yeasts. Other relevant factors of the two devices such as user friendliness and connectivity were also evaluated and compared. Results Both systems correctly identified the vast majority (98%) of the isolates to the genus level. Vitek MS reached higher rates of identification to species and species complex level than Microflex LT (81% vs. 85% and 87% vs. 93%, respectively), which was mainly based on the higher performance among coagulase negative staphylococci and Candida isolates. The evaluation of user friendliness and other technical aspects showed only marginal differences, which slightly favored Vitek MS, mainly due to its ready-to-use supplies, easier connectivity and workflow integration, and availability of local technical support. Conclusions Both MALDI-TOF MS systems permitted fast and accurate identification of most microbial strains and showed a high level of user-friendliness. The observed differences were marginal and slightly favored Vitek MS, mainly due to practicality and connectivity issues within our setting.

Hepatitis B prevalence and influence on HIV treatment outcome and mortality in the Chilean AIDS Cohort

OBJECTIVES To analyze the prevalence of hepatitis B virus (HBV) co-infection and its influence on mortality and treatment outcome within a large AIDS cohort in Chile. METHODS Clinical and epidemiological data from the Chilean AIDS Cohort were retrospectively analyzed. Adult patients tested for hepatitis B surface antigen (HBsAg) during the time period of October 2001 to October 2007 were included. RESULTS Of 5115 cohort patients, 1907 met the inclusion criteria. The prevalence of HBV co-infection was 8.4%. Overall mortality rates were 2.15 and 1.77 per 100 person-years for HBsAg-positive and HBsAg-negative HIV patients, respectively, with a mortality rate ratio of 1.22 (95% confidence interval 0.58-2.54). Kaplan-Meier survival and Cox regression analysis did not show significant differences between the groups. Virological and immunological responses to antiretroviral therapy (ART) were not influenced by HBsAg status, but in co-infected patients, initial ART was more frequently changed. CONCLUSIONS The prevalence of hepatitis B co-infection was 8.4%, indicating a markedly elevated hepatitis B risk compared to the general population in Chile. Neither treatment outcome nor overall mortality was influenced by hepatitis B co-infection. Still, patients with hepatitis B co-infection had less stable ART regimens, which might be related to a higher risk of hepatotoxic drug effects.