Identification of bapA in Strains of Salmonella enterica subsp. enterica Isolated from Wild Animals Kept in Captivity in Sinaloa, Mexico.

bapA, previously named stm2689, encodes the BapA protein, which, along with cellulose and fimbriae, constitutes biofilms. Biofilms are communities of microorganisms that grow in a matrix of exopolysaccharides and may adhere to living tissues or inert surfaces. Biofilm formation is associated with the ability to persist in different environments, which contributes to the pathogenicity of several species. We analyzed the presence of bapA in 83 strains belonging to 17 serovars of Salmonella enterica subsp. enterica from wildlife in captivity at Culiacan's Zoo and Mazatlán's Aquarium. Each isolate amplified a product of 667 bp, which corresponds to the expected size of the bapA initiator, with no observed variation between different serovars analyzed. bapA gene was found to be highly conserved in Salmonella and can be targeted for the genus-specific detection of this organism from different sources. Since bapA expression improves bacterial proliferation outside of the host and facilitates resistance to disinfectants and desiccation, the survival of Salmonella in natural habitats may be favored. Thus, the risk of bacterial contamination from these animals is increased.

Salmonella serovars and antimicrobial resistance in strains isolated from wild animals in captivity in Sinaloa, Mexico.

The aim of the present study was to evaluate the frequency of antibiotic resistance in Salmonella spp. strains from wild animals in captivity at the Culiacan Zoo and the Mazatlan Aquarium in Sinaloa, Mexico. We identified 17 different Salmonella enterica serovars at a prevalence of 19.90% (Culiacan Zoo) and 6.25% (Mazatlan Aquarium). Antibiotic sensitivity tests revealed that, of the 83 strains studied, 100% were multidrug resistant (MDR). The drugs against which the greatest resistance was observed were: penicillin, erythromycin, dicloxacillin, ampicillin, cephalothin, and chloramphenicol. We therefore conclude that MDR is common among Salmonella isolates originating from wild animals in captivity in Sinaloa.

[Outbreak caused by Escherichia coli in Chalco, Mexico]. / Brote causado por Escherichia coli en Chalco, México.

OBJECTIVE: To identify the etiologic agent responsible for a disease outbreak following an overflow of sewage water in Valle de Chalco, Mexico. MATERIAL AND METHODS: A retrospective cross-sectional study was carried out. Rectal samples were collected from the population of Chalco valley, who suffered from diarrhea and vomiting during a natural disaster that took place on May 31, 2000. The Instituto de Diagnóstico y Referencia Epidemiológicos (Epidemic Reference and Diagnosis Institute, InDRE, Ministry of Health), received 1521 rectal swab samples from diarrhea cases, to test for E. coli strains. Statistical analysis was performed to find a difference of proportions between cases and non-cases (chi-squared test). ETEC, EIEC, EPEC and EHEC pathogenic E. coli groups were hybridized by colony blot. RESULTS: Strains isolated were ETEC (62.2%), EIEC (0.84%), EPEC (0.84%), and EHEC non-O157:H7 (0.08%); there was no hybridization in 36.02% of E. coli strains. Other isolated microorganisms were Salmonella spp (0.45%) and Shigella spp (0.06%). CONCLUSIONS: Enterotoxigenic E. coli was the most likely etiologic agent. Sanitary control strategies should be targeted to preventing outbreaks caused by this pathogenic agent. The English version of this paper is available at: http://www.insp.mx/salud/index.html.

Serotipos de Salmonella identificados en los servicios de salud de México / Salmonella serotypes isolated in Mexico's health services

Objetivo. Dar a conocer las variaciones de los serotipos de cepas de Salmonella aislados en diversos laboratorios públicos y privados de la República mexicana, así como en el del Instituto de Diagnóstico y Referencia Epidemiológicos (InDRE). Material y métodos. Se analizaron los serotipos de 24 394 cepas de Salmonella aisladas de diversas fuentes por los laboratorios de salud pública y privados de México, entre 1972 y 1999, 15 843 (64.9 por ciento) de origen humano y 8 551(35.1 por ciento) de origen no humano siguiendo el esquema de Kauffmann-White y utilizando antisueros producidos en el InDRE, de acuerdo con los lineamientos del Centro de Control y Prevención de Enfermedades, Atlanta (GA), de los Estados Unidos de América. Resultados. Se identificaron 199 serotipos, el más frecuente en muestras clínicas fue S. Typhimurium (20.4 por ciento) y, en segundo lugar, S. Enteritidis (18.3 por ciento). En este trabajo se muestra como S. Enteritidis tuvo un aumento gradual y desplazó a S. Typhimurium en los aislamientos desde 1991, y a la fecha es el serotipo que más se aísla. En cambio, en muestras no humanas el serotipo aislado con mayor frecuencia fue S. Derby (13.8 por ciento), seguido por S. Anatum (8.5 por ciento). Conclusiones. Los serotipos más frecuentes en México, tanto en muestras humanas como no humanas son: S. Typhimurium, S. Enteritidis, S. Derby, S. Agona y S. Anatum. Desde el punto de vista epidemiológico es necesario conocer cuáles son los serotipos circulantes y los de nueva introducción para poder determinar las acciones de prevención requeridas para los casos.