Reevaluation of a Suspected Cronobacter sakazakii Outbreak in Mexico.

In 2010, two infants became ill at a hospital in Mexico. Subsequently, a range of clinical, environmental, and powdered and rehydrated infant formula isolates were identified by using a combination of phenotyping and PCR probes. The strains were clustered according to pulsed-field gel electrophoresis. The causative agent was reported as Cronobacter sakazakii, with powdered infant formula (PIF) identified as the likely source of the infections. This new study further characterized the isolates from this outbreak by using multilocus sequence typing and whole genome sequencing of selected strains. Though four PIF isolates and one hospital environmental isolate were identified as C. sakazakii sequence type 297 by multilocus sequence typing, they were isolated 6 months prior to the outbreak. Genotypic analyses of patient isolates identified them as Enterobacter hormaechei and Enterobacter spp. The pulsed-field gel electrophoresis profile of the Enterobacter spp. isolates matched those of isolates from previously unopened tins of PIF. E. hormaechei was only isolated from the two infants and not PIF. The reevaluation of this outbreak highlights the need for accurate detection and identification assays, particularly during outbreak investigations in which incorrect identifications may mislead the investigation and attribution of the source. Though the species responsible for the symptoms could not be determined, this outbreak demonstrated the possible transmission of Enterobacter spp. from PIF to infants. These are possibly the first reported cases of Enterobacter spp. infection of infants from bacterial-contaminated PIF.

Potential Salmonella transmission from ornamental fountains.

Besides the usual food and drinking-water vehicles, there are other routes by which Salmonella can be transmitted, especially at outdoor locations. Public fountains containing Salmonella offer models of exposure routes beyond those usually considered in the context of recreational use. The authors studied the bacteriological quality of water sampled from five ornamental fountains in Guadalajara, Mexico during two periods of six and of 10 months. Coliform bacteria and Escherichia coli were detected in 75 percent and 49 percent of the samples, respectively, and various serovars of Salmonella enterica were found in 12.4 percent of samples. In addition to risks from ingestion of the contaminated waters; ornamental fountains may also pose risks to people in the vicinity from inhalation of mists.

Contaminación del ceviche de pescado por Salmonella en Guadalajara, Jalisco, México / Contamination of fish ceviche by Salmonella in Guadalajara, Jalisco, Mexico

El presente estudio se realizó para conocer la incidencia de contaminación por Salmonella del pescado preparado y puesto a la venta en 89 comercios fijos y ambulantes de la ciudad de Guadalajara, Jalisco, México. El pH de las muestras analizadas osciló entre 3,8 y 5,2 (mediana= 4,55), y su temperatura, entre 9 y 29 C. El 16 porciento de las 221 muestras estudiadas (porciones de 20 g) fueron positivas a Salmonella. Los porcentajes de positividad de las muestras vendidas en establecimientos fijos y ambulantes fueron, respectivamente, 12 y 20 porciento. Estos porcentajes fueron más elevados en las épocas templadas y calurosas que en las frías. Para aislar Salmonella, el uso de preenriquecimiento resultó ser menos eficiente que el enriquecimiento directo. En dos de las ocho muestras con pH menor de 4,0 se aislaron Salmonella. Los resultados indican que el consumo de ceviche supone un riesgo para la salud, especialmente en las personas cuya resistencia a los enteropatógenos transmitidos por alimentos es baja, y que, por tanto, debe hacerse hincapié en el escaso valor del jugo de limón como garante de la inocuidad del ceviche

Contaminación del ceviche de pescado por Salmonella en Guadalajara, Jalisco, México / Contamination of fish ceviche by Salmonella in Guadalajara, Jalisco, Mexico

El presente estudio se realizó para conocer la incidencia de contaminación por Salmonella del pescado preparado y puesto a la venta en 89 comercios fijos y ambulantes de la ciudad de Guadalajara, Jalisco, México. El pH de las muestras analizadas osciló entre 3,8 y 5,2 (mediana= 4,55), y su temperatura, entre 9 y 29 C. El 16 porciento de las 221 muestras estudiadas (porciones de 20 g) fueron positivas a Salmonella. Los porcentajes de positividad de las muestras vendidas en establecimientos fijos y ambulantes fueron, respectivamente, 12 y 20 porciento. Estos porcentajes fueron más elevados en las épocas templadas y calurosas que en las frías. Para aislar Salmonella, el uso de preenriquecimiento resultó ser menos eficiente que el enriquecimiento directo. En dos de las ocho muestras con pH menor de 4,0 se aislaron Salmonella. Los resultados indican que el consumo de ceviche supone un riesgo para la salud, especialmente en las personas cuya resistencia a los enteropatógenos transmitidos por alimentos es baja, y que, por tanto, debe hacerse hincapié en el escaso valor del jugo de limón como garante de la inocuidad del ceviche

Fate of Salmonella in Salpicon, a Mexican Cold Shredded Beef Salad.

The fate of Salmonella during the preparation and storage of salpicon, a cold shredded beef salad commonly consumed in Mexico, was evaluated. Salmonella contamination was introduced by a person shredding the cooked beef, who previously had handled raw pork containing several native serotypes of Salmonella at 9,000 salmonellae per g. The salad was prepared with 0, 2, or 4% vinegar and was held for 48 h (8 at 24-26°C and 40 at 5-7°C). The optimal concentration of vinegar for acceptable salad flavor was 4%. The initial number of salmonellae in salads prepared with 0 or 4% vinegar was 20/g. Salmonella populations increased to 5,000 after 48 h. Salmonella did not grow in salad containing 4% vinegar (pH 5.3); however, the organism was isolated at levels of 7 cells per g at 48 h of incubation. Fourteen different serovars of Salmonella were isolated from the salads. Critical control points in the preparation and storage of salpicon are shredding the beef, the concentration of vinegar, and rapid cooling of salad before serving.