Toxigenic V. cholerae, V. parahaemolyticus, and V. vulnificus in oysters from the Gulf of Mexico and sold in Mexico City.

Oysters can accumulate potentially pathogenic bacteria, such as Vibrio cholerae, V. parahaemolyticus, and V. vulnificus. The aim of this study was to detect the presence of these Vibrio species and their toxigenic variants in oysters from the Gulf of Mexico sold in Mexico City. Oyster samples were studied using traditional culture and molecular polymerase chain reaction analysis. V. cholerae was present in 30.4% of the samples and its toxigenic variant chxA+ in 26.1%. It was isolated only in deshelled oysters, mainly in the dry season. V. parahaemolyticus was present in 95.7% of the samples and the toxigenic variant was found in 17.4%. V. vulnificus was identified in 60.9% of the samples, 38% of which corresponded to the environmental genotype and 21.7% to the clinical genotype, mainly in the cold season. Consumption of the oysters analyzed poses health risks due to the presence of Vibrio species, especially in deshelled oysters.

[Comparison of techniques for coliform bacteria extraction from sediment of Xochimilco Lake, Mexico]. / Comparación de técnicas para la extracción de bacterias coliformes del sedimento del lago de Xochimilco, México.

The need to separate bacteria from sediment in order to appropriately count them has led to test the efficacy of different techniques. In this research, traditional techniques such as manual shaking, homogenization, ultrasonication, and surfactant are compared. Moreover, the possibility of using a set of enzymes (pancreatine) and an antibiotic (ampicillin) for sediment coliform extraction is proposed. Samples were obtained from Xochimilco Lake in Mexico City. The most probable number of coliform bacteria was determined after applying the appropriate separation procedure. Most of the techniques tested led to numbers similar to those of the control (manual shaking). Only with the use of ampicillin, a greater total coliform concentration was observed (Mann-Whitney, z = 2.09; p = 0.03). It is possible to propose the use of ampicillin as a technique for total coliform extraction; however, it is necessary to consider sensitivity of bacteria to the antibiotic.

Comparación de técnicas para la extracción de bacterias coliformes del sedimento del lago de Xochimilco, México / [Comparison of techniques for coliform bacteria extraction from sediment of Xochimilco Lake, Mexico].

The need to separate bacteria from sediment in order to appropriately count them has led to test the efficacy of different techniques. In this research, traditional techniques such as manual shaking, homogenization, ultrasonication, and surfactant are compared. Moreover, the possibility of using a set of enzymes (pancreatine) and an antibiotic (ampicillin) for sediment coliform extraction is proposed. Samples were obtained from Xochimilco Lake in Mexico City. The most probable number of coliform bacteria was determined after applying the appropriate separation procedure. Most of the techniques tested led to numbers similar to those of the control (manual shaking). Only with the use of ampicillin, a greater total coliform concentration was observed (Mann-Whitney, z = 2.09; p = 0.03). It is possible to propose the use of ampicillin as a technique for total coliform extraction; however, it is necessary to consider sensitivity of bacteria to the antibiotic.

Comparación de técnicas para la extracción de bacterias coliformes del sedimento del lago de Xochimilco, México. / [Comparison of techniques for coliform bacteria extraction from sediment of Xochimilco Lake, Mexico].

The need to separate bacteria from sediment in order to appropriately count them has led to test the efficacy of different techniques. In this research, traditional techniques such as manual shaking, homogenization, ultrasonication, and surfactant are compared. Moreover, the possibility of using a set of enzymes (pancreatine) and an antibiotic (ampicillin) for sediment coliform extraction is proposed. Samples were obtained from Xochimilco Lake in Mexico City. The most probable number of coliform bacteria was determined after applying the appropriate separation procedure. Most of the techniques tested led to numbers similar to those of the control (manual shaking). Only with the use of ampicillin, a greater total coliform concentration was observed (Mann-Whitney, z = 2.09; p = 0.03). It is possible to propose the use of ampicillin as a technique for total coliform extraction; however, it is necessary to consider sensitivity of bacteria to the antibiotic.