Oysters and estuarine water samples were collected monthly, from June 1998 to March 1999, in the Cananéia estuary, on the south coast of São Paulo, Brazil, and analyzed for bacterial hazards with and without depuration in filtered estuarine water. Aeromonas spp., Plesiomonas shigelloides, Vibrio cholerae O1, Vibrio parahaemolyticus, and Vibrio vulnificus were counted in oyster samples using the most probable number (MPN) and their presence verified in the surrounding estuarine water samples. The presence of Salmonella, Shigella, Escherichia coli O157:H7, and fecal coliforms counts were determined in oysters and in water samples too. Sixty percent of water samples contained fecal coliforms ranging from <1 to >200 CFU/100 ml and 100%, 30%, 20% and 10% were positive for V. parahaemolyticus, Salmonella, Aeromonas, and V. vulnificus in 5 l of water samples, respectively. In oyster samples, the fecal coliforms concentration ranged from <3.0 to > or =2.4 x 10(3) MPN/g in 40% of untreated and from <3.0 to 1.1 x 10(3) MPN/g in 40% of treated samples. Vibrio parahaemolyticus Kanagawa-negative was detected in all oyster samples and their concentration varied from 3.6 to > or =2.4 x 10(3) MPN/g. For the untreated oyster samples 80%, 70%, and 10% were positive for V. vulnificus (<3 - 11.0 MPN/g), Aeromonas (<3-15 MPN/g), and Salmonella (presence in 25 g), respectively. However, for treated oyster samples 60%, 30%, and 0% of them contained the same bacteria, respectively. Escherichia coli O157:H7, Shigella spp., P. shigelloides, and V. cholerae O1 were not detected in any of the samples. Fecal indicators did not correlate with Vibrio presence (p>0.05), although the isolation of Aeromonas species had a positive correlation (p = 0.017). The results showed no correlation between temperature, salinity, and bacteria (p > 0.05). The comparison between bacterial concentration in treated and untreated oyster samples, showed that only Aeromonas was higher in untreated oyster samples (p = 0.039). This study contributes toward creating a more global understanding of food-borne bacterial pathogens. The presence and concentration of viable bacterial hazards in oysters and water surrounding areas was determined for the first time on the south coast of São Paulo and it helps to define better the true microbial hazard in the aquatic environment and oysters.

Aeromonas has been described as an emergent foodborne pathogen of increasing importance. In this study, we report that 48% of 50 Pintado fish samples collected at the retail market of São Paulo city were positive for Aeromonas sp, as detected by the direct plating method. When the presence/absence method was used, the positivity was 42%. A. caviae was the most frequent species, followed by A. hydrophila and A. sobria. Production of cytotoxic enterotoxin, observed in suckling mouse assay, was detected in 67% of A. sobria strains, in 60% of A. hydrophila strains and in 40% of A. caviae strains. In vitro tests, performed with HEp-2 cells, showed that 88% of A. hydrophila, 27% of A. sobria and 13% of A. caviae strains were positive for this toxin. The in vivo production of cytotonic enterotoxin, tested after heating the filtrates at 56ºC for 20 minutes, was detected in 17% of A. sobria, in 10% of A. caviae and in none of A. hydrophila strains in vivo. All analyzed strains did not alter HEp-2 cells. 20% and 16% of A. sobria and A. caviae isolates, respectively, presented capacity to adhere to HEp-2 cells. In counterpart, invasion of HEp-2 cells was not observed in any isolate. The Aeromonas isolates were sensitive to the majority of the antimicrobiol agents tested.
Bactérias do gênero Aeromonas têm sido descritas como patógenos emergentes de importância crescente em alimentos. Neste estudo, relatamos que 48% das amostras de peixe "Pintado" coletado no comércio de São Paulo, foram positivas para Aeromonas sp quando isoladas pelo método de plaqueamento direto. Quando o método Presença/Ausência foi utilizado, a porcentagem de positividade foi de 42%. A. caviae foi a espécie mais freqüente, seguida por A. hydrophila e A. sobria. Produção de enterotoxina citotóxica, determinada em camundongos recém-nascidos, foi observada em 67% das cepas de A. sobria, em 60% das de A. hydrophila e em 40% das de A. caviae. No teste in vitro em células HEp- 88% das cepas de A. hydrophila, 27% das cepas de A. sobria e 13% das cepas de A. caviae revelaram-se positivas. Com relação a produção de enterotoxina citotônica, testada após o aquecimento do sobrenadante a 56ºC por 20 minutos, 17% das cepas de A. sobria, 10% das de A. caviae e nenhuma das de A. hydrophila foram positivas in vivo e para todas as cepas analisadas, os testes foram negativos em cultura de célula HEp-2. Quanto a capacidade de adesão, 20% das 5 cepas de A. sobria e 16% das 20 cepas de A. caviae aderiram a células HEp-2. A capacidade de invasão em células HEp-2 não foi detectada em nenhuma das cepas testadas. As cepas isoladas foram sensíveis a maior parte dos antimicrobianos testados

INTRODUÇÃOComo a água é um elemento imprescindível à vida animal, é necessário que se adotem medidas para garantir, tanto quanto possível, suas características, a fim de que seja própria ao consumo.É sabido que as necessidades dos animais, relativamente ao consumo de água, variam com a espécie, tipo de criação, alojamento, condições do ambiente, natureza da dieta e temperatura (Templeton

Beef tissues were contaminated with wet and dry manure. The manure was previously inoculated with Escherichia coli O157:H7 GFP, genetically modified with a plasmid encoding a protein that fluoresces green when exposed to long-wave ultraviolet light. After incubation at 37 degrees C for 5 days, the wet manure was spread on the surface of beef tissues at an average E. coli O157:H7 GFP level of 6.62 log CFU/cm2. Dry manure was obtained by subjecting wet manure to natural drying (simulating dry manure adhering to the hides of cattle) and was also applied to the surfaces of beef tissues. The degree of removal of E. coli O157:H7 GFP by washing was compared to the removal of cells of the same strain that had been inoculated as a suspension. The E. coli O157:H7 mixed into feces of cattle adhered more strongly to meat surfaces than that applied as a suspension, complicating the removal by conventional washing procedures. The fate of the bacterium mixed into wet or dry manure was evaluated. An initial decrease of the inoculated population was observed; this was probably an effect of the changed environment represented by the manure. After adaptation, the inoculated bacteria grew in the wet manure; a maximum population was reached in 5 days at 37 degrees C; levels declined with drying. The use of the GFP marker was of great value, since it allowed enumeration of E. coli O157:H7 in the presence of the natural flora of manure.