Occurrence of Salmonella spp in estuarine and coastal waters of Portugal

The presence of Salmonella and its relationship with indicator organisms of fecal pollution, such as total coliforms, fecal coliforms and fecal strept ococci, was studied at two marine zones in Portugal. Seventeen different Sa lmonella serotypes were isolated and identified, S. virchow was the most fr equently isolated (21.6%). In addition, a high percentage (35.1%) was recor ded for some Salmonella serotypes of clinical significance, namely S. enter itidis, S. infantis, S. typhimurium and S. virchow. In any of the samples f rom the two zones Salmonella was not detected in the absence of any of the indicator organisms. However, the incidence of Salmonella as a function of indicator concentration intervals established by the EEC standards was 0, 1 0 and 19.3% at guide values of total coliforms, fecal coliforms and fecal s treptococci, respectively in the Faro samples (south of Portugal). In contr ast, Salmonella incidence rates of 37.5, 36.4 and 33.3% were recorded at th e corresponding guide values the Caminha samples (north of Portugal). No si gnificant correlations (p > 0.005) were obtained between Salmonella and the indicators at the sampling stations; however, total coliforms and fecal st reptococci were the indicators most closely related to Salmonella in Caminh a and Faro samples, respectively. Survival experiments in Escherichia coli, Enterococcus faecalis and S. typhimurium, using diffusion chambers, were p erformed to verify whether the lack of correlation between indicators and S almonella was due to different inactivation rates in seawater. The results indicate that survival percentages of the three microorganisms tested were similar after 48 h of exposure to seawater.