Relationship between indicators of faecal pollution and presence of pathogenic microorganisms in coastal seawater.

This study evaluated the relationship between the traditional indicators of faecal pollution, Total Coliforms (TC), Faecal Coliforms (FC) and Faecal Streptococci (FS), and the presence of Salmonellae in coastal seawater in addition, the sensitivity of coliforms and streptococci tests was calculated. Finally, the detection of Staphylococcus aureus was evaluated as a possible additional parameter of coastal seawater quality. The 308 samples tested were drawn from the coastal seawaters along the Lecce-Brindisi shoreline (Apulia-Italy). In accordance with the Italian regulations (DPR 470/82), routine detection of Salmonella spp in seawater is only performed when poor hygienic conditions are expected, whereas S. aureus is not a routine parameter. Of the samples tested, 20, 56 and 20 were found unsuitable for TC, FC and FS, respectively. Salmonella spp were isolated in 22 samples. These 14, 7 and 13 had low or absent TC, FC and FS densities. S. aureus was isolated in 41 samples; 16 of these 41 cases were observed in July. Sensitivity was 36.4%, 68.2% and 41% for total and faecal coliforms tests and streptococci test, respectively. Faecal coliforms seem therefore to better predict the presence of Salmonellae in seawater compared with TC and FS. Our data show that the presence of Salmonella spp is not necessarily correlated with great concentrations of faecal pollution indicators; therefore, it would be advisable to always perform the detection of Salmonella spp beside the traditional indicators. We also suggest, in accordance with others authors, including the detection of S. aureus as a supplementary indicator for the prediction of coastal seawater quality and associated health risks