Comparative Survival of Faecal and Human Contaminants and Use of Staphylococcus aureus as an Effective Indicator of Human Pollution

Comparative survival tests of faecal coliforms (FC), faecal streptococci (FS), Salmonella spp. and Staphylococcus aureus grown in sea (35‰ of salinity) and brackish water (27‰ of salinity) were performed in the dark at room temperature (22 ± 2°C). In seawater T90 was: S. aureus > FS > Salmonella spp. > FC. Survival in brackish water generally appeared to be higher than in seawater; in particular this increased from 48 to 72 h, from 88 to 104 h and from 56 to 80 h, respectively for FC, FS and Salmonella spp. A lower salinity had no effect on the survival rates of S. aureus whose T90 remained stable (96 h). FC proved to be the most sensitive bacteria to salinity and S. aureus the most adaptable one. There should be caution in interpreting these data; however it seems that S. aureus could be an effective indicator of human pollution and that the microbiological parameters used for the control of seawater could be reconsidered.