Bacteriological and virological quality of seawater bathing areas along the Tyrrhenian coast

Abstract

Monitoring was carried out during summer 1997 along a selected area of the Tyrrhenian coast near the Tiber river mouth. Fifty-eight seawater samples, collected from 19 stations, were examined for coliforms, streptococci, Enteroviruses, Salmonellae, coliphages, Bacteroides fragilis phages, Pseudomonas, alophilic Vibrios, Aeromonas and yeasts. Salmonellae and coliphages were isolated in 3 and 12 out of 58 samples, respectively. Enteroviruses and Bacteroides fragilis phages were not isolated. Reoviruses were isolated only from 2 out of 58 samples. A limited number of samples of the northern stations located near the Tiber and other river mouths exceeded the guide values for bathing water by the EU Directive. All the southern stations, located near canals, were of very good microbiological quality. Pseudomonas, Vibrio, Aeromonas and yeasts were isolated from all stations and their values in 100 ml of seawater were 10-10 6 , 10-10 6 , 0-10 6 and 1-10 3 , respectively. An extensive disinfection practice carried out on domestic wastes, which are discharged in rivers and canals, probably brought pollution levels of most stations to values within the bacterial standards. The spread of Pseudomonas, Aeromonas, etc. showed that all the coastal area studied was characterized by the presence of organic matter coming from land that can support the presence of opportunistic pathogens and other microbial flora.