Water quality assessment of transitional and coastal marine Sicilian waters (Italy): Ecological and epidemiological significance of multiple antimicrobial resistant Enterococcus spp.

Abstract

The water quality of Sicilian transitional and coastal marine areas was investigated by evaluating the distribution of Enterococcus spp.; as a reference, two sewage samples were also analysed. The epidemiological implications of their presence were considered. Enterococcal strains isolated by culture methods were phenotypically and molecularly identified and their susceptibility to antibiotics tested. High phenotypic variability was detected, with low specific identification for 46% of the isolated strains. E. casseliflavus, isolated from transitional environments only, predominated; in coastal and sewage waters E. faecium prevailed, occurring also in transitional environments, where multiple antibiotic resistances were found. Ampicillin and vancomycin resistant enterococci were isolated exclusively from transitional environments. The dynamics of dissemination of antibiotic resistant enterococci in aquatic environments located across the South-North migration route of many wild birds could be very complex, emphasising the relevance of epidemiological studies on transitional aquatic environments as reservoirs of pathogenic enterococci, as well as on sedentary seagulls and migratory wild birds as carriers and spreaders of antibiotic resistant enterococci.