Comparative study of resistance and virulence markers in Escherichia coli strains isolated from hospital surfaces, clinical specimens and drinking/marine

The aim of this study was the phenotypic analysis of the antibiotic resistance and virulence markers in enterobacterial strains isolated from hospital surfaces, clinical and water sources. In this purpose, 80 enterobacterial strains were investigated for their susceptibility patterns, for the ability to colonize the cellular (HeLa) and inert substrate and for the production of soluble, enzymatic factors. The enterobacterial strains isolated from different sources exhibited different resistance and virulence patterns. The E. coli strains isolated from the hospital environment (both surfaces and clinical sources) exhibited high levels resistance rates to betalactams, including 3rd generation cephalosporins, aminoglycosides, fluoroquinolones, tetracyclines, sulphametoxazole and nalidixic acid, as compared to the aquatic strains with much lower resistance rates, to penicillins, tetracyclines and sulphametoxazole. The majority of the tested strains exhibited ability to colonize the inert and cellular substrate. The hospital strains exhibited the ability to produce a series of soluble enzymes implicated in enteric and extra- intestinal pathogenesis (especially pore forming enzymes, proteases and mucinases). The soluble virulence factors expression in the aquatic strains was much poorer. Our results are demonstrating that E. coli strains isolated from the hospital environment express phenotypic virulence and resistance markers distinct from those observed in the aquatic strains, demonstrating the adaptation of specific phenotypes to specific ecologic niches. However, the aquatic strains could contribute to the increase of resistance and virulence genes reservoirs with potential implication for the human health in the hospital environment, as demonstrated by the presence of resistance markers, especially in the sea water strains and by the high ability to colonize the abiotic and biotic surfaces.