Forty enterococci isolated along the production chains of three traditional cheeses (PDO Pecorino Siciliano, PDOVastedda della Valle del Belìce, and Caciocavallo Palermitano) made in Sicily (southern Italy)were studied for theassessment of their antibiotic resistance and virulence by a combined phenotypic/genotypic approach. A total of31 Enterococcus displayed resistance to at least one or more of the antimicrobials tested. The strains exhibitedhigh percentages of resistance to erythromycin (52.5%), ciprofloxacin (35.0%), quinupristin–dalfopristin(20.0%), tetracycline (17.5%), and high-level streptomycin (5.0%). The presence of tet(M), cat(pC221), andaadE genes for resistance to tetracycline, chloramphenicol, and streptomycin, respectively, was registered in allstrains with resistance phenotype. The erm(B) gene was not detected in any erythromycin-resistant strain. TheEnterococcus strains were further tested by PCR for the presence of virulence genes, namely, gelE, asa1, efaA,ace, and esp. Twenty strains were positive for all virulence genes tested. Among the enterococci isolated fromfinal cheeses, three strains (representing 33.3% of total cheese strains) were sensible to all antimicrobials testedand did not carry any virulence factor. Although this study confirmed that the majority of dairy enterococci arevectors for the dissemination of antimicrobial resistance and virulence genes, only two strains showed a high resistanceto aminoglycosides, commonly administered to combat enterococci responsible for human infections.Furthermore, the presence of the strains E. casseliflavus FMAC163, E. durans FMAC134B, and E. faecium PON94without risk determinants, found at dominating levels over the Enterococcus populations in the processed products,stimulates further investigations for their future applications in cheese making. All strains devoid of the undesiredtraits were isolated from stretched cheeses. Thus, this cheese typology represents an interestingenvironment to deepen the studies on the risk/benefit role of enterococci in fermented foods for their qualifiedpresumption of safety (QPS) assessment.
|Numero di pagine||8|
|Rivista||International Journal of Food Microbiology|
|Stato di pubblicazione||Published - 2016|
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