Identification and evaluation of antimicrobial resistance of enterococci isolated from raw ewes’ and cows’ milk collected in western Sicily: a preliminary investigation

Abstract

The present work was carried out to investigate the Antimicrobial Resistance (AMR) of enterococci isolated from raw ewes’ and cows’ milk. The samples were collected from eighteen semi-extensive dairy sheep and cow farms throughout western Sicily. Plate counts, carried out on Rapid Enterococcus Agar commonly used to detect food enterococci, revealed a maximal enterococcal concentration of approximately 4.58 Log Colony Forming Unit (CFU)/mL. Colonies were isolated and differentiated based on genetic analysis by Randomly Amplified Polymorphic DNA (RAPD)-PCR. Thirty-eight different strains were identified. Analysis by a species-specific multiplex PCR assay grouped the strains into three Enterococcus species such as Enterococcus durans, Enterococcus faecalis and Enterococcus faecium. The 38 strains were also investigated for their antimicrobial resistance by a phenotypic approach. All 38 Enterococcus displayed resistance to at least one or more of the antimicrobials tested confirmed that the dairy enterococci could be a vector for the dissemination of antimicrobial resistance. This work showed that enterococci with AMR traits are commonly present in semiextensive dairy sheep and cow farms of western Sicily pointed out the relevance of informing dairy makers and veterinary regarding the antimicrobial use in order to mitigate problems of public health and veterinary medicine.

Keywords

• Enterococcus; antimicrobial resistance; sheep milk; cow milk