Antibiotic Resistance of Enterococcal Isolates in Raw Milk

In the present study, 177 Enterococci isolated from 78 raw milk samples were identified by the API 20 Strep system and conventional biochemical tests. Enterococcus faecalis (54.2%) and E. faecium (29%) were the most frequently isolated species, followed by E. durans (6.2%), E. hirae/dispar (5.0%), E. gallinarum groups (3.0%), E. mundtii (2.2%) and E. raffinosus (0.5%). A disk-diffusion method was applied to assay in vitro activity of antibiotics against Enterococcal isolates obtained from raw milk. There was a high frequency of oxacillin, streptomycin and erythromycin (E) resistance in enterococcal isolates (95, 97 and 86%). Vancomycin (VA) and teicoplanin resistance was observed in 48 and 52% of E. faecalis isolates, respectively. The corresponding values were 26 and 33% for E. faecium. Resistance to VA was significantly associated to E, rifampin, gentamycin, ampicillin and ceftriaxone resistance. Implications and public health aspects of antibiotic resistance, especially VA-resistant Enterococci in food, are discussed.