Antibiotic susceptibility of Lactococcus isolated from Turkish raw milk cheeses

Abstract

Lactococcus lactis strains isolated from traditionally produced Turkish White Pickled (22 strains) and Kashar cheeses (18 strains) were examined for susceptibility to a range of antibiotics, including ampicillin, amoxicillin/clavulanic acid, vancomycin, oxacillin, penicillin G, cefotaxime, ciprofloxacin, gentamicin, streptomycin, tetracycline, erythromycin, trimethoprim, chloramphenicol, clindamycin and rifampicin, by the disc diffusion method. Susceptibility to ampicillin, amoxicillin-clavulanic acid, vancomycin and chloramphenicol, and resistance to oxacillin antibiotics were observed in all strains tested. The susceptibility to the other antibiotics was variable and strain-dependent. Only one strain exhibited resistance to erythromycin. All strains were resistant to more than one of the antibiotics tested, and the greatest number of strains were resistant to oxacillin, ceftazidime, streptomycin and clindamycin. A multiple antibiotic resistance profile revealed that most of the strains (92.5%) were resistant to three to seven antibiotics, whereas one strain demonstrated resistance to two antibiotics. The highest resistance was found in two strains isolated from White Pickled cheese, of which one was resistant to eight and the other to nine antibiotics. Our findings reveal a high level of antibiotic resistance among the strains of L. lactis and emphasize the need for prudent use of antibiotics.