ANTIBIOTIC-RESISTANCE GENES IN COAGULASE-NEGATIVE STAPHYLOCOCCI ISOLATED FROM FOOD

Coagulase-negative staphylococci were isolated from different raw milk cheeses and raw meat products and screened for their antibiotic resis tances. They were identified as Staphylococcus xylosus, S. lentus, S. caprae, S. epidemidis and S. haemolyticus, The most frequent resistanc es found were those to chloramphenicol, tetracycline, erythromycin and lincomycin. They have been characterized on the molecular level. The chloramphenicol resistance genes were localized in several S. xylosus and S. caprae on plasmids with sizes ranging from 3.8-kb to 4.3-kb and were identified as chloramphenicol acetyltransferase (cat). All the t etracycline resistant strains were identified as S. xylosus and harbou red a 4.4-kb plasmid carrying the tetracycline efflux resistance gene (tetK). The two erythromycin/lincomycin resistant S. caprae and S. epi dermidis strains did not hybridize with the MLS, resistance genes ermA M, ermA, ermB and ermC. Three erythromycin resistant Staphylococcus sp . strains harboured an erythromycin efflux resistance gene (msr) local ized twice on a 18-kb plasmid and or ce on the chromosome. A S. haemol yticus strain showing resistance to both lincomycin and clindamycin ha rboured a linA gene-carrying 2.2-kb plasmid. Further resistances to ge ntamicin, penicillin and kanamycin were less frequently observed and p et not characterized on a molecular level.