Molecular characterization of antibiotic resistance in gram-negative bacteria isolated from dairy products

Abstract EN

The present work was carried out on 127 dairy products samples (62 buffalo milk, 46 cow milk, 16 kariesh cheeses and 3 yoghurt) were obtained from retail markets in Dakahlia governorate.

(214) isolates were assayed for antimicrobial susceptibility, the presence of integrons and antimicrobial resistance genes.

152 out of 214 (71.02%) Gram – negative bacterial isolates showed multidrug resistance phenotypes for two or more of the following antimicrobial agents: ampicillin, streptomycin, gentamicin, tetracycline, trimethoprim/ sulfamethoxazole, nalidixic acid, ciprofloxacin, amoxicillin - clavulanic acid , chloramphenicol and cefotaxime .

PCR screening for integrons showed that eight (3.73%) isolates of (Enterobacter aerogens, Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter diversus, Citrobacter freundii, Proteus vulgaris, Escherichia coli and Serratia marsescens) were positive for class 1 integron and all isolates were negative for class 2 integron .β- lactamase resistance gene blaTEM was identified in 6 (2.80%) isolates of (K.

oxytoca , E.

coli , S.

liquefaciens ,E.

cloacae, K.

pneumoniae and C.

diversus).

blaCTX-M was identified in 3 (1.40%) isolates of (E.

coli , K.

oxytoca, and S.

marsescens).

All isolates were negative for blaCMY.

These results highlighted the role of antimicrobial use in dairy animals and development of transferable gene in bacteria in dairy animals from which such genes can be disseminated by horizontal gene transfer to other bacteria and reach human pathogens.