OCCURRENCE AND MOLECULAR CHARACTERIZATION OF EXTENDED SPECTRUM BETA-LACTAMASE PRODUCING Enterobacteriaceae IN MILK AND SOME DAIRY PRODUCTS

In the present study a total of one hundred samples were randomly purchased from different supermarkets in Damietta city, Egypt, including 25 samples each of raw milk, ice cream, Kareish and Domiati cheese. The collected samples were screened initially for cefotaxime-resistant bacteria using selective enrichment. The suspected colonies were further characterized by analysis of resistance genes in ESBL-producing isolates. A total of 59 ESBLs producers colonies (24 from raw milk, 15 from kareish cheese, 13 from Domiati cheese and 7 from ice cream) were recovered and identified as Escherichia coli (n = 29), Klebsiella pneumonia (n = 8), Klebsiella oxytoca (n = 5), Enterobacter aerogenes (n =8), Citrobacter diversus  (n = 8) and Serratia liquefaciens (n = 1). Resistance to two or more antibiotics was observed among the recovered isolates. E. coli isolates showed high resistance pattern against cefaclor (100%), cefoxitin (100%), cefalaxim (96.5%), ceftazidime (93%), pencillin (93%) and 79% for Pipercillin/Tazobactam. All the recovered Klebseilla spp. isolates were resistant to Cefepime and Pipercillin/Tazobactam (84.6% each) and exhibited 100% resistant to other antimicrobials agents. Meanwhile, all the recovered isolates were sensitive to imipenem and meropenem. Gene encoding blaCTX-M1 was mostly predominant among screened genes, being present in 13 (48%) dairy samples for blaTEM and blaSHV, they were detected in 12 (44%) and 4 (14.8%) isolates, respectively. In conclusion, there is clear evidence of circulation of antibiotic-resistant food borne ESBL producing Enterobacteriaceae in the examined dairy samples. The concern about increasing the risk of dissemination of such multi-drug resistant pathogens rises with a potential asymptomatic colonization and complication of systemic infection in human subjects. There is also a possible interface for the exchange of resistance genes within and across species and with commensal bacteria of the human and animals.Key words: dairy products; ESBL producing Enterobacteriaceae; Egypt; public health