INCIDENCE, BIOCHEMICAL CHARACTERISTICS AND ANTIBIOTIC RESISTANCE OF Enterobacter sakazakii ISOLATED FROM MILK AND DAIRY PRODUCTS

Document Type : Original Article

Authors

1 Food Safety and Microbial Physiology Laboratory, Dairy Dept., Fac. of Agric., Mansoura University

2 Faculty of Tourism and Hotels, Mansoura University.

Abstract

During the course of this study, 235 samples of raw milk, dried milk and some local dairy products were collected from eight Egyptian governorates and  examined for the presence of the emergent pathogen Enterobacter sakazakii. Out of 235 examined samples of milk and dairy products, 16 suspect isolates of Ent. sakazakii were recovered, of which only 6 isolates were confirmed as belonging to this pathogen. Confirmed Ent. sakazakii isolates were recovered from dried milk (2 isolates), stored Domiati cheese (2 isolates) and fresh Domiati cheese (2 isolates). Other examined samples including those of raw milk, Ras cheese, Kariesh cheese, and yoghurt were free of the  pathogen. Biochemical characterization of Ent. sakazakii isolates using the Api 20E miniaturized identification system showed that these isolates had the typical biochemical traits previously reported for this species. These isolates expressed, however, variable reactions in the ornithine decarboxylase and voges-proskauer tests. The isolates were found to be susceptible to 11 antibiotics including ampicillin (10 mg), ciprofloxacin (5mg), chloramphenicol (30 mg), nalidixic acid (30 mg), tetracycline (30 mg), spiramycin (100 mg), carbenicillin (100 mg), penicillin (100 unit), colistin sulphate (10 mg), cephradine (30 mg) and gentamicin (10 mg). Overall, these results confirmed the association of  Ent. sakazakii with dried milk and certain dairy products such as Domiati cheese, but at generally limited incidence rates. The current results also show that it is possible to eradicate Ent. sakazakii using currently available generations of antibiotics.