Antibiotic resistance of generic Escherichia coli and Staphylococcus aureus isolated from cheese samples sold in retail markets and correlation between antibiotics used as preventative and therapeutic measures in mastitis

Cheese is one of the most popular protein sources. Food pathogens can easily cause infections when consumed without applying the food to necessary procedures. Thus, as being the first step of cheese production, farm and milking hygiene are very important in the milk production process. Regarding milking hygiene, antibiotic application is a common procedure during the dry period in preservation of dug health. The antibiotics administered are found to trigger an antibiotic resistance in the micro flora of the animals.In this study, the effect of commonly used antibiotics on E. coli and S. aureus, two organisms that play a major role in mastitis, and the evaluation of potential public health risks with cheese infected with these two bacteria.Feta and yellow cheese samples of 50 units each were used. Isolations of E. coli and S. aureus were done with ISO 16649-2 (2001) and TS 6582-1 EN ISO 6888-1 (2001), respectively. Following confirmation of the isolates antibiogram testing were done against the most commonly used antibiotics found as a result of a survey conducted on 30 veterinarians.Of the feta cheese %22 and %16were contaminated with E. coli and S. aureus, respectively and only %4 of the yellow cheese was found to be contaminated with S. aureus. Following the antibiogram testing to the isolated E. coli strains, penicillin, streptomycin, gentamycin, amoxicillin-clavulanate and enrofloxacin resistances were found to be %100, %55, %55, %18 and %0, respectively. Following the antibiogram testing to the isolated S. aureus strains, penicillin, streptomycin, gentamycin, amoxicillin-clavulanate and enrofloxacin resistances were found to be, %12,5, %37,5, %37,5, %12,5 and %25, respectively. These results and resistance rates indicates significant resistance against the commonly administered antibiotics used for prophylactic purposes in dry period mastitis treatment on the field.Milk is an important food for microorganisms for contamination, survival and reproduction, and antibiotics concentrated in it can trigger resistance in the present flora. Although treated with various procedures, always having the risk of contamination and high antibiotic resistance, such milk samples may result with adverse outcomes on public health. Supplementary preventive measures should be taken against contamination in milk production. Additionally, antibiotics should be used wisely with consideration of half-life times in order to prevent resistance and avoid the clinical picture of a nation-wide health and economical problem.