Investigation of Contamination Rate and Determination of Pattern of Antibiotic Resistance in Coagulase Positive Staphylococcus aureus Isolated from Domestic Cheeses in Maragheh, Iran

 The aim of this study was investigation of contamination rate and determination of pattern of antibiotic resistance in coagulase positive Staphylococcus aureus isolated from domestic cheeses in Maragheh, Iran.

In this experimental study, 100 traditional white brine cheese samples were collected from different villages of Maragheh with the observance of aseptic principles and transferred to microbiology laboratory of Islamic Azad University, Maragheh branch. The samples were cultured in specific media and the complementary biochemical tests were done for the identification of coagulase positive Staphylococcus aureus. For molecular diagnosis of S.aureus, these isolates were identified as S.aureus with the proliferation of Thermonuclease species-specific gene (nuc) by polymerase chain reaction (PCR) method. Cheese samples were tested for pH and NaCl content. The susceptibility of all isolates to different antibiotics was evaluated by kirby-bauer’s method.

Of 100 samples taken from villages of Maragheh, 21 samples (21%) were identified as Staphylococcus aureus coagulase positive. 20 isolates were resistant to more than one antibiotic. The most resistance of isolates were to penicillin, vancomycin, and methicillin, respectively. No significant difference was shown among old and fresh samples in Staphylococcus aureus incidence (p>0.05).

Considering the high contamination rate of domestic cheese by coagulase positive Staphylococcus aureus in Maragheh, the production and distribution of these cheeses should be under hygienic situations. Efficient informing about the potential risk of using these products seems necessary.