Isolation and identification of Staphylococcus aureus obtained from cheese samples

Abstract

Milk and dairy products including cheese are one of the most significant food commodities in terms of the food industry. However, a contaminated food product could conduce a variety of food borne bacterial infections. Although Staphylococcus aureus is known as normal flora members of the humans, it`s often isolated from the community and hospital-acquired infections. Therefore, investigation of Staphylococcus aureus from cheese samples was aimed in this study. A total of nineteen (n=19) white cheese was collected from various outdoor markets in Istanbul. All cheese samples were evaluated quantitatively. Phenotypic identification tests including Gram staining, oxidase, catalase, mannitol, and DNase were performed. The presumptive Staphylococcus aureus colonies (n=47) were analyzed by the 16S rRNA PCR and sequencing. And the sequences were deposited into the National Center for Biotechnology Information. According to the nucleotide BLAST analysis, a total of 47 Staphylococaceae and Enterococcaceae members including Staphylococcus aureus (n=3), Staphylococcus carnosus (n=1), Macrococcus caseolyticus (n=1), Enterococcus faecalis (n=25), Enterococcus faecium (n=12), Enterococcus durans (n=4), and Enterococcus gallinarum (n=1) were identified. Regarding methicillin susceptibility testing, two of out of three Staphylococcus aureus were detected as methicillin-resistant.