SCCmec typing of Staphylococcus aureus strains isolated from milk and dairy products

Staphylococcus aureus is a major opportunistic pathogen causing various diseases such as pneumonia and urinary tract infections. Indiscriminate and excessive use of antibiotics leads to antibiotic resistance in this bacterium, especially against commonly used antibiotics in the treatment. The present study aimed to evaluate the antibiotic resistance pattern of Staphylococcus aureus strains isolated from milk and traditional milk products, especially resistance to methicillin. A total of 403 samples of milk and milk products was examined and collected from distribution centers of traditional and dairy products. Strains isolated were tested by PCR to determine the frequency of mec gene, SCCmec types and genes coding for antibiotic resistance. Antibiotic resistance pattern of isolates was assessed by disk diffusion method. Out of 403 samples, 151 samples (%44.67) were infected with Staphylococcus aureus, and the highest prevalence of infection was found in samples of cow raw milk (%58.55). Only IV type was detected in mecA-positive isolates among SCCmec types; a number of 66 isolates belonged to IVd type, 21 isolates related to IVc type and 13 isolates belonged to IVa type and the significant differences between SCCmec type IVd with two types IVc and IVa was observed. The high prevalence of infection with Staphylococcus aureus in raw milk and traditional milk products and high antibiotic resistance of the isolates to common types of antibiotics in treating human infections are serious warning to the community and it requires hygienic measures and quality control of dairy products more than ever.