Study on Isolated Staphylococcus aureus from Bovine Milk with Mastitis Containing Methicillin and Panton-Valentine Leukocidin Gene

Abstract

Nowadays, bovine mastitis has been recorded as an inflammation of the mammary gland and Staphylococcus aureus is the main pathogens responsible for contagious mastitis in ruminants. Since milk is an important dairy product, present study seeks to evaluate presence of methicillin-resistant and PVL positive Staphylococcus aureus from bovine milk and evaluate is there any relationship between the presence of genes and antibiotic resistance or not? For this purpose, 100 milk samples were collected from cows affected with mastitis from four dairy farms in Fars province. The samples were transferred to MSA medium and incubated at 37‌° C for 24 hours. The pure colonies were identified by biochemical as well as molecular techniques using mecA, mecC and PVL gene. Then, the antibiotic pattern of the isolates was analyzed based on CLSI 2019 and whonet. Finally, the results were analyzed using statistical analysis. Totally, 6 S.aureus strains were detected which is confirmed by biochemical as well as molecular techniques. The isolates showed different antibiotic susceptibility patterns, most of the isolates were multidrug resistant, while, the strain No. 5 was the most sensitive one. Our results indicated presence of mecA gene in strains 1, 2 and 3, mecC in isolates 4, 5 and 6, and the pvl gene only reported in strain 4. According to the gained results, it could be concluded that, depending on the geographical region there is no relationship between presence of mecA, mecC, and pvl genes with antibiotics pattern.