Restriction Fragment Length Polymorphism Typing of Staphylococcus aureus Strains Isolated from Bovine Mastitis and Dairy Products in Ahvaz, Iran, Using of Digested Coagulase Gene

Staphylococcus aureus is a major pathogen in the transmission of diseases from animals to humans and vice-versa.Various infections, such as mastitis in cattle, sheep and goats, as well as gastroenteritis due to food poisoning in humans are the most frequent problems caused by S. aureus. The bacteria also lead to severe economic losses in dairy industry. A major virulence factor for the organism is encoded by the coagulase (coa) gene. This study aimed to assess the polymorphisms of the coa gene in S. aureus strains isolated from bovine mastitis and dairy product samples in Ahvaz, Iran. The results showed that out of 91 S. aureus, 80 (87.91%) isolates were positive for coa gene(s). In total, nine different polymerase chain reaction (PCR) products were obtained for coa-positive isolates. A single band was detected in coa PCR with a size ranges from 370 to 830 bp in most isolates (n=77, 96.25%). For three isolates (3.75%), two amplification products were obtained. A PCR product of an estimated size of 590 bp was most frequent, as obtained for 48 (60.00%) isolates. Whereas, 370 and 830 bp PCR products were the least presented, for two (2.50%) and one (1.25%) isolate, respectively. Subsequently, for restriction fragment length polymorphism (RFLP), typing of coa gene and AluI restriction enzyme were used for the digestion of the products. AluI for most of PCR products generated a unique pattern; however, four PCR products (the sizes ranged 750, 670, 590, and 510 bp) generated three or more patterns. Based on AluI RFLP of coa gene, the isolates were classified into 23 groups. Two groups of isolates were dominant, making 45% of the total. According to the findings, one or two types of coa RFLP were dominant among samples that were infected with more S. aureus isolates belonging to different coa RFLP types.