Antimicrobial Resistance Properties, Biofilm, and mecA Gene Presence in Staphylococcus Aureus Isolated from Raw Milk Sold in Van, Türkiye

Abstract

Staphylococcus aureus can cause foodborne poisoning and can form biofilms, reducing enterotoxin production and the penetration rate of antibiotics. Therefore, infections and poisonings caused by S. aureus can be difficult to treat. The aim of this study was to investigate the antibiotic resistance levels of S. aureus isolates obtained from raw milk and the presence of biofilm and mecA gene and to reveal the risk to public health. S. aureus was isolated in 30 (30%) of 100 raw milk samples obtained from Van province. A total of 48 S. aureus isolates were obtained from 30 samples. All 48 isolates (100%) obtained were resistant to penicillin G and cefoxitin, 4 (8.33%) to sulfamethoxazole-trimethoprim and chloramphenicol, and 25 (52.08%) to erythromycin. All of the isolates (100%) were found to be susceptible to ceftriaxone. In addition, 26 (54.16%) of the obtained isolates were found to be resistant to at least 3 antibiotics. The strains found to be resistant to penicillin and cefoxitin were also intermediate to at least one of the antibiotics. Biofilm genes were detected in 18 of the S. aureus isolates (37.5%). Twelve of the biofilm-forming isolates contain icaA (66.6%), 3 contain icaD (16.6%) and the other 3 contain bap genes (16.6%). Three of the isolates contain icaA and icaD genes and the other three isolates contain icaA and bap genes together. It was determined that only 2 of the isolates contained the mecA gene. The isolates containing the mecA gene also contained the icaA and icaD genes. In conclusion, the fact that S. aureus isolates had high antibiotic resistance, biofilm-forming genes, and methicillin resistance genes showed that raw milk may be a serious public health problem.