High prevalence and antimicrobial resistance of mecA Staphylococcus aureus in dairy cattle, sheep, and goat bulk tank milk in Jordan.

The aim of this study was to determine the prevalence and antimicrobial resistance of mecA and mecC methicillin-resistant Staphylococcus aureus (MRSA) in cattle, sheep, and goat dairy farms in Jordan. Milk samples were collected from bulk tanks at 117 dairy farms (44 cattle, 47 sheep, and 26 goat dairy farms) in each region of the country. MRSA were isolated on mecA and mecC chromogenic media and confirmed by PCR. The confirmed isolates were tested for resistance toward 15 antimicrobials by the disc diffusion method. None of the tested bulk milk samples were positive for mecC and 26% (95% CI 20-32%) were positive for mecA MRSA. Specifically, mecA MRSA was detected in 31.8% (95% CI 17.5-46.1) of cattle, 29.8% (95% CI 16.2-43.4) of sheep, and 11.5% (95% CI - 1.6-24.7%) of goat dairy farms. All isolates (n = 86) exhibited resistance to penicillin, oxacillin, cefoxitin; meanwhile, most isolates (70-85%) exhibited resistance toward gentamicin, clindamycin, rifampicin, neomycin, fusidic acid, erythromycin, tetracycline, and ciprofloxacin. All mecA MRSA isolates were resistant to at least one class of antimicrobials. Isolates from all goat milk, 88% of cattle milk, and 87% of sheep milk samples exhibited resistance to three classes of antimicrobials and were considered multidrug resistant (MDR). These data demonstrate widespread MDR MRSA in dairy ruminants in Jordan, and these rates are higher than those reported in other countries. Such high prevalence of MDR MRSA and mecA MRSA could lead to economic losses in the dairy industry in Jordan and poses a possible public health risk.