Clinical Mastitis Caused by Methicillin-resistant Staphylococcus aureus in a Heifer

Emergence of methicillin-resistant Staphylococcus aureus among bovine mastitis is the major cause of frequent therapeutic failure and a cause of concern for veterinary practitioners. The current study describes a case of heifer mastitis caused by the isolates of the methicillin-resistant S. aureus. On the 24th day of postpartum, the right hind quarter of the heifer was shown clinical mastitis, isolate and cultivate the pathogens in milk, and confirmed the bacterial was methicillin-resistant Staphylococcus aureus by PCR the 23S rRNA and mecA gene and antimicrobial susceptibility tests. The MRSA were resistant to penicillin, ampicillin, cefazolin, gentamicin, erythromycin, and trimethoprim/sulfamethoxazole. The heifer was treated with Chinese medicine Ruyanxiao twice a day for 5 days, and the symptoms disappeared and CMT score was 0. This article is the first report of the occurrence of mastitis caused by methicillin-resistant Staphylococcus aureus in Holstein heifer.