Molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA)isolated from bovine wounds

Abstract

Staphylococcus aureus (S. aureus) is a Gram-positive coccus with golden-colored colonies 0.5-1.5 ?m in diameter. It is an opportunistic pathogen and colonizes as healthy flora. When the host defense system is breached it provides a source for the introduction of (Methicillin-resistant S. aureus) MRSA. The incorporation of the mecA gene shift S. aureus into MRSA, mecA is a primary gene for the confirmation of MRSA, so, it is used as a useful marker to determine Methicillin resistance in S. aureus. In this study, we investigated the molecular characterization of mecA, Panton-Valentine Leukocidin (PVL), and 16S rRNA genes in MRSA to determine diversity, phylogenetic analysis, and multidrug resistance (MDR) of MRSA isolated from chronic bovine wounds. A total of 8 antibiotics were used for MDR profiling and the results obtained are as follows: 100% of MRSA isolates were resistant to Augmentin and Cefipime, 81.8% to Vancomycin and Tetracyclin, 36.4% to Streptomycin and Ciprofloxacin, Azithromycin 54.5 and 0% to Chloramphenicol which warrants that it?s the best antibiotic according to this study. Multiplex PCRs were performed for the confirmation of targeted genes and diversity analysis. The diversity of MRSA in the bovine population was 22% (11/50) on the microbiological scale that considered high as compared to reported data. When the PCR of MRSA isolates was performed, there was a unique phenomenon observed i.e., no mecA gene was present in 2 isolates 18.18% (2/11) which connotes the importance of molecular methods/PCR for the identification of microbes. The prevalence of the PVL gene was 18.18%, comparatively high as compared to previous studies conducted on bovine chronic wounds. When the Sanger sequencing of 16S rRNA of MRSA isolates was performed there was a change of one nucleotide identified (C>T) at position 1031. After performing phylogenetic analysis with S. aureus of different countries distinct and separate dendrogram was obtained which differentiates the Pakistani S. aureus isolates from other countries.