Repurposing of non-steroidal anti-inflammatory drugs for combination therapies to combat multidrug-resistant S. aureus of bovine reproductive tract origin

Multidrug-resistant bacteria have become the predominant etiology in bovine female reproductive tract infections and thus require effective treatment approaches. The main goal of this study was the molecular detection of mec A , bla Z , tet K , and aac A -aph D genes in Staphylococcus aureus ( S. aureus ) responsible for methicillin, beta-lactam, tetracycline, and aminoglycoside resistance respectively. Phylogenetic analysis was conducted to check the homology of staphylococcal genes with NCBI sequences. The in-vitro efficacy of non-steroidal anti-inflammatory drugs (NSAIDs) in combination therapies against MDR S. aureus was evaluated using well diffusion assay and checkerboard method. Vaginal swab samples (n = 384) collected from bovines suffering from endometritis, pyometra, and retained placenta were tested for S. aureus . Results showed a 17.96% overall prevalence . Both phenotypic and genotypic resistance was observed among S. aureus isolates with 50.72% and 37.68% isolates being confirmed as methicillin-resistant (MRSA), 36.23% and 18.84% isolates exhibiting beta-lactam, 40.58%, and 27.54% isolates showing tetracycline, and 33.33% and 36.23% isolates showing aminoglycosides resistance based on disc diffusion and gene confirmation, respectively. Phylogenetic analysis indicated homology with previously reported Pakistani isolates suggesting the possibility of MDR S. aureus transmission within and between animals. Synergy testing indicated that combinations of ceftriaxone-ketoprofen (153.77%), ceftriaxone-meloxicam (149.55%), amoxiclav-flunixin meglumine (106.06%), and oxytetracycline-flunixin meglumine (104.47%) showed synergy on well diffusion assay. Based on the fractional inhibitory concentration index by checkerboard method, oxytetracycline-meloxicam and gentamicin-ketoprofen combinations exhibited synergistic interaction. In conclusion, MDR S. aureus resistance was mitigated in-vitro through the combination of antibiotics (oxytetracycline, gentamicin) with NSAIDs (meloxicam, ketoprofen) that could be used to create therapeutic strategies for bovine reproductive issues.