Title : Molecular identification, antimicrobial resistance and virulence gene profiling of diverse Staphylococcus Spp,involved in bovine sub-clinical mastitis, Bangladesh
Abstract:
This study was conducted to detect the diverse Staphylococcus spp. involved in bovine sub-clinical mastitis (SCM) with their antimicrobial resistance profile, methicillin resistant and virulence genes, and associated risk factors. Standard classical bacteriological methods and polymerase chain reaction was performed for confirmation of Staphylococcus spp., resistant and virulence genes. A total of 284 lactating cows within 30 dairy farms were screened, of them 178 (62.68%) cows were found affected with SCM. S. chromogenes 117 (65.73%) was found to be most predominant, where S. aureus 28 (15.73%), S. haemolyticus 34 (19.10%), S. epidermidis 36 (20.22%), and S. sciuri 10 (5.62%) were isolated from SCM cows. S. aureus and S. sciuri displayed the highest resistance against ampicillin (82.14% and 80%, respectively) and amoxycillin/clavulanic (75% and 70%, respectively). In addition, S. chromogenes, S. haemolyticus, and S. epidermidis showed maximal resistance against cefepime, which were 95.73%, 94.12%, and 97.22%, respectively. Surprisingly, all five staphylococcus species were found multi-drug resistant (MDR) (i.e. resistant to ≥ 3 antimicrobial classes). Notably, 9 (32.14%) S. aureus, 7 (5.98%) S. chromogenes, 2 (5.56%) S. epidermidis, and 1 (10.0%) S. sciuri harbored the mecA gene. Moreover, 20.0% S. sciuri and 17.65% S. haemolyticus carried the cytotoxin (pvl) gene, while 14.29% S. aureus encoded the toxic shock syndrome toxin (tst) gene. Multivariable logistic regression analysis identified the following variables as risk factors for bovine SCM: “Old aged cow” (p <0.05); “Early stage of lactation” (p <0.02) and, “Firm udder condition” (p <0.02) for S. aureus, S. chromogenes, S. haemolyticus, respectively.
Keywords: SCM, Staphylococcus spp., MDR, mecA gene, Virulence genes, Risk factors
