Prevalence, Antibiotic Susceptibility Pattern and the Detection of mecA Gene among Staphylococcus spp. Isolates from a Tertiary Care Hospital in North Karnataka.

To determine the prevalence, antibiotic susceptibility pattern, and screening for the presence of nuc and mecA genes in staphylococcal isolates collected from a tertiary care hospital in North Karnataka. A total of 250 phenotypically confirmed isolates of Staphylococci were collected from October 2021 to March 2022 from (SDMCMS&H), Dharwad. An Antibiogram of all the isolates was recorded followed by their screening for the presence of mecA gene and nuc gene by Multiplex PCR. Based on the susceptibility to cefoxitin discs and biochemical tests, the isolates were categorized as Methicillin-sensitive S. aureus (MSSA-31/250; 12.4%), Methicillin-resistant S. aureus (MRSA-155/250; 62%), Methicillin sensitive coagulase-negative staphylococci (MSCoNS-3/250; 1.2%) and Methicillin-resistant coagulase-negative staphylococci (MRCoNS-61/250; 24.4%). The isolates exhibited high resistance to penicillin (99.2%), oxacillin (90.3%), cefoxitin (86.4%), levofloxacin (81.6%), ciprofloxacin (80.8%) and erythromycin (76.8%). No vancomycin-resistant staphylococci were detected however 12.6% vancomycin intermediate staphylococci were reported. Susceptibility was highest for daptomycin, and tigecycline (100.0%) followed by teicoplanin (90.7%), and nitrofurantoin (85.5%). Among the 250 staphylococcal isolates, 113/186 (60.75%) of the S. aureus and 17/64 (26.6%) CoNS carried the nuc gene. The prevalence of methicillin resistance was higher in CoNS (95.3%) compared to S. aureus (83.3%). Daptomycin, tigecycline, teicoplanin, vancomycin, and nitrofurantoin are the most effective antibiotics against staphylococcal infections. As compared to a similar study previously carried out at SDMCMS&H Dharwad involving 324 isolates of S. aureus, there is a rise of about 49.7% in the frequency of MRSA since 2008.