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 <i>nuc</i> and <i>mecA</i> genes in staphylococcal isolates collected from a tertiary care hospital in North Karnataka. A total of 250 phenotypically confirmed isolates of <i>Staphylococci</i> 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 <i>mecA</i> gene and <i>nuc</i> gene by Multiplex PCR. Based on the susceptibility to cefoxitin discs and biochemical tests, the isolates were categorized as Methicillin-sensitive <i>S. aureus</i> (MSSA-31/250; 12.4%), Methicillin-resistant <i>S. aureus</i> (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 <i>S. aureus</i> and 17/64 (26.6%) CoNS carried the <i>nuc</i> gene. The prevalence of methicillin resistance was higher in CoNS (95.3%) compared to <i>S. aureus</i> (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 <i>S. aureus</i>, there is a rise of about 49.7% in the frequency of MRSA since 2008.