Staphylococcus aureus infections and their antibiotic susceptibility profile at a tertiary care hospital

Objective: Staphylococcus aureus remains an important bacterial pathogen causing diverse infections which are both nosocomial and community acquired. Increasing resistance among S. aureus to various antibiotics is a cause of concern. Methods: A prospective observational study of 4 months duration was conducted to analyze the spectrum of infections caused by S. aureus and to study its antimicrobial resistance to commonly used antibiotics. Specimens from various clinical sites received in the laboratory for culture and sensitivity were processed as per standard techniques. Identification and susceptibility testing of S. aureus isolates were done using automated systems. Results: A total of 234 S. aureus isolates were obtained during the study period. Males accounted for 70.1% (n=164) of patients with S. aureus infections. These patients were uniformly distributed across all age groups. S. aureus was most commonly isolated from pus and exudates (64.5%) followed by respiratory specimens (20.5%) and mainly cultured from the skin and soft tissue infections (56%). Methicillin-resistant S. aureus (MRSA) accounted for 47% (n=110) of isolates. Higher rates of susceptibility were noted for tetracycline (95.3%), gentamicin (85.4%), and trimethoprim/ sulfamethoxazole (88%). Low susceptibility rate was seen for ciprofloxacin (11.2%). Inducible clindamycin resistance was seen in 22.4% (n=50) isolates. Methicillin-sensitive S. aureus isolates were found to be more susceptible to non-beta lactam antibiotics than the methicillin-resistant isolates. Conclusion: A high frequency of MRSA was found in our study. Regular surveillance of antimicrobial resistance profile of this most frequent pathogen is necessary to aid in providing appropriate empirical antibiotic therapy.