Background: Infections with Staphylococcus aureus cause significant morbidity and mortality worldwide. Resistant strains of S. aureus to commonly used antibiotics are being increasingly encountered in clinical practice, necessitating the need to determine the resistance pattern in Nigeria.
Methods: Antibiotic susceptibility testing was performed on 360 S. aureus isolates from clinical specimen from seven hospitals across the six geo-political regions of Nigeria using Kirby Bauer disc diffusion technique, and E-test for vancomycin. Cefoxitin 30 μg disc was used to determine methicillin resistance, and D-test for inducible clindamycin resistance.
Results: Methicillin-resistant S. aureus was confirmed in 176 (48.9%) of the isolates, 346 (96%) for penicillin G and 311 (86.4%) for trimethoprim. 175 (99.4%) of the 176 resistant to methicillin were susceptible to vancomycin. Linezolid, tigecycline, chloramphenicol and clindamycin had susceptibilities of 341 (94.7%), 332 (92.2%), 298 (82.8%) and 290 (80.6%) respectively. Inducible clindamycin resistance was elucidated in 25 (29.1%) of the 86 isolates. Generally, MRSA isolates were more resistant than methicillin-sensitive S. aureus (MSSA) to all antibiotics tested.
Conclusion: Staphylococcus aureus rates of resistance are high and call for urgent action such as antibiotic stewardship programmes and periodic surveillance to enhance clinical outcomes. While targeted therapy is preferred, options for empiric treatment include chloramphenicol, clindamycin, linezolid or vancomycin.
Keywords: Methicillin resistance; Nigeria; Staphylococcus aureus; Surveillance.