Prevalence of Methicillin Resistant Staphylococcus aureus among Isolates from Wounds in Surgical Wards at Kabale Regional Referral Hospital, South Western Uganda

Background: Methicillin resistant S. aureus (MRSA) is a multidrug resistant organism that threatens the continued effectiveness of antibiotics worldwide and causes a threat almost exclusively in hospitals and long-term care settings. This study sought to determine the prevalence and antimicrobial susceptibility pattern of MRSA at Kabale Regional Referral Hospital (KRRH) in South Western Uganda.

Methods: This was a cross sectional study conducted between June and November 2014 involving 350 pus swabs from infected surgical sites. The samples were cultured on Mannitol salt agar at 37°C for 17- 24 hours and the colonies were tested and confirmed as S. aureus using API staph testing kit. Screening for MRSA was performed using the Cefoxitin (30 µg) disc on Muller Hinton agar medium. MRSA susceptibility was performed by the Kirby Bauer disc diffusion on MHA for the following antibiotics: Ceftriaxone, Ciprofloxacin, Erythromycin, Imipenem, Trimethoprim – sulfamethoxazole, Levofloxacin and Gentamycin. The zones of inhibition were measured using a ruler and compared with the CLSI guidelines 2012.

Results: From the 350 pus swabs, 331 isolates of S. aureus were obtained, of which 179 (54%) isolates were Methicillin resistant. Majority (54%) of the MRSA isolates were highly sensitive to Gentamycin and Levofloxacin but highly resistant to Ceftriaxone (100%), Imipenem (100%), Trimethoprim – sulfamethoxazole (85%), and Erythromycin (67%).

Conclusion: The prevalence of MRSA in KRRH is high with high resistance to Ceftriaxone, Imipenem, Trimethoprim – sulfamethoxazole and Erythromycin. However, good sensitivity to gentamycin and Levofloxacin is still observed.