Relative prevalence of methicilline resistant Staphylococcus aureus and its susceptibility pattern in Mulago Hospital, Kampala, Uganda.

Methicilline resistant Staphylococcus aureus (MRSA) strains are becoming increasingly multiresistant, and have recently developed resistance to vancomycin, which has been used successfully to treat MRSA for many years. In-vitro determination of resistance patterns of S. aureus is critical in terms of administering suitable antimicrobial treatments. The objective of this study was to determine the relative prevalence of MRSA among S. aureus isolates from surgical site infections and their antibiotic susceptibility pattern in Mulago Hospital, Kampala, Uganda. One hundred eighty eight pus swabs were collected from patients with surgical site infections. Swabs were inoculated for culture at the Microbiology Laboratory of the Faculty of Medicine, Makerere University. S. aureus isolates were identified using standard procedures and tested for oxacillin resistance according to methods of the National Committee for Clinical Laboratory Standards. Out of the 188 specimens, 54 (28.7%) grew S. aureus. Seventeen (31.5%) of the S. aureus isolates were confirmed as MRSA by PCR. Resistance rates of MRSA were 88.2% for trimethoprim-sulfamethoxazole, 88.2% for erythromycin, 58.8% for gentamycin, 70.6% for ciprofloxacin, and 88.2% for chloramphenicol. All isolates were found to be sensitive to vancomycin and clindamycin though the D-test was found to be positive in 82.4% of the isolates. In our region, although methicillin resistance increased in S. aureus strains, because of the unavailability and the high cost of alternative antibiotics, gentamycin is still suggested as an alternative for treatment of S. aureus infections. These results however indicate that vancomycin seemed to be the only antimicrobial agent effective against MRSA and it could be the drug of choice in treating multidrug resistant MRSA infection.