Characterization of methicillin-resistant Staphylococcus aureus from skin and soft tissue infections in patients in Nairobi, Kenya

Abstract

Background: Skin and soft tissue infections (SSTIs) are among the most common infectious diseases and a frequent cause of hospital visits. In this study we sought to assess the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and antibiotic susceptibility patterns in SSTIs in patients attending hospitals in Kenya. Methods: Eighty-two S. aureus isolates recovered from SSTIs from both inpatients and outpatients were screened for antibiotic susceptibility, possession of staphylococcal cassette chromosome mec (SCC. mec) gene type, and the Panton-Valentine leukocidin (PVL) toxin gene. The prevalence of MRSA was investigated in relation to the type of patient and infection type, as well as the type of health care facility. Results: Of 60 boil cultures, 39 (65%) grew S. aureus, of out of which 34 (87.2%) were MRSA. Of the 60 abscess cultures, 14 (23.3%) grew S. aureus, of which 10 (71.4%) were MRSA. Of 34 cellulitis cultures, 18 (52.9%) grew S. aureus, of which 16 (88.8%) were MRSA. Of 25 ulcer cultures, 11 (44%) grew S. aureus, of which nine (81.8%) were MRSA. Sixty-nine of 82 S. aureus (84.1%) were MRSA, with 52 (75.4%) possessing SCC. mec II type and 14 (20.3%) being positive for the PVL gene. Based on hospitals, it was noted that most MRSA were isolated at publicly funded health care facilities serving an economically disadvantaged segment of Nairobi's population, such as those living in urban informal settlements. All 82 S. aureus were susceptible to vancomycin and resistant in high numbers to macrolides, aminoglycosides, and quinolones. Bacterial isolates were mostly susceptible to vancomycin, ciprofloxacin and co-trimoxazole, and none was resistant to vancomycin. However, most organisms showed decreased susceptibility to erythromycin and clindamycin. Conclusions: These findings suggest that SCC. mec II MRSA and a PVL strain of MRSA are significant pathogens in patients with SSTIs presenting to hospitals in Kenya, and that MRSA cases are prevalent at publicly funded health care facilities. © 2012 International Society for Infectious Diseases.