Prevalence and antimicrobial susceptibility pattern of Staphylococcus Aureus isolated from clinical specimens at the Mater Hospital Nairobi, Kenya.

Abstract Staphylococcus aureus (S. aureus) is a leading cause of hospital and community acquired infections globally. Methicillin-resistant Staphylococcus aureus (MRSA) prevalence has been reported to be high in various settings and is associated with increased morbidity, mortality and risk of nosocomial outbreaks. Surveillance of prevalence and antibiotic susceptibility patterns is important to ensure appropriate antibiotic prescription. The objective of our study was to establish the prevalence of S. aureus, to identify patterns of susceptibility to commonly used antibiotics and quantify contemporary penicillin resistance among S. aureus. A retrospective study was conducted at the Mater Misericordiae Hospital, Nairobi. The study involved a review of non-duplicate records of specimens analyzed between January 2014 and December 2018.A specimen was categorized as Penicillin susceptible (PSSA) if susceptible to Penicillin and Oxacillin, MSSA if resistant to Penicillin but susceptible to Oxacillin, and MRSA if resistant to Oxacillin. We present proportions of S. aureus that was PSSA, MSSA and MRSA. Multivariate logistic regression was used to determine the association between the presence of S. aureus isolates and the source of the clinical specimen (in vs. outpatient), age and gender. A total of 659 specimens of S. aureus were analyzed in the 5-year period. ​​PSSA was the most prevalent organism seen (60.85%) while MRSA was the least prevalent (0.61 %). Most S. aureus was isolated in pus from wound swabs-644 (73. 3%). A significant increase in susceptibility of S. aureus to Penicillin and Amoxicillin-clavulanic acid was observed during the study period however, sensitivity to Amoxicillin declined. This study demonstrated a high prevalence of Penicillin Sensitive S. aureus and a low prevalence of MRSA.