Abstract:
S. aureus, particularly methicillin-resistant S. aureus (MRSA) remains an important pathogen,
but little is known about its circulation among student populations in Kenya. This study was
conducted to determine the prevalence, antimicrobial susceptibility profiles, the carriage and
diversity of mecA cassettes and lukFS-PV genes among the S. aureus isolates and factors for
colonization by S. aureus and MRSA. To achieve these, S. aureus isolates were recovered from
nasal, phone and pen swabs. Antimicrobial susceptibility tests were done on all S. aureus
isolates. All the S. aureus isolates were screened for presence of mecA gene, SCCmec elements,
while a sample of the isolates was screened for presence lukFS-PV genes on their gene cassettes
using conventional PCR methods. A sample consisting of 44 isolates of the S. aureus were also
analyzed for genetic relatedness via conventional PCR methods. A total of 231 S. aureus
isolates were recovered from 89 (37.6%) participants out of 237 participants. All S. aureus
isolates were susceptible to nitrofurantoin and linezolid and 194 (84%) isolates were resistant to
ampicillin. Resistances to amoxicillin, erythromycin, chloramphenicol, gentamicin,
ciprofloxacin, norfloxacin and trimethoprim-sulfamethoxazole were below 20%. The MRSA
prevalence was 11.3% (26/231). The mecA gene was present in 17 (65.4%) of the MRSA
strains. The SCCmecV was the most prevalent, 16 (61.5%), among the MRSA. Carriage of
lukFS-PV gene was 31.5% and 26.9% among the MRSA and MSSA strains respectively. The
factors for MRSA colonization, the factors were staying in Halls E, C and B (p=0.03) and
failure to disinfect phones and pens (p=0.02). Therefore, the study confirmed the circulation of
MRSA among a health study student population, thus necessitating a continued surveillance to
monitor circulation of MRSA among healthy students.
