Cystic fibrosis (CF) is an inherited recessive disease that affects mucocillary clearance in the lung,
allowing it to be colonised with bacteria such as Staphylococcus aureus. To survive in the CF lung S.
aureus adapts both phenotypically and genotypically, through various mechanisms. In this study,
multiple specimens were collected from the participants and were processed routinely and were
additionally cultured in chromogenic media. Multiplex PCR assays were employed to detect methicillin
resistance and selected virulence and quaternary ammonium compound (qac) genes. Genetic
relatedness of the S. aureus was determined using agr, SCCmec and spa typing as well as pulsed field
gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Thirty-three S. aureus isolates
were isolated, of which 51% (17/33) were methicillin resistant S. aureus (MRSA). The virulence and
qac genes were more prevalent in MRSA than the methicillin sensitive S. aureus (MSSA) isolates. The
PFGE analysis showed nine distinct pulsotypes while MLST showed eight sequence types. All the STs
detected in this study, except for ST508 have been previously isolated from CF patients according to
the literature. This study showed a genetically diverse S. aureus population with a high prevalence of
virulence genes among the MRSA isolates from the CF clinic.