Abstract
Background: Methicillin-resistant Staphylococcus aureus (MRSA) are a major cause of hospital- and community-acquired infection. They can colonize humans and cause a wide range of infections including pneumonia, endocarditis and bacteraemia. We investigated the molecular mechanism of resistance and virulence of MRSA isolates from a teaching hospital in Ghana. Methodology: A total of 91 S. aureus isolates constituted the initial bacterial sample. Identification of S. aureus was confirmed by the VITEK 2 system. The cefoxitin screen test was used to detect MRSA and antibiotic susceptibility was determined using the VITEK 2 system. The resistance ( mecA , blaZ , aac-aph , ermC , and tetK ) and virulence ( lukS/F-PV , hla , hld and eta ) genes were amplified by polymerase chain reaction (PCR) and positive samples subjected to DNA sequencing. Pulsed field gel electrophoresis (PFGE) was used to ascertain the relatedness of the isolates. Results: Fifty-eight of 91 (63.7%) isolates were putatively methicillin resistant by the phenotypic cefoxitin screen test and oxacillin MICs. However, 43 (47%) of the isolates were genotypically confirmed as MRSA based on PCR detection of the mecA gene. Furthermore, 37.9% of isolates displayed resistance to tetracycline, 19% to trimethoprim-sulphamethoxazole, 15.5% to clindamycin, 12.1% to gentamicin, 13.8% to ciprofloxacin and erythromycin, 6.9% to moxifloxacin and 7.0% to rifampicin. None of the isolates was positive for inducible clindamycin resistance. The prevalence of resistance ( mecA , blaZ , aac(6’)-aph(2’’) , tetK , and ermC ) and virulence ( hla and lukS/F-PV ) genes respectively were 74%, 33%, 22%, 19%, 3%, 5% and 3%, with isolates organized in two highly related clades. Conclusion: Results indicate a fairly high occurrence of MRSA, which can complicate the effective therapy of S. aureus infections, necessitating surveillance and stringent infection control programmes to forestall its spread. Keywords: MRSA, mecA, blaZ, hla, lukS/F-PV
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More From: African Journal of Clinical and Experimental Microbiology
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