In vitro mecA gene transfer among Staphylococcus aureus in Malaysian clinical isolates

Abstract

A simple experiment was performed to observe in vitro transfer of mecA gene from methicillin-resistant Staphylococcus aureus, Malaysian clinical isolates, to methicillin-sensitive one. PCR-based method was used in combination with the selective antibiotic screening method to study the transfer of resistance among clinical isolates carrying different genetic markers. After performing the mixed liquid culture experiments, two types of the transconjugants were obtained. Transconjugants were analyzed by PCR for the presence of mecA and ccr recombinase genes. The mecA, ccrA3 and ccrB2 genes were detected in donor strains as well as in both types of transconjugants. Transfer of mecA, ccrA3 and ccrB2 genes from donor to recipient strains that were present in close proximity during in vitro experiment may suggest possibility of horizontal gene transfer (HGT) among S. aureus clinical strains. Bacterial co-infections in vivo where the bacteria could be in close proximity are likely to be a possible point of horizontal gene transfer (HGT) with regard to certain antibiotic resistant genes.

Key words: MecA, horizontal gene transfer, SCCmec, ccr genes, methicillin-resistant Staphylococcus aureus (MRSA).