MOBILE ELEMENTS IN THE EVOLUTION AND SPREAD OF A MULTIPLE-DRUG RESISTANCE IN STAPHYLOCOCCI

Since the introduction of antimicrobial chemotherapy, staphylococci ha ve shown a remarkable propensity to develop drug resistance. As a resu lt, strains have evolved that are resistant to most classes of clinica lly useful antimicrobial agents. The emergence of these multiply-drug- resistant strains is primarily due to the capture of pre-existent resi stance genes. In combination with plasmids and gene transfer mechanism s, mobile genetic elements have been central to the acquisition and di ssemination of this resistance. In particular they have played a signi ficant role in the assembly of drug-resistance gene clusters in these multiply-resistant staphylococci.