Evolution of multiple drug resistance in staphylococci

Since the dawn of the era of antibiotic therapy, beginning with the introduction of the first penicillins (ßlactams) in the 1940s, strains of Staphylococcus aureus exhibiting resistance to antibiotics have become more and more prevalent in both clinical and community settings. Foremost among these strains are the so-called methicillin-resistant S. aureus (MRSA), which have gained worldwide notoriety as hospital ‘superbugs’. The name MRSA belies the true nature of these organisms, as they are not only resistant to penicillin and the ß-lactamaseresistant penicillins, such as methicillin, oxacillin and flucloxacillin, but are usually also resistant to a significant array of other antibiotics (Table 1), representing most of the available drug classes.