Methicillin resistance in Staphylococcus aureus

There is controversy regarding methods employed for the detection of methicillin resistance in Staphylococcus aureus, and dispute whether infections caused by these organisms can be successfully treated with methicillin or similar antibiotic agents. Cell populations of methicillin-resistant Staph, aureus (MRSA) are heterogeneous with respect to the level of resistance expressed, but always contain a subpopulation of highly resistant cells which can neither be inhibited nor killed by beta-lactam antibiotic agents. Clinical experience confirms that in severe infections, particularly when host defences are impaired, the use of beta-lactam antibiotic agents to treat MRSA is associated with an unacceptably high failure rate. Current Victorian strains of MRSA are multiresistant. Thus vancomycin is the drug of choice for life- threatening infections, while the combination of fusidic acid either with flucloxacillin or with rifampicin is useful for infections of moderate severity.