New threats to the control of methicillin-resistant Staphylococcus aureus.

Several countries have achieved considerable success in the control of epidemic methicillin-resistant Staphylococcus aureus (MRSA). However, in several hospitals in the UK, MRSA strains of enhanced epidemicity, notably EMRSA-16, are becoming endemic. Our inability to eliminate the cause of a single-strain outbreak is unfamiliar and unnerving. Factors in 'market-led' health care delivery that hinder control of MRSA include a shortage of inpatient beds, patients moving from ward to ward, and more mixed-specialty wards. Increasing use of day treatments leaves an inpatient hospital population with more risk factors for infection. Early discharge of infected patients to convalescent homes, or to homes for the elderly, has created a new reservoir of infected and colonized patients. The emergence of high-level mupirocin resistance may soon also contribute to failure of control. The transfer of vancomycin resistance from Enterococcus faecium to a laboratory strain of S. aureus suggests that, especially in hospitals with both vancomycin-resistant enterococci and MRSA, there is the opportunity for the emergence of vancomycin-resistant MRSA for which there may be no effective antimicrobial prophylaxis or treatment. It is increasingly important to persuade hospital managers that even partial control of MRSA, whilst expensive, is still cost-effective and is a quality issue for individual hospitals. The control of EMRSA-16 in one hospital has recently been estimated to have saved more than 629,000 pounds extra costs. MRSA continues to be at the forefront of those organisms that seriously challenge modern technological medicine and surgery.