Methicillin-resistant Staphylococcus aureus in England and Wales.
Methicillin-resistant Staphylococcus aureus (MRSA) were detected soon after the introduction of methicillin in 1960, and reports of their isolation increased up to 1971. Changes in antibiotic usage were associated with a fall and then, in the early 1980s, a further rise in the number of reports. This article reviews the various surveys that have been conducted to establish the frequency, distribution and strain varieties of MRSA. The first strain to be recognised as epidemic (ie, affecting more than one hospital), was defined by phage typing and antibiogram, confirmed with molecular typing, and designated EMRSA-1. It was first detected in 1981 and became progressively more widespread until it began to decline in 1987. Only three health regions reported this strain in the first quarter of 1991. EMRSA-2 has remained restricted to the South East and South West Thames regions. EMRSA-3 appeared in the South East Thames region in 1987 and has since spread, being reported from eight health regions in the first quarter of 1991. At least 11 other strains of MRSA affecting more than one hospital have been detected and ten endemic strains (restricted to single hospitals) have been identified. Imported strains of MRSA, often introduced following the repatriation of road traffic accident victims, may include strains with epidemic potential and local spread has followed importation in at least two incidents. Continued surveillance of epidemic MRSA strains and the search for simple and widely applicable markers, such as unusual antibiotic resistance patterns or biochemical features, are needed for the prompt application of control measures.