RESISTANCE TO METHICILLIN AND OTHER ANTIBIOTICS IN ISOLATES OF STAPHYLOCOCCUS-AUREUS FROM BLOOD AND CEREBROSPINAL-FLUID, ENGLAND AND WALES,1989-95

Background Methicillin-resistant Staphylococcus aureus (MRSA) strains are colonising hospital patients in most areas of England and Wales, U K. The extent to which they cause invasive infection can be gauged fro m their presence in isolates from blood or cerebrospinal fluid. Method s About 200 clinical laboratories reported the results of susceptibili ty testing of between 4501 and 6370 isolates of S aureus from blood or cerebrospinal fluid in each of the years 1989-95. We assessed the rat e of resistance to methicillin and other antibiotics for each of these years. Findings Resistance to methicillin was stable at about 1.5% of isolates during 1989-91, but increased thereafter to 13.2% in 1995 (p <0.001). At the same time there was a significant increase in the perc entage of isolates resistant to erythromycin, clindamycin, ciprofloxac in, gentamicin, trimethoprim, and rifampicin (p<0.001 for each)-resist ance characteristics often seen in MRSA. Resistance to benzylpenicilli n increased slightly but significantly (p>0.001); resistance to fusidi c acid was stable (p>0.05); resistance to tetracycline decreased signi ficantly (P<0.001). Interpretation Among cases of S aureus bacteraemia , the proportion due to MRSA has increased significantly. Bacteraemia due to MRSA has a poor prognosis, especially if not treated with suita ble antibiotics. Therefore, these findings are important, especially f or management of patients and the development of antibiotic policies.