A survey of attitudes towards methicillin-resistant Staphylococcus aureus bacteraemias amongst United Kingdom microbiologists

Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSIs) in the UK are common and associated with significant morbidity and mortality. Vancomycin is the usual first-line therapy. However, vancomycin treatment of BSIs due to MRSA strains with vancomycin MICs of 1-2 mg/L is successful in <10% of cases. No consensus exists on when to use newer agents, particularly when vancomycin MICs are >1 mg/L. We therefore surveyed UK practices of the management of MRSA BSIs due to isolates with increased vancomycin MICs. Methods: Five hundred and seventy-one UK consultant microbiologists were contacted via e-mail and asked to take part in an online survey, hosted at www.surveymonkey.com. Responses were collated by the website, downloaded and analysed in a Microsoft® Excel (Microsoft Corporation) spreadsheet. Results: One hundred and eight respondents participated in the survey. Only 32.7% routinely measure MICs, mostly by Etest. Forty-two percent use vancomycin alone for removable-focus infections, whilst for infections of cardiac or orthopaedic origin, 49% would add rifampicin. Few respondents use daptomycin, linezolid or tigecycline empirically. Sixty-nine percent would use linezolid as a second-line agent, with only 19% opting for daptomycin. For an isolate with a vancomycin MIC of 4 mg/L, respondents would use daptomycin (81%) or linezolid (91%) in patients with a poor clinical response. Conclusions: Vancomycin is the mainstay therapy for MRSA BSIs, even when MICs are not measured or raised, despite evidence of high failure rates. The use of newer agents frequently does not follow European or US licensed indications, may be inappropriate and may result in avoidable deaths.