Screening and isolation for infection control.

Control measures aimed to reduce the prevalence of healthcare-associated infections include active surveillance cultures (ASCs), contact isolation of patients colonised with epidemiologically significant pathogens, and pre-emptive isolation of high risk patients. However, the benefits of these measures are questionable. A systematic review of isolation policies demonstrated that intensive concerted interventions including isolation can substantially reduce nosocomial meticillin-resistant Staphylococcus aureus (MRSA) infection. Monitoring of interventions is fundamental. Surveillance data should be presented and fed back appropriately. International guidelines suggest that only intensive care units should apply extensive ASCs. However, legislation for mandatory screening at hospital admission has been advocated in many countries. Targeted screening could be used to limit the potential for dissemination of antibiotic-resistant pathogens from otherwise unsuspected carriers from the start of patients' hospitalisation, as opposed to other strategies, in which screening programmes target patients already hospitalised. Although the influx of antibiotic-resistant pathogens into the hospital would not change, early detection would reduce the time colonised patients might have to disseminate pathogens. Recently, rapid methods for molecular detection of MRSA have been developed. Data on the impact of these tests on the MRSA acquisition rate are extremely heterogeneous. Published studies differ according to the settings in which they have been evaluated, the choice of patient population to be screened, other infection control measures employed and, most importantly, study design and baseline prevalence of MRSA. Based on these studies, definitive recommendations cannot be made.