We aimed to establish whether screening for methicillin-resistant Staphylococcus aureus (MRSA) and body decontamination upon admission to an Intensive Care Unit (ICU), in combination with barrier precautions, reduced rates of MRSA infection acquired on the unit. This was an interrupted time series study employing segmented regression analysis of data collected for all patients admitted to a 16-bed adult ICU over 48 months. Before the intervention (24 months; 1232 patients (44% female)), MRSA was sought from clinical cultures only and positive patients were barrier nursed in isolation. During the intervention (24 months; 1421 patients (54% female)), all ICU patients were screened for MRSA on admission and were barrier nursed in single rooms when established as MRSA-positive; all were given topical nasal anti-MRSA preparations and daily bed baths with 4% chlorhexidine throughout their stay. Changes in the proportion of patients colonised or infected with MRSA in the ICU were assessed. Before the intervention, 193 new MRSA cases (16%) were identified from 1232 ICU admissions; during the intervention, this was reduced to 92 cases (6%) of 1421 admissions. By time series regression analysis, the proportion of patients with MRSA decreased by 11.38% from ca. 15% to ca. 5% (ca. three-fold reduction) (95% confidence interval 3.5-19.3%; P=0.005). Thus, treatment of 11 patients prevented I clinical case of MRSA. Mean length of stay decreased significantly (P < 0.001). Although MRSA and methicillin-susceptible S. aureus bacteraemia rates dropped, the changes detected were not statistically significant. The proportion of patients with coagulase-negative staphylococcal bacteraemia decreased significantly (P < 0.001) and the trend changed from increasing to decreasing (P < 0.001), as did the trend in glycopeptide use (P=0.014). An inexpensive and easy to implement intervention to control MRSA in the ICU was highly successful without compromising antimicrobial susceptibility. (C) 2007 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.