ABSTRACT: BACKGROUND:The hospital environment is a source of pathogen transmission. The effect of enhanced disinfection strategies on the hospital-wide incidence of infection has not been investigated in a multicentre, randomised controlled trial. We aimed to assess the effectiveness of four disinfection strategies on hospital-wide incidence of multidrug-resistant organisms and Clostridium difficile in the Benefits of Enhanced Terminal Room (BETR) Disinfection study. METHODS:We did a prespecified secondary analysis of the results from the BETR Disinfection study, a pragmatic, multicentre, crossover cluster-randomised trial that assessed four different strategies for terminal room disinfection in nine hospitals in the southeastern USA. Rooms from which a patient with a specific infection or colonisation (due to the target organisms C difficile, meticillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci (VRE), or multidrug-resistant Acinetobacter spp) was discharged were terminally disinfected with one of four strategies: standard disinfection (quaternary ammonium disinfectant, except for C difficile, for which 10% hypochlorite [bleach] was used; reference); standard disinfection and disinfecting ultraviolet light (UV-C), except for C difficile, for which bleach and UV-C was used (UV strategy); 10% hypochlorite (bleach strategy); and bleach and UV-C (bleach and UV strategy). We randomly assigned the sequence of strategies for each hospital (1:1:1:1), and each strategy was used for 7 months, including a 1-month wash-in period and 6 months of data collection. The prespecified secondary outcomes were hospital-wide, hospital-acquired incidence of all target organisms (calculated as number of patients with hospital-acquired infection with a target organism per 10?000 patient days), and hospital-wide, hospital-acquired incidence of each target organism separately. BETR Disinfection is registered with ClinicalTrials.gov, number NCT01579370. FINDINGS:Between April, 2012, and July, 2014, there were 271?740 unique patients with 375?918 admissions. 314?610 admissions met all inclusion criteria (n=73?071 in the reference study period, n=81?621 in the UV study period, n=78?760 in the bleach study period, and n=81?158 in the bleach and UV study period). 2681 incidenct cases of hospital-acquired infection or colonisation occurred during the study. There was no significant difference in the hospital-wide risk of target organism acquisition between standard disinfection and the three enhanced terminal disinfection strategies for all target multidrug-resistant organisms (UV study period relative risk [RR] 0·89, 95% CI 0·79-1·00; p=0·052; bleach study period 0·92, 0·79-1·08; p=0·32; bleach and UV study period 0·99, 0·89-1·11; p=0·89). The decrease in risk in the UV study period was driven by decreases in risk of acquisition of C difficile (RR 0·89, 95% CI 0·80-0·99; p=0·031) and VRE (0·56, 0·31-0·996; p=0·048). INTERPRETATION:Enhanced terminal room disinfection with UV in a targeted subset of high-risk rooms led to a decrease in hospital-wide incidence of C difficile and VRE. Enhanced disinfection overcomes limitations of standard disinfection strategies and is a potential strategy to reduce the risk of acquisition of multidrug-resistant organisms and C difficile. FUNDING:US Centers for Disease Control and Prevention.