Chlorhexidine washing in intensive care does not reduce bloodstream infections, blood culture contamination and drug-resistant microorganism acquisition: an interrupted time series analysis

Abstract

Background: Health care-associated infections are a major cause of morbidity and mortality in intensive care patients. The effect of daily washing with chlorhexidine on these infections is controversial. Methods: Single-centre, retrospective, open-label, sequential period, interrupted time series (ITS) analysis in a 31-bed tertiary referral mixed intensive care unit (ICU), comparing daily washing with water and soap (from January 2011 to August 2013) with chlorhexidine washing (from November 2013 to December 2015), after the introduction of a unit-level policy of chlorhexidine washing. All patients in the ICU were included in the study, except: if they were under 18 years of age, if their ICU stay was less than 24 hours (to ensure that all studied patients had at least one exposure to the daily wash intervention), or if patients had a known allergy to chlorhexidine. Outcome measures included: clinically significant positive blood cultures attributable to the ICU stay; contaminated blood cultures; newly acquired multidrug-resistant microorganisms (MDRO) such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus (VRE) or multidrug-resistant gram-negative (MRGN) isolates attributable to ICU from clinical and screening cultures; and newly acquired Clostridium difficile infections (CDIs). Incidence rates of these outcomes were calculated per 1000 patient days. MDRO acquisition rates were corrected for background hospital period prevalence rates of MDRO. Results: A total of 6634 patients were included in the study. ITS analysis showed no significant level or slope changes in any of the outcome measures after implementation of chlorhexidine washing. The incidence rate of clinically significant positive blood cultures during the chlorhexidine period compared with the water and soap period was 3.6 v 4.7 (P = 0.37); blood culture contamination rates were 11.8 v 9.5 (P = 0.56); incidence rates of new ICU-associated MDRO acquisitions were 3.22 v 3.69 (P = 0.27); incidence rates of new CDI were 2.01 v 0.79 (P = 0.16). Outcomes after adjustment for known and potential confounders were similar. Conclusions: In this real-world, long term ICU study, implementation of a unit-level policy of daily washing with chlorhexidine impregnated cloths was not associated with a reduction in the rates of ICUassociated clinically significant positive blood cultures, blood culture contamination, newly acquired MDRO isolates, and CDIs.