528. Longitudinal Evaluation of Chlorhexidine Resistance Among Multidrug-Resistant Organisms in Relation to Intervention of Daily Chlorhexidine Bathing in Adult Intensive Care Units

Background Chlorhexidine digluconate (CHG), the most widely used antiseptic, has recently been applied to patient washing to decolonize the multidrug-resistant organisms (MDROs), but there are little data on susceptibilities of MDROs to CHG. The purpose of this study was to evaluate CHG resistance among MDROs before and after the intervention of daily CHG bathing in adult intensive care units (ICUs). Methods The intervention of daily body washing with 2% CHG cloths were taken in adult patients the medical or surgical ICU of 23-bed by a crossover manner for 6 months (MICU, July to December 2017; SICU, January to June 2018) in a 1,050-bed, university hospital in the Republic of Korea. Available MDRO isolates were randomly selected from clinical cultures of ICU patients within 6 months before, during and after the intervention, including MRSA, MR-CoNS, VRE, Carbapenem-resistant Pseudomonas aeruginosa (CR-PA), CR-Acinetobacter baumannii (CR-AB). Minimum inhibitory concentrations (MICs) were determined using the broth microdilution method set by the Clinical Laboratory Standards Institute. Determination of the minimum bactericidal concentrations (MBCs) was performed by subculturing 10 µL from each well without visible microbial growth. Cumulative amounts of CHG used in both ICUs was estimated across the study period from January 2008 to June 2018. Results The cumulative CHG consumption from both ICUs increased sharply from 27,503 g to 29,556 g after one-year intervention. The ranges of MICs and MBCs of CHG among MDRO clinical isolates selected by a 6-month phase are summarized in Table 1. Particularly, CR-PA and CR-AB isolates revealed four to eight times higher MICs and MBCs compared with the majority of Gram-positives excepting some VRE isolates. On the other hand, neither MICs and MBCs ranges of CHG from the MDRO isolates nor the monthly incidence of the MDROs from both ICUs were significantly increased before and after the intervention of daily CHG bathing. Conclusion This study indicates that some Gram-negative MDRO isolates with higher MICs and MBCs of CHG might be from longstanding exposure to CHG or efflux pumps. Although 2% daily CHG bathing uses over 1,000 times higher concentrations than the lethal concentration, it might be needed to monitor CHG resistance among MDROs. Disclosures All authors: No reported disclosures.