290. Susceptibility of Nosocomial Staphylococcus aureus to Chlorhexidine After Implementation of a Hospital-wide Antiseptic Bathing Regimen
Session: Poster Abstract Session: HAI: MSSA, MRSA, and other Gram-Positives
Thursday, October 27, 2016
Room: Poster Hall
Background: Bathing hospitalized patients with chlorhexidine gluconate is an effective way to reduce healthcare-associated infections by multi-drug-resistant organisms such as MRSA. There is concern that widespread use of chlorhexidine (CHX) will promote the emergence of bacterial resistance. This study assessed CHX susceptibility of bloodstream-infecting S aureus from 4 distinct time periods with well-characterized usage of CHX patient bathing.
Methods: 104 freezer-banked S aureus bloodstream isolates, recovered from patients hospitalized for greater than 72 hours, were selected for analysis. Four time periods were studied: (A) pre-CHX patient bathing (before 2009); (B) widespread use of CHX bathing during an institution-wide study (Feb 2009-Aug 2010); (C) washout period with no use of CHX bathing (Sep 2010-Sep 2011); and (D) reintroduction of institution-wide CHX patient bathing (Oct 2011-May 2015). CHX susceptibility was determined by broth microdilution. The Kruskal-Wallis test was used to compare the distribution of MIC between periods; the Mann-Whitney test with Bonferroni adjustment was used for pairwise comparisons between time periods. Isolates were also screened via PCR for the presence of qacA/B efflux pump-encoding genes known to mediate reduced susceptibility to CHX in S aureus.
Results: Table 1 shows the number and percentage of isolates per MIC breakpoint. The mean MIC was significantly higher prior to widespread institutional use of CHX bathing compared to the other time periods (p=0.0081): mean MIC + SD (µg/ml CHX): 0.97 + 0.46, 0.75 + 0.57, 0.72 + 0.26, 0.69 + 0.25 for time periods A-D, respectively (A vs B, p=0.048, A vs D, p=0.024). Furthermore, no isolates were found to harbor qacA/Bresistance genes.
Conclusion: Use of an institution-wide CHX patient bathing program for several years has not been associated with decreased susceptibility of Staphylococcus aureus to the antiseptic. These findings support continued use of CHX as a safe and efficacious means of reducing nosocomial infections.
Cole Marolf, Medical Student1, Paul D. Fey, PhD2, Roxanne Alter, MS1, Elizabeth Lyden, MS3 and Mark E. Rupp, MD, FIDSA, FSHEA4, (1)University of Nebraska Medical Center, Omaha, NE, (2)Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, (3)Epidemiology, University of Nebraska Medical Center, Omaha, NE, (4)Division of Infectious Diseases, University of Nebraska Medical Center, Omaha, NE
P. D. Fey,