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Chlorhexidine MICs Remain Stable Among Antibiotic-Resistant Bacterial Isolates Collected from 2005 to 2019 at Three US Sites

Published online by Cambridge University Press:  02 November 2020

Joseph Lutgring
Affiliation:
Centers for Disease Control and Prevention
Julian Grass
Affiliation:
Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention
David Lonsway
Affiliation:
Centers for Disease Control and Prevention
Brian Yoo
Affiliation:
Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention
Erin Epson
Affiliation:
California Department of Public Health, Healthcare-Associated Infections Program
Megan Crumpler
Affiliation:
Orange County Health Care Agency
Karen Galliher
Affiliation:
Orange County Health Care Agency Kathleen California Department of Public Health
Matthew Zahn
Affiliation:
Orange County Health Care Agency
Eric Evans
Affiliation:
Emory University, Rollins School of Public Health
Jesse Jacob
Affiliation:
Emory University
Alexander Page
Affiliation:
Georgia Emerging Infections Program
Sarah Satola
Affiliation:
Emory University School of Medicine
Gillian Smith
Affiliation:
Georgia Emerging Infections Program
Marion Kainer
Affiliation:
Western Health
Mary Hayden
Affiliation:
Rush University Medical Center
Sujan Reddy
Affiliation:
Centers for Disease Control and Prevention
Christopher Elkins
Affiliation:
Centers for Disease Control and Prevention
Shelley Magill
Affiliation:
Centers for Disease Control and Prevention
Alice Guh
Affiliation:
Centers for Disease Control and Prevention
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Abstract

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Background: Chlorhexidine bathing reduces bacterial skin colonization and prevents infections in specific patient populations. As chlorhexidine use becomes more widespread, concerns about bacterial tolerance to chlorhexidine have increased; however, testing for chlorhexidine minimum inhibitory concentrations (MICs) is challenging. We adapted a broth microdilution (BMD) method to determine whether chlorhexidine MICs changed over time among 4 important healthcare-associated pathogens. Methods: Antibiotic-resistant bacterial isolates (Staphylococcus aureus from 2005 to 2019 and Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae complex from 2011 to 2019) were collected through Emerging Infections Program surveillance in 2 sites (Georgia and Tennessee) or through public health reporting in 1 site (Orange County, California). A convenience sample of isolates were collected from facilities with varying amounts of chlorhexidine use. We performed BMD testing using laboratory-developed panels with chlorhexidine digluconate concentrations ranging from 0.125 to 64 μg/mL. After successfully establishing reproducibility with quality control organisms, 3 laboratories performed MIC testing. For each organism, epidemiological cutoff values (ECVs) were established using ECOFFinder. Results: Among 538 isolates tested (129 S. aureus, 158 E. coli, 142 K. pneumoniae, and 109 E. cloacae complex), S. aureus, E. coli, K. pneumoniae, and E. cloacae complex ECVs were 8, 4, 64, and 64 µg/mL, respectively (Table 1). Moreover, 14 isolates had an MIC above the ECV (12 E. coli and 2 E. cloacae complex). The MIC50 of each species is reported over time (Table 2). Conclusions: Using an adapted BMD method, we found that chlorhexidine MICs did not increase over time among a limited sample of S. aureus, E. coli, K. pneumoniae, and E. cloacae complex isolates. Although these results are reassuring, continued surveillance for elevated chlorhexidine MICs in isolates from patients with well-characterized chlorhexidine exposure is needed as chlorhexidine use increases.

Funding: None

Disclosures: None

Type
Oral Presentations
Copyright
© 2020 by The Society for Healthcare Epidemiology of America. All rights reserved.