1963. Mupirocin Resistance and Chlorhexidine (CHG) Non-Susceptibility in a Large Multi-Center Sample of Methicillin-Resistant Staphylococcus aureus (MRSA) and Gram-Negative Rod (GNR) Isolates
Session: Oral Abstract Session: Controlling Resistant Gram Positive Infections
Saturday, October 10, 2015: 3:00 PM
Room: 5--AB

Background: As use of nasal and body decolonization increases, there are periodic reports of mupirocin resistance and CHG non-susceptibility. A large multi-state sample of MRSA and GNR isolates was tested to assess the frequency of non-susceptibility to these agents.  

Methods: We studied MRSA and select GNR isolates identified in routine clinical cultures from non-critically ill patients on study units in 53 community hospitals served by 41 laboratories in 15 states. Isolate were collected from March - November 2013, during the baseline period of a large multicenter trial of decolonization in participating HCA-affiliated hospitals. Mupirocin susceptibility was determined by Etest. Low-level mupirocin resistance (LLMR) was defined as a minimum inhibitory concentration (MIC) of mupirocin between 8-64 µg/ml and high-level mupirocin resistance (HLMR) as MIC >256 µg/ml. CHG susceptibility was determined by microtiter dilution. An epidemiologic cut-off approach was used to estimate non-susceptibility to CHG, based on published data and observed results. Breakpoints for CHG non-susceptibility were species-specific: MIC >4 µg/ml for MRSA and Escherichia coli; >16 µg/ml for Serratia marcescens; >32 µg/ml for Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter baumannii; >64 µg/ml for Klebsiella spp.; and >256 µg/ml for Proteus mirabilis.

Results: 4263 isolates (2120 MRSA and 2143 GNR) were collected (facility range 15 - 161). Common GNR isolates were E. coli (48%), Klebsiella pneumoniae (19%), P. aeruginosa (16%), and P. mirabilis (9%).

Six percent (95% CI, 5-7%) of MRSA expressed LLMR and 11% (95% CI, 10-13%) expressed HLMR. Highest percentage LLMR was found in the Midwest (9%) and lowest percentage in the West (3%).  Highest percentage HLMR was found in the Southeast (14%) and lowest percentage in the West (7%). CHG non-susceptibility was found in 0% of MRSA and 2.7% (95% CI, 2.0-3.3%) of GNR: 17 (2%) E. coli, 6 (1%) Klebsiella spp, 17 (35%) S. marcescens, 13 (4%) P. aeruginosa and 5 (14%) S. maltophilia (Figure).

Conclusion: Mupirocin resistance in this cohort of community hospitals varied across U.S. regions, with HLMR resistance exceeding 10% in some areas. CHG non-susceptibility was negligible in MRSA and uncommon in most GNR species.

 

Katherine Haffenreffer, BS1, Lena M Portillo, BS, MT(ASCP)2, Taliser Avery, MS1, Rebecca E. Kaganov, BA1, Lauren Shimelman, BA1, Michael V. Murphy, BA1, Julia Moody, MS3, Christopher Bushe, MSHA, MT(ASCP)3, Edward Septimus, MD, FIDSA, FSHEA3,4, Robert a. Weinstein, MD, FIDSA, FSHEA5,6, Jason Hickok, RN, MBA3, Jonathan Perlin, MD, PhD, MSHA, FACP, FACMI3, Susan S. Huang, MD, MPH, FIDSA, FSHEA7 and Mary K. Hayden, MD, FIDSA, FSHEA8, (1)Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, (2)College of American Pathologists, Northfield, IL, (3)Clinical Services Group, HCA Inc., Nashville, TN, (4)Texas A&M Health Science Center College of Medicine, Houston, TX, (5)Cook County Health & Hospitals System, Chicago, IL, (6)Rush Medical College, Chicago, IL, (7)Division of Infectious Diseases and Health Policy Research Institute, University of California Irvine School of Medicine, Irvine, CA, (8)Internal Medicine (Infectious Diseases) and Pathology, Rush University Medical Center, Chicago, IL

Disclosures:

K. Haffenreffer, Sage Inc.: Investigative Team Member , Contributed product for ABATE Study
Molnlycke: Investigative Team Member , Contributed product for ABATE Study

L. M. Portillo, Sage Inc.: Investigative Team Member , Contributed product for ABATE Study
Molnlycke: Investigative Team Member , Contributed product for ABATE Study

T. Avery, Sage Inc.: Investigative Team Member , Contributed product for ABATE Study
Molnlycke: Investigative Team Member , Contributed product for ABATE Study

R. E. Kaganov, Sage Inc.: Investigative Team Member , Contributed product for ABATE Study
Molnlycke: Investigative Team Member , Contributed product for ABATE Study

L. Shimelman, Sage Inc.: Investigative Team Member , Contributed product for ABATE Study
Molnlycke: Investigative Team Member , Contributed product for ABATE Study

M. V. Murphy, Sage Inc.: Investigative Team Member , Contributed product for ABATE Study
Molnlycke: Investigative Team Member , Contributed product for ABATE Study

J. Moody, Sage Inc.: Investigator , Contributed product for ABATE Study
Molnlycke: Investigator , Contributed product for ABATE Study

C. Bushe, Sage Inc.: Investigator , Contributed product for ABATE Study
Molnlycke: Investigator , Contributed product for ABATE Study

E. Septimus, Sage Inc.: Investigator , Contributed product for ABATE Study
Molnlycke: Investigator , Contributed product for ABATE Study

R. A. Weinstein, Sage Inc.: Investigator , Contributed product for ABATE Study
Molnlycke: Investigator , Contributed product for ABATE Study

J. Hickok, Sage Inc.: Investigator , Contributed product for ABATE Study
Molnlycke: Investigator , Contributed product for ABATE Study

J. Perlin, Sage Inc.: Investigator , Contributed product for ABATE Study
Molnlycke: Investigator , Contributed product for ABATE Study

S. S. Huang, Sage Inc.: Investigator , Contributed product for ABATE Study
Molnlycke: Investigator , Contributed product for ABATE Study
3M: Investigator , Conducting studies in which participating healthcare facilities are receiving product from 3M.

M. K. Hayden, Sage Products, Inc.: Sage provided CHG product at no cost to a study on which I was PI, and on another study on which I am CoI. , Sage provided CHG product at no cost to a study on which I was PI, and on another study on which I am CoI.
Molnlycke: Molnlycke provided CHG product at no charge to facilities participating in a research project on which I am a co-investigator. , Molnlycke provided CHG product at no charge to facilities participating in a research project on which I am a co-investigator.

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