Infection Control & Hospital Epidemiology (2018), 39, 1257–1261 doi:10.1017/ice.2018.182
Concise Communication
Comparison of nylon-flocked swab and cellulose sponge methods for carbapenem-resistant Enterobacteriaceae and gram-negative organism recovery from high-touch surfaces in patient rooms
Clare Rock MD, MS1,2,3, Michael Anderson BS1, Shawna Lewis BA1, Verna Scheeler MLA1, Elaine Nowakowski3, Yea-Jen Hsu PhD, MHA4, Aaron M. Milstone MD, MHS1,2,3, Karen C. Carroll MD1, Lisa L. Maragakis MD, MPH1,2,3
and Patricia J. Simner PhD, D(ABMM)1 for the CDC Prevention Epicenters Program 1Johns Hopkins University School of Medicine, Baltimore, Maryland, 2Johns Hopkins Medicine Armstrong Institute for Patient Safety and Quality, Baltimore, Maryland, 3Department of Hospital Epidemiology and Infection Control, The Johns Hopkins Hospital, Baltimore, Maryland and 4Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
Abstract
The ideal sampling method and benefit of qualitative versus quantitative culture for carbapenem-resistant Enterobacteriaceae (CRE) recovery in hospitalized patient rooms and bathrooms is unknown. Although the use of nylon-flocked swabs improved overall gram- negative organism recovery compared with cellulose sponges, they were similar for CRE recovery. Quantitative culture was inferior and unrevealing beyond the qualitative results.
(Received 30 April 2018; accepted 2 July 2018; electronically published August 28, 2018)
Carbapenem-resistant Enterobacteriaceae (CRE) are important healthcare-associated pathogens with high mortality rates.1,2 CRE recovery from the patient environment may be informative for the evaluation of efficiency of cleaning and disinfection in routine and outbreak settings as well as infection prevention research studies.3 Although the rayon-tipped swab method has better sensitivity than the cellulose sponge (CS) method for detecting Acinetobacter in the near-patient environment, the ideal sampling method for CRE detection from high-touch surfaces (HTSs) in the patient room is unknown.4 We compared 2 sampling methods (nylon-flocked swab [NFS] and CS) and 2 culturing methods (qualitative and quantitative) for the detection of CRE, non-CRE carbapenem-resistant organisms, and all other gram-negative organisms in rooms where the occupant harbored CRE.
Methods
At the Johns Hopkins Hospital, a 1,145-bed tertiary-care academic center in Baltimore, Maryland, we prospectively identified patients with recent (past 3 days) clinical or surveillance culture(s) growing CRE who had occupied the same hospital room for the most recent
Author for correspondence: Clare Rock, MD, MS, Johns Hopkins University School
of Medicine, Division of Infectious Diseases, 600 North Wolfe Street, Halsted 831, Baltimore, MD 21287-5425. E-mail:
Clare.Rock@
jhmi.edu. PREVIOUS PRESENTATION: This study was previously presented orally at the
Society for Healthcare Epidemiology of America Spring Conference, Atlanta, Georgia, on May 18-21, 2016.
Cite this article: Rock C, et al. (2008). Comparison of nylon-flocked swab and
cellulose sponge methods for carbapenem-resistant Enterobacteriaceae and gram- negative organism recovery from high-touch surfaces in patient rooms. Infection Control & Hospital Epidemiology 2018, 39, 1257–1261. doi: 10.1017/ice.2018.182
© 2018 by The Society for Healthcare Epidemiology of America. All rights reserved.
2 days. High-touch surfaces (HTSs) from patient rooms were sam- pled. One half of each HTS was sampled using an NFS (eSwab, Copan Diagnostics, Murrieta, CA) dipped in neutralizer buffer (Hardy Diagnostics, Santa Maria, CA) using a previously published method.4,5 An individual NFS was used per half of the HTS. The otherhalfoftheHTSwas sampledusing CS with neutralizer (3M, Maplewood,MN), and up to 5HTSs were sampled with each side of the CS (eg, a composite).4,6 Due to right-hand dominance, bacteria may have been more likely to be removed from that side of the HTS during cleaning. To avoid introducing a systematic bias, alternating sides of the HTS were sampled by each method. For qualitative cultures, PBS with tween broths were held for up to
3 days and subcultured if turbid. For quantitative cultures (including positive and negative controls) CDC protocols were followed, using MacConkey agar for selection of gram-negative organisms, incubated overnightat35°C.5,6 Identification of recovered organisms was performed using matrix-assisted laser desorption ionization time-of- flight mass spectrometry (Bruker Daltonics) and antimicrobial sus- ceptibility testing was performed using the BD Phoenix Automated Microbiology System (Becton Dickinson, Franklin Lakes, NJ).4 Enterobacteriaceae resistant to at least ertapenem were identified as CRE. If a CS was culture positive, then all HTSs of the composite were deemed positive. The limit of detection was determined by preparing a 0.5 McFarland standard, plating 100-µLaliquotsof 10-fold dilution series of Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae ATCC BAA-1705 onto sterile Formica slabs, and by CSand NFSsamplinginasimilar manner to HTS sampling. The frequency of gram-negative organism recovery for each
method was compared to a gold standard, defined as recovery using either the NFS or the CS method. Each HTS was
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