Colonisation with ESBL-producing and carbapenemase-producing Enterobacteriaceae, vancomycin-resistant enterococci, and meticillin-resistant Staphylococcus aureus in a long-term care facility over one year.

Catherine Ludden,Akke Vellinga,Bernie Austin,James R Johnson,Dearbháile Morris,Martin Cormican

doi:10.1186/s12879-015-0880-5

Abstract

BackgroundThis study examined colonisation with and characteristics of antimicrobial-resistant organisms among residents of a long-term care facility (LTCF) over one year, including strain persistence and molecular diversity among isolates of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae.MethodsSixty-four residents of a LTCF were recruited (51 at baseline, 13 during the year). Data on dependency levels, hospitalisations, and antimicrobial prescribing were collected. Nasal and rectal swabs and catheter urine specimens were examined quarterly, using chromogenic agars, for ESBL-producing Enterobacteriaceae, carbapenemase-producing Enterobacteriaceae (CPE), vancomycin-resistant enterococci (VRE), and meticillin-resistant S. aureus (MRSA). All ESBL-producing E. coli (ESBL-EC) were characterised by pulsed-field gel electrophoresis (PFGE) and PCR to assess for sequence type (ST) ST131, its resistance-associated H30 and H30-Rx subclones, and blaCTX-M,blaTEM,blaSHV, and blaOXA-1.ResultsThe overall number of residents colonised, by organism, was as follows: ESBL-EC, 35 (55%); MRSA, 17 (27%); ESBL-producing K. pneumoniae (ESBL-KP), 5 (8%); VRE, 2 (3%) and CPE, 0 (0%). All 98 ESBL-EC isolates were H30-Rx ST131, with blaCTX-M-group 1. By PFGE, a group of 91 ESBL-EC (from 33 participants) had ≥ 85% similar profiles and resembled UK epidemic strain A/ international pulsotype PFGE812. Sequential ESBL-EC from individual residents were closely related. Six ESBL-KP isolates, from five participants, had blaCTX-M-group 1 and by PFGE were closely related. Colonisation with ESBL and MRSA was associated with location within the LTCF and previous exposure to antimicrobials.ConclusionsAmong LTCF residents, colonisation with ESBL-EC and MRSA was common. All ESBL-EC were H30-Rx ST131, consistent with clonal dissemination.

Highlights

This study examined colonisation with and characteristics of antimicrobial-resistant organisms among residents of a long-term care facility (LTCF) over one year, including strain persistence and molecular diversity among isolates of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae
Spread of CTX-M beta-lactamases is linked with specific epidemic clonal groups such as E. coli sequence type ST131
Participating residents Sixty-four LTCF residents agreed to participate in this study, including 51 (58% of 88 initial residents) at baseline and 13 (45% of 29 subsequently admitted residents) later in the year

Summary

Introduction

This study examined colonisation with and characteristics of antimicrobial-resistant organisms among residents of a long-term care facility (LTCF) over one year, including strain persistence and molecular diversity among isolates of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae. Antimicrobial resistance has been identified as a key public health challenge [1]. Amongst the major acquired antimicrobial-resistant organisms (AROs) are extendedspectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, carbapenemase-producing Enterobacteriaceae (CPE), vancomycin-resistant enterococci (VRE), and meticillin-resistant Staphylococcus aureus (MRSA). ESBL-producing E. coli (ESBL-EC) have become increasingly common throughout the world. Spread of CTX-M beta-lactamases is linked with specific epidemic clonal groups such as E. coli sequence type ST131 (typically of serotype O25b:H4). ST131 has been identified from as early as 1967, ST131 isolates containing ESBLs, predominantly CTX-M-15, emerged mainly in the 2000s [3,4]. There is significant genomic diversity within ST131, with over 170 distinct PFGE patterns/pulsotypes (>94% similar XbaI PFGE profiles) recognised, some of which are associated with particular sources and antimicrobial resistance patterns [3]

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