Inherent colistin resistance in genogroups of the Enterobacter cloacae complex:epidemiological, genetic and biochemical analysis from the BSAC Resistance Surveillance Programme

, BSAC Resistance Surveillance Standing Committee (2020) Inherent colistin resistance in genogroups of the Enterobacter cloacae complex:epidemiological, genetic and biochemical analysis from the BSAC Resistance Surveillance Programme. Journal of Antimicrobial Chemotherapy, 75 (9). 2452–2461. ISSN 0305-7453

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Abstract

BACKGROUND: Polymyxins have re-entered use against problem Gram-negative bacteria. Resistance rates are uncertain, with estimates confounded by selective testing. METHODS: The BSAC Resistance Surveillance Programme has routinely tested colistin since 2010; we reviewed data up to 2017 for relevant Enterobacterales (n = 10 914). Unexpectedly frequent resistance was seen among the Enterobacter cloacae complex isolates (n = 1749); for these, we investigated relationships to species, genome, carbon source utilization and LPS structure. RESULTS: Annual colistin resistance rates among E. cloacae complex isolates were 4.4%-20%, with a rising trend among bloodstream organisms; in contrast, annual rates for Escherichia coli and Klebsiella spp. (including K. aerogenes) generally remained <2%. WGS split the E. cloacae complex isolates into seven genogroup clusters, designated A-G. Among isolates assigned to genogroups A-D, 47/50 sequenced were colistin resistant, and many of those belonging to genogroups A-C identified as E. asburiae. Isolates belonging to genogroups E-G consistently identified as E. cloacae and were rarely (only 3/45 representatives sequenced) colistin resistant. Genogroups F and G, the predominant colistin-susceptible clusters, were metabolically distinct from other clusters, notably regarding utilization or not of l-fucose, formic acid, d-serine, adonitol, myo-inositol, l-lyxose and polysorbates. LPS from resistant organisms grown without colistin pressure lacked substitutions with 4-amino-arabinose or ethanolamine but was more structurally complex, with more molecular species present. CONCLUSIONS: Colistin resistance is frequent in the E. cloacae complex and increasing among bloodstream isolates. It is associated with: (i) particular genomic and metabolic clusters; (ii) identification as E. asburiae; and (iii) with more complex LPS architectures.

Item Type: Article
Additional Information: © The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
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Depositing User: LivePure Connector
Date Deposited: 27 Jun 2020 00:02
Last Modified: 24 Sep 2020 00:01
URI: https://ueaeprints.uea.ac.uk/id/eprint/75783
DOI: 10.1093/jac/dkaa201

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