Surveillance and Genomic Characterisation of Colistin-Resistant Gram-Negative Bacteria in the Drains of High-Risk Hospital Units

ABSTRACT: Objective: The health care water environment, including sinks and drainage systems, can be a long-term reservoir of nosocomial pathogens. In this study, we aimed to investigate the presence of colistin-resistant Gram-negative (ColR-GN) bacteria in humid compartments of high-risk hospital...

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Main Authors: Giuseppe Fleres, Alessia Mirabile, Mariëtte Lokate, John W.A. Rossen, Natacha Couto, Alexander W. Friedrich, Silvia García-Cobos
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:Journal of Global Antimicrobial Resistance
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Online Access:http://www.sciencedirect.com/science/article/pii/S2213716525000475
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Summary:ABSTRACT: Objective: The health care water environment, including sinks and drainage systems, can be a long-term reservoir of nosocomial pathogens. In this study, we aimed to investigate the presence of colistin-resistant Gram-negative (ColR-GN) bacteria in humid compartments of high-risk hospital units at the University Medical Center Groningen, The Netherlands. Methods: Environmental sampling was conducted in sink and shower drains of high-risk hospital units, and colistin MICs were determined using broth microdilution. Whole-genome sequencing was performed to investigate the presence of mobile colistin resistance (mcr) genes, chromosomal point mutations and gene alterations linked to colistin resistance. Results: ColR-GN bacteria were detected in all investigated units, with Enterobacter spp. being the most abundant genus. Twelve isolates exhibited colistin resistance (MIC >2 mg/L), including Enterobacter cloacae complex (n = 11) and Klebsiella pneumoniae (n = 1). Chromosomal mutations in genes involved in lipopolysaccharide structure modifications were the main mechanisms contributing to colistin resistance in Enterobacter spp. and Klebsiella spp. (91.6%, 11/12). Additionally, two Enterobacter kobei isolates harboured mobile colistin resistance genes, mcr-4.3 and mcr-9.1. Conclusions: The presence and persistence of bacterial ColR-GN clones in the sink and shower drains of high-risk hospital units highlights the importance of monitoring such environments for antibiotic-resistant bacteria to identify reservoirs and prevent further spread.
ISSN:2213-7165