Large-scale characterisation of hospital wastewater system microbiomes and clinical isolates from infected patients: profiling of multidrug-resistant microbial species

S. A. Kelly, N. H. O'Connell, T. P. Thompson, L. Dillon, J. Wu, C. Creevey, P. Kiely, B. Slevin, J. Powell, B. F. Gilmore, C. P. Dunne*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Background: Hospital-acquired infections (HAIs) and infectious agents exhibiting antimicrobial resistance (AMR) are challenges globally. Environmental patient-facing wastewater apparatus including handwashing sinks, showers and toilets are increasingly identified as sources of infectious agents and AMR genes. Aim: To provide large-scale metagenomics analysis of wastewater systems in a large teaching hospital in the Republic of Ireland experiencing multi-drug-resistant HAI outbreaks. Methods: Wastewater pipe sections (N=20) were removed immediately prior to refurbishment of a medical ward where HAIs had been endemic. These comprised toilet U-bends, and sink and shower drains. Following DNA extraction, each pipe section underwent metagenomic analysis. Findings: Diverse taxonomic and resistome profiles were observed, with members of phyla Proteobacteria and Actinobacteria dominating (38.23 ± 5.68% and 15.78 ± 3.53%, respectively). Genomes of five clinical isolates were analysed. These AMR bacterial isolates were from patients >48 h post-admission to the ward. Genomic analysis determined that the isolates bore a high number of antimicrobial resistance genes (ARGs). Conclusion: Comparison of resistome profiles of isolates and wastewater metagenomes revealed high degrees of similarity, with many identical ARGs shared, suggesting probable acquisition post-admission. The highest numbers of ARGs observed were those encoding resistance to clinically significant and commonly used antibiotic classes. Average nucleotide identity analysis confirmed the presence of highly similar or identical genomes in clinical isolates and wastewater pipes. These unique large-scale analyses reinforce the need for regular cleaning and decontamination of patient-facing hospital wastewater pipes and effective infection control policies to prevent transmission of nosocomial infection and emergence of AMR within potential wastewater reservoirs.

Original languageEnglish
Pages (from-to)152-166
Number of pages15
JournalThe Journal of Hospital Infection
Early online date17 Oct 2023
Publication statusPublished - Nov 2023

Bibliographical note

Funding Information:
This study was funded by the corresponding author at the School of Medicine in University of Limerick, and University Hospital Limerick.

Publisher Copyright:
© 2023 The Author(s)


  • AMR
  • Antimicrobial resistance
  • Hospital-acquired infection
  • Infection
  • Microbiome
  • Wastewater

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases


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