Seeking the source of Pseudomonas aeruginosa infections in a recently opened hospital: an observational study using
Joshua Quick1, Nicola Cumley2, Christopher M Wearn3
1Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK NIHR Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital, Birmingham, UK.
Objectives:
Pseudomonas aeruginosa is a common nosocomial pathogen responsible for significant morbidity and mortality internationally. Patients may become colonised or infected with P. aeruginosa after exposure to contaminated sources within the hospital environment. The aim of this study was to determine whether whole-genome sequencing (WGS) can be used to determine the source in a cohort of burns patients at high risk of P. aeruginosa acquisition.
Study Design:
An observational prospective cohort study.
Setting:
Burns care ward and critical care ward in the UK.
Participants:
Patients with >7% total burns by surface area were recruited into the study.
Methods:
All patients were screened for P. aeruginosa on admission and samples taken from their immediate environment, including water. Screening patients who subsequently developed a positive P. aeruginosa microbiology result were subject to enhanced environmental surveillance. All isolates of P. aeruginosa were genome sequenced. Sequence analysis looked at similarity and relatedness between isolates.
Results:
WGS for 141 P. aeruginosa isolates were obtained from patients, hospital water and the ward environment. Phylogenetic analysis revealed eight distinct clades, with a single clade representing the majority of environmental isolates in the burns unit. Isolates from three patients had identical genotypes compared with water isolates from the same room. There was clear clustering of water isolates by room and outlet, allowing the source of acquisitions to be unambiguously identified. Whole-genome shotgun sequencing of biofilm DNA extracted from a thermostatic mixer valve revealed this was the source of a P. aeruginosa subpopulation previously detected in water. In the remaining two cases there was no clear link to the hospital environment.
Conclusions:
This study reveals that WGS can be used for source tracking of P. aeruginosa in a hospital setting, and that acquisitions can be traced to a specific source within a hospital ward.
Insights
Whole-genome sequencing (WGS) effectively traced Pseudomonas aeruginosa hospital-acquired infections to their environmental sources. This method identified specific contamination points, like water systems, aiding in infection control for high-risk patients.
Area of Science:
- Medical Microbiology
- Genomics
- Infectious Disease Epidemiology
Background:
- Pseudomonas aeruginosa is a significant cause of hospital-acquired infections, leading to severe illness and death.
- Patient acquisition of P. aeruginosa often stems from contaminated hospital environments.
Purpose of the Study:
- To evaluate the utility of whole-genome sequencing (WGS) for identifying the source of P. aeruginosa acquisition in burns patients.
- To investigate the link between environmental P. aeruginosa and patient infections within a hospital setting.
Main Methods:
- An observational prospective cohort study was conducted in UK burns and critical care wards.
- Patients with >7% total body surface area burns were recruited; P. aeruginosa screening included patients and their immediate environment (e.g., water).
- Isolates underwent whole-genome sequencing, with phylogenetic analysis to determine relatedness and potential sources.
Main Results:
- Whole-genome sequencing of 141 P. aeruginosa isolates from patients and the environment revealed eight distinct phylogenetic clades.
- Identical genotypes were found between patient and water isolates, with clear clustering by room and water outlet, pinpointing contamination sources.
- Biofilm sequencing identified a thermostatic mixer valve as the source of P. aeruginosa in the water supply.
Conclusions:
- Whole-genome sequencing is a powerful tool for tracing P. aeruginosa sources in healthcare settings.
- Acquisitions of P. aeruginosa in hospital wards can be definitively linked to specific environmental origins.
