Early identification of a ward-based outbreak of Clostridioides difficile using prospective multilocus sequence

Max Bloomfield1,2, Samantha Hutton1, Megan Burton1

  • 1Awanui Labs Wellington, Department of Microbiology and Molecular Pathology, Wellington, New Zealand.

Abstract

Insights

Genomic surveillance using Oxford Nanopore Technologies identified a Clostridioides difficile (CDI) outbreak. This system detected sequence type 2 CDI cases on a hemato-oncology ward, enabling targeted interventions.

Area of Science:

  • Infectious disease epidemiology
  • Genomic surveillance
  • Microbial genomics

Background:

  • Clostridioides difficile infection (CDI) poses a significant healthcare challenge.
  • Traditional surveillance methods may not detect localized outbreaks effectively.
  • Emerging genomic technologies offer new possibilities for real-time pathogen tracking.

Purpose of the Study:

  • To describe a Clostridioides difficile infection (CDI) outbreak.
  • To evaluate a prospective genomic surveillance system using Oxford Nanopore Technologies (ONT) and multilocus sequence typing (MLST).
  • To identify the specific sequence type (ST) involved in the outbreak.

Main Methods:

  • Prospective sequencing of all C. difficile isolates from inpatients using ONT MinION.
  • Real-time generation of MLST profiles.
  • Construction of ST-specific incidence charts using bed-movement data.
  • Retrospective phylogenetic analysis of outbreak-associated cases.

Main Results:

  • Between February and October 2022, 76 of 118 (64.4%) CDI cases were sequenced.
  • A predominance of ST2 CDI cases was identified among patients with hemato-oncology ward exposure.
  • Ten ST2 CDI cases were linked to the hemato-oncology ward.
  • No overall increase in CDI incidence was detected hospital-wide.
  • Phylogenetic analysis confirmed clustering of outbreak cases, excluding two.
  • Interventions, including a change in cleaning product, led to the cessation of new ST2 cases.

Conclusions:

  • Prospective genomic surveillance with ONT sequencing successfully identified an otherwise undetected ST2 CDI outbreak.
  • The MLST-based system enabled rapid detection and characterization of the outbreak.
  • Genomic surveillance is a valuable tool for controlling healthcare-associated infections.