Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2019

Emergence of Clostridium difficile ribotype 106 in Western Australia (#139)

Korakrit Imwattana 1 , Daniel R Knight 2 , Larry K Kociolek 3 4 , Egon A Ozer 5 , David W Eyre 6 7 , Thomas V Riley 1 2 8 9
  1. School of Biomedical Sciences, The University of Western Australia, Perth, WA, Australia
  2. School of Veterinary and Life Sciences, Murdoch University, Perth, WA, Australia
  3. Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, USA
  4. Division of Infectious Diseases, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, USA
  5. Department of Medicine, Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, USA
  6. Nuffield Department of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
  7. National Institute for Health Research (NIHR) Oxford Biomedical Research Centre, John Radcliffe Hospital, Oxford, UK
  8. School of Medical and Health Sciences, Edith Cowan University, Perth, WA, Australia
  9. Department of Microbiology, PathWest Laboratory Medicine, Perth, WA, Australia

Recently, there has been a shift in the epidemiology of Clostridium difficile infection in the United States, with C. difficile ribotype (RT) 106 becoming the most common strain of C. difficile isolated from adults and children with both community- and hospital-associated C. difficile infection, surpassing RT027. In Western Australia (WA), the first C. difficile RT106 strain was detected in September 2015 (1 case). Since then there has been an increase in the prevalence: 2016 (9 cases), 2017 (12 cases) and 2018 (19 cases). As part of an investigation into this rise in RT106 in WA, we performed whole-genome sequencing (WGS) and core genome typing on 12 selected RT106 strains from 5 hospitals in WA isolated during 2016 – 2018. For comparative analysis, we included genomes of RT106 circulating in the United Kingdom (UK) and the United States (US). Interestingly, the 12 RT106 strains could be further divided into 3 different, but closely related multilocus sequence types (ST): ST28 (n=6), ST42 (n=5) and ST 8 (n=1), the latter the first report of this ST within RT106. All ST 28 strains from WA were closely related, and two came from the same ward (separated by 55 days) and had no SNP differences, suggesting the spread within the hospital. Three ST 42 strains isolated from different patients (over 163 days) in different hospitals were also identical, suggesting, possibly, a common source of C. difficile. The remaining ST42 strains were distinct from one another. All RT106 strains from WA were different from the strains from the UK and US. These findings suggest that there may be at least two closely-related C. difficile lineages of RT106 in WA instead of a single strain. They also suggest that PCR ribotyping should only be used as a screening tool for C. difficile outbreaks and that WGS is needed for confirmation.