Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2019

Laboratory-based surveillance of Clostridium difficile infection in the Australian healthcare and community settings in 2015 (#56)

Stacey Hong 1 2 , Steven Giglio 3 , Peter G Huntington 4 , Tony M Korman 5 , Despina Kotsanas 5 , Casey V Moore 6 , Graeme Nimmo 7 , Narelle George 7 , Louise Prendergast 8 , Jenny Robson 9 , Rodney McDougall 9 , Lynette Waring 8 , Christine Hemphill 8 , Michael C Wenrhahn 10 , Gerhard F Weldhagen 6 , Richard M Wilson 3 , Thomas V Riley 1 2 11 12 , Daniel R Knight 2
  1. School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, Australia
  2. Medical, Molecular and Forensic Sciences, Murdoch University, Perth, Western Australia, Australia
  3. Microbiology, Australian Clinical Labs, Adelaide, South Australia, Australia
  4. Microbiology, NSW Health Pathology - Royal North Shore Hospital, Sydney, New South Wales, Australia
  5. Monash Infectious Diseases, Monash Health - Monash Medical Centre, Melbourne, Victoria, Australia
  6. Microbiology and Infectious Diseases Laboratories, SA Pathology, Adelaide, South Australia, Australia
  7. Pathology Queensland, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
  8. Microbiology, Melbourne Pathology, Melbourne, Victoria, Australia
  9. Microbiology, Sullivan Nicolaides Pathology, Brisbane, Queensland, Australia
  10. Microbiology, Douglass Hanly Moir Pathology, Sydney, NSW, Australia
  11. School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia
  12. Microbiology, PathWest Laboratory Medicine, Perth, Western Australia , Australia


Objectives: As part of the ongoing national Clostridium difficile Antimicrobial Resistance Surveillance (CDARS) study, we sought to describe the molecular epidemiology of C. difficile infection (CDI) in the Australian healthcare and community settings in 2015.


Methods: Ten laboratories across Australia; one private and one public laboratory from five states submitted isolates of C. difficile or PCR positive stool samples during two collection periods for summer/autumn (February-March; CDARS phase 4) and winter/spring (August-September/ CDARS phase 5) 2015. C. difficile was characterized by PCR for toxin genes and ribotyping.


Results: A total of 307 eligible samples were received, of which 45% and 47% of the total collected were submitted by private laboratories from the two collection periods, respectively. From these samples, 285 isolates of C. difficile [WA (n=58), VIC (n= 55), SA (n=53), QLD (n=61) and NSW (n=56)] were recovered. PCR ribotyping yielded 71 different ribotypes (RTs) and 76% of strains (218/285) were assigned to 1 of 30 internationally recognised RTs. The most prevalent RTs were 014/020 (31%, n=88), 056 (8%, n=22) and 002 (7%, n=21). Epidemic RTs 027 (n=1), 078 (n=3) and the recently emerged RT251 (n=1) were found, as well as a single isolate of RT017. The vast majority (88%) of strains were positive for the major toxin genes tcdA/B, of which 4% (n=12) were also positive for genes encoding binary toxin (cdtA/B) and 7% (n=20) were non-toxigenic strains. Similar distributions were seen for RTs between states, although phase 5 appeared to have increased numbers of RTs 056 (n= 5 vs. 17) and 002 (n=6 vs. 15).


Conclusions: A heterogeneous C. difficile strain population was identified in Australia. RT014/020 was the most prevalent C. difficile strain found in humans with CDI. This successful lineage is also the most common RT in pigs in Australia, suggesting a potential zoonotic reservoir for human CDI. Continuous surveillance of circulating C. difficile strains is important for tracking of prominent and emerging strain types.