Speicher, D.J., K. Luinstra, J. Maciejewski, K.K. Tsang, A.G. McArthur, & M. Smieja. 2019. Clostridioides difficile strain divergence over time. Oral presentation at the Association of Medical Microbiology and Infectious Disease Canada (AMMI Canada) & Canadian Association for Clinical Microbiology and Infectious Diseases (CACMID) Joint Annual Conference, Ottawa, Ontario.

Background: Clostridioides difficileinfection (CDI) is a serious hospital-associated infection with severe outbreaks caused by the hypervirulent NAP1/MLST-1 strain.  Whole genome sequencing has shown that most outbreak strains are clonal whereas non-outbreaks display a wide diversity of strains.  To examine strain diversity in clinical settings, a subset of C. difficileisolates from symptomatic CDI from an acute care hospital were compared to isolates from C. difficilecolonized (CDC) asymptomatic subjects from the same hospital.

Methods: A subset of PCR-positive stool samples from clinically confirmed CDI isolates from 2016 (13/110), 2017 (8/111), and 2018 (13/65), and CDC from 2017 (17/185) were cultured 3-times consecutively on CHROMagar™ C. difficile, sub-cultured on Columbia colistin-nalidixic acid (CNA) media, had DNA isolated, shotgun sequenced, and genome assembled for both MLST typing and genome-wide SNP phylogenetic analysis.

Results: Based on MLST profiles, the C. difficiletypes detected were diverse. Of the presumed binary toxin positive/NAP1 strains (i.e. PCR tcdA/tcdBpositive) 7/12 (58%) were NAP1/MLST-1 and 3/12 (25%) were NAP7/MLST-11.  NAP1/MLST-1 was not detected in any CDC isolate.  NAP4/MLST-2,14 were detected in 2016 (n=4), 2017 (n=2), 2018 (n=1), and in CDC isolates (n=3).  MLST-42 was dominant in CDC isolates (5/17; 29%) and decreased in prevalence in CDI isolates over time (2016=4; 2017=0; 2018=1).

Conclusion:  C. difficilestrains amongst both CDI and CDC individuals are highly divergent. Whilst molecular assays are misclassifying 25% of “NAP1” strains, both NAP1 and NAP7 are hypervirulent.  The number of MLST-42 CDC isolates is concerning as it has been reported to be the most common strain causing CDI among U.S. adults.  This highlights the need for continued genomic surveillance of both CDI and CDC individuals. Genome-wide SNP phylogenetic analysis is currently being performed.

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Congratulations to Rachel Tran on winning a 2019 DBCAD Summer Fellowship! These competitive awards are designed to support students working in the labs of members from both the David Braley Centre for Antibiotic Discovery and Michael G. DeGroote Institute for Infectious Disease Research during their summer practicum. A full list of awardees can be found here. Learn more about Rachel’s work at Ontario Biology Day 2019:

Tran, H.K.R., S. Ahmad, J.C. Whitney, & A.G. McArthur. 2019. Expanding the Virulence Ontology (VIRO) to determine the evolution of a secretion system effector. Presentation at Ontario Biology Day, London, Ontario, Canada.

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November 7, 2018; Hamilton, Ontario, Canada; The 9th annual McMaster Innovation Showcase, with focus on biomedical technologies, highlights the role and impact of McMaster research in shaping the future of healthcare. Hosted by the McMaster Industry Liaison Office (MILO) – supporting innovation, commercialization and community engagement. Photo by Ron Scheffler for McMaster University.

Congratulations to #TeamVirulence for winning the 2018 McMaster Innovation Showcase People’s Choice Poster Award for their poster entitled, “Examining the relationship between virulence and antimicrobial resistance via expansion of the Comprehensive Antibiotic Resistance Database (CARD)”! Left to right: Anatoly MiroshnichenkoHiu-Ki Rachel Tran, Sally Yue Min, and Rafik El Werfalli.

#TeamVirulence also presented their work at the 2018 Michael G. DeGroote Institute for Infectious Disease Research (IIDR) Trainee Day!

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Welcome #TeamVirulence, left to right: Rachel Tran (Biochem 3R06), Sally Min (BiomedDC 4A15), Anatoly Miroshnichencko (BiomedDC 4A15), and Rafik El Werfalli (BiomedDC 4A15), who are collectively working on development of CARD:Virulence, a new branch of the Comprehensive Antibiotic Resistance Database dedicated to the molecular surveillance of bacterial virulence factors.

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