Comparative Genome Analysis and Global Phylogeny of the Toxin Variant Clostridium difficile PCR Ribotype 017 Reveals the Evolution of Two Independent Sublineages.
The diarrheal pathogen Clostridium difficile consists of at least six distinct evolutionary lineages. The RT017 lineage is anomalous, as strains only express toxin B, compared to strains from other lineages that produce toxins A and B and, occasionally, binary toxin. Historically, RT017 initially was reported in Asia but now has been reported worldwide. We used whole-genome sequencing and phylogenetic analysis to investigate the patterns of global spread and population structure of 277 RT017 isolates from animal and human origins from six continents, isolated between 1990 and 2013. We reveal two distinct evenly split sublineages (SL1 and SL2) of C. difficile RT017 that contain multiple independent clonal expansions. All 24 animal isolates were contained within SL1 along with human isolates, suggesting potential transmission between animals and humans. Genetic analyses revealed an overrepresentation of antibiotic resistance genes. Phylogeographic analyses show a North American origin for RT017, as has been found for the recently emerged epidemic RT027 lineage. Despite having only one toxin, RT017 strains have evolved in parallel from at least two independent sources and can readily transmit between continents.
['Cairns|M D|MD|', 'Preston|M D|MD|', 'Hall|C L|CL|', 'Gerding|D N|DN|', 'Hawkey|P M|PM|', 'Kato|H|H|', 'Kim|H|H|', 'Kuijper|E J|EJ|', 'Lawley|T D|TD|', 'Pituch|H|H|', 'Reid|S|S|', 'Kullin|B|B|', 'Riley|T V|TV|', 'Solomon|K|K|', 'Tsai|P J|PJ|', 'Weese|J S|JS|', 'Stabler|R A|RA|0000-0002-2402-6630', 'Wren|B W|BW|']
D000818:Animals D016360:Clostridioides difficile D003015:Clostridium Infections D014644:Genetic Variation D016680:Genome, Bacterial D014943:Global Health D006801:Humans D017720:Molecular Epidemiology D010802:Phylogeny D016133:Polymerase Chain Reaction D021521:Ribotyping D017422:Sequence Analysis, DNA
phylogeny Clostridium difficile ribotype 017 evolution sequencing phylogenetics antibiotic resistance SNPs