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 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...

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Bibliographic Details
Published in:Journal of clinical microbiology 2017-03, Vol.55 (3), p.865-876
Main Authors: Cairns, M D, Preston, M D, Hall, C L, Gerding, D N, Hawkey, P M, Kato, H, Kim, H, Kuijper, E J, Lawley, T D, Pituch, H, Reid, S, Kullin, B, Riley, T V, Solomon, K, Tsai, P J, Weese, J S, Stabler, R A, Wren, B W
Format: Article
Language:English
Subjects:
Animals
Clostridioides difficile - classification
Clostridioides difficile - genetics
Clostridioides difficile - isolation & purification
Clostridium Infections - epidemiology
Clostridium Infections - microbiology
Clostridium Infections - veterinary
Epidemiology
Genetic Variation
Genome, Bacterial
Global Health
Humans
Molecular Epidemiology
Phylogeny
Polymerase Chain Reaction
Ribotyping
Sequence Analysis, DNA
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Summary:The diarrheal pathogen 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 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.
ISSN:0095-1137
1098-660X
DOI:10.1128/JCM.01296-16