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Prevalence of binary toxin positive Clostridium difficile in diarrhoeal humans in the absence of epidemic ribotype 027

McGovern, A.M., Androga, G.O., Knight, D.R., Watson, M.W., Elliott, B., Foster, N.F., Chang, B.J. and Riley, T.V. (2017) Prevalence of binary toxin positive Clostridium difficile in diarrhoeal humans in the absence of epidemic ribotype 027. PLoS ONE, 12 (11). e0187658.

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Abstract

Virulence of Clostridium difficile is primarily attributed to the large clostridial toxins A and B while the role of binary toxin (CDT) remains unclear. The prevalence of human strains of C. difficile possessing only CDT genes (A−B−CDT+) is generally low (< 5%), however, this genotype is commonly found in neonatal livestock both in Australia and elsewhere. Zoonotic transmission of C. difficile has been suggested previously. Most human diagnostic tests will not detect A−B−CDT+ strains of C. difficile because they focus on detection of toxin A and/or B. We performed a prospective investigation into the prevalence and genetic characteristics of A−B−CDT+ C. difficile in symptomatic humans. All glutamate dehydrogenase or toxin B gene positive faecal specimens from symptomatic inpatients over 30 days (n = 43) were cultured by enrichment, and C. difficile PCR ribotypes (RTs) and toxin gene profiles determined. From 39 culture-positive specimens, 43 C. difficile isolates were recovered, including two A−B−CDT+ isolates. This corresponded to an A−B−CDT+ prevalence of 2/35 (5.7%) isolates possessing at least one toxin, 2/10 (20%) A−B− isolates, 2/3 CDT+ isolates and 1/28 (3.6%) presumed true CDI cases. No link to Australian livestock-associated C. difficile was found. Neither A−B−CDT+ isolate was the predominant A−B−CDT+ strain found in Australia, RT 033, nor did they belong to toxinotype XI. Previous reports infrequently describe A−B−CDT+ C. difficile in patients and strain collections but the prevalence of human A−B−CDT+ C. difficile is rarely investigated. This study highlights the occurrence of A−B−CDT+ strains of C. difficile in symptomatic patients, warranting further investigations of its role in human infection.

Publication Type: Journal Article
Murdoch Affiliation: School of Veterinary and Life Sciences
Institute for Immunology and Infectious Diseases
Publisher: Public Library of Science
Copyright: © 2017 McGovern et al.
UNSD Goals: Goal 3: Good Health and Well-being
URI: http://researchrepository.murdoch.edu.au/id/eprint/39389
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