title: Prevalence and pathogenicity of binary toxin-positive Clostridium difficile strains that do not produce toxins A and B.
abstract: Clostridium difficile causes antibiotic-associated diarrhoea and pseudomembranous colitis. The main virulence factors of C. difficile are the toxins A (TcdA) and B (TcdB). A third toxin, called binary toxin (CDT), can be detected in 17% to 23% of strains, but its role in human disease has not been clearly defined. We report six independent cases of patients with diarrhoea suspected of having C. difficile infection due to strains from toxinotype XI/PCR ribotype 033 or 033-like, an unusual toxinotype/PCR ribotype positive for CDT but negative for TcdA and TcdB. Four patients were considered truly infected by clinicians and were specifically treated with oral metronidazole. One of the cases was identified during a prevalence study of A(-)B(-)CDT(+) strains. In this study, we screened a French collection of 220 nontoxigenic strains and found only one (0.5%) toxinotype XI/PCR ribotype 033 or 033-like strain. The description of such strains raises the question of the role of binary toxin as a virulence factor and could have implications for laboratory diagnostics that currently rarely include testing for binary toxin.
authors.affiliation: Laboratoire associé « Clostridium difficile », Hôpital Saint Antoine, Assistance Publique-Hôpitaux de Paris, France ; UPMC Univ Paris VI, GRC n°2, Epidiff, France.
authors.forename: C
authors.initials: C
authors.lastname: Eckert
authors.affiliation: Laboratoire de Bactériologie, Virologie, Hygiène, Hôpital Henri Mondor, Assistance Publique-Hôpitaux de Paris, Créteil, France.
authors.forename: A
authors.initials: A
authors.lastname: Emirian
authors.affiliation: Laboratoire de Bactériologie, Groupe Hospitalier Paris Saint Joseph, Paris, France ; EA 4043, Université Paris-Sud 11, Faculté de Pharmacie, Châtenay-Malabry, France.
authors.forename: A
authors.initials: A
authors.lastname: Le Monnier
authors.affiliation: Laboratoire de Bactériologie, Hôpital Arnaud de Villeneuve, CHRU de Montpellier, France.
authors.forename: L
authors.initials: L
authors.lastname: Cathala
authors.affiliation: Laboratoire de Bactériologie, Centre Hospitalier de Bourg-en-Bresse, Bourg-en-Bresse, France.
authors.forename: H
authors.initials: H
authors.lastname: De Montclos
authors.affiliation: Laboratoire de Bactériologie, CHU de Bordeaux, Bordeaux, France.
authors.forename: J
authors.initials: J
authors.lastname: Goret
authors.affiliation: Institut Paoli-Calmettes, Marseille, France.
authors.forename: P
authors.initials: P
authors.lastname: Berger
authors.affiliation: Laboratoire associé « Clostridium difficile », Hôpital Saint Antoine, Assistance Publique-Hôpitaux de Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Petit
authors.affiliation: Laboratoire associé « Clostridium difficile », Hôpital Saint Antoine, Assistance Publique-Hôpitaux de Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: De Chevigny
authors.affiliation: Laboratoire de Bactériologie, Hôpital Arnaud de Villeneuve, CHRU de Montpellier, France ; UMR5119 ECOSYM, Equipe Pathogènes et Environnements, Université Montpellier 1, Montpellier, France.
authors.forename: H
authors.initials: H
authors.lastname: Jean-Pierre
authors.affiliation: Laboratoire de Bactériologie, Virologie, Hygiène, Hôpital Henri Mondor, Assistance Publique-Hôpitaux de Paris, Créteil, France.
authors.forename: B
authors.initials: B
authors.lastname: Nebbad
authors.affiliation: Laboratoire Alphabio, Marseille, France.
authors.forename: S
authors.initials: S
authors.lastname: Camiade
authors.affiliation: Service de Médecine Interne Maladies Infectieuses, Hôpital André Mignot, Le Chesnay, France.
authors.forename: R
authors.initials: R
authors.lastname: Meckenstock
authors.affiliation: Laboratoire associé « Clostridium difficile », Hôpital Saint Antoine, Assistance Publique-Hôpitaux de Paris, France ; Laboratoire de Microbiologie, Hôpital Saint Antoine, Assistance Publique-Hôpitaux de Paris, Paris, France.
authors.forename: V
authors.initials: V
authors.lastname: Lalande
authors.affiliation: Laboratoire de Bactériologie, Hôpital Arnaud de Villeneuve, CHRU de Montpellier, France ; UMR5119 ECOSYM, Equipe Pathogènes et Environnements, Université Montpellier 1, Montpellier, France.
authors.forename: H
authors.initials: H
authors.lastname: Marchandin
authors.affiliation: Laboratoire associé « Clostridium difficile », Hôpital Saint Antoine, Assistance Publique-Hôpitaux de Paris, France ; UPMC Univ Paris VI, GRC n°2, Epidiff, France ; Laboratoire de Microbiologie, Hôpital Saint Antoine, Assistance Publique-Hôpitaux de Paris, Paris, France.
authors.forename: F
authors.initials: F
authors.lastname: Barbut
keywords: A−B−CDT+ strains; Clostridium difficileI; PCR ribotype 033; binary toxin; diagnostic; toxinotype XI