Microbiological changes and diversity in autochthonous non-toxigenic Corynebacterium diphtheriae isolated in France

Authors

  • E. Farfour,

    1. Institut Pasteur, Unité Prévention et Thérapies Moléculaires des Maladies Humaines, Centre National de Référence des Corynébactéries du Complexe Diphtheriae, Paris, France
    2. CNRS-URA 3012, Paris, France
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  • E. Badell,

    1. Institut Pasteur, Unité Prévention et Thérapies Moléculaires des Maladies Humaines, Centre National de Référence des Corynébactéries du Complexe Diphtheriae, Paris, France
    2. CNRS-URA 3012, Paris, France
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  • S. Dinu,

    1. ‘Cantacuzino’ National Institute of Research-Development for Microbiology and Immunology, Molecular Epidemiology Laboratory, Bucharest, Romania
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  • S. Guillot,

    1. Institut Pasteur, Unité Prévention et Thérapies Moléculaires des Maladies Humaines, Centre National de Référence des Corynébactéries du Complexe Diphtheriae, Paris, France
    2. CNRS-URA 3012, Paris, France
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  • N. Guiso

    Corresponding author
    1. Institut Pasteur, Unité Prévention et Thérapies Moléculaires des Maladies Humaines, Centre National de Référence des Corynébactéries du Complexe Diphtheriae, Paris, France
    2. CNRS-URA 3012, Paris, France
    • Corresponding author: N. Guiso, Institut Pasteur, Unité Prévention et Thérapies Moléculaires des Maladies Humaines, Centre National de Référence des Corynébactéries du Complexe Diphtheriae, CNRS-URA 3012, 25, rue du Dr Roux 75015 Paris, France

      E-mail: nicole.guiso@pasteur.fr

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Abstract

Autochtonous toxigenic Corynebacterium diphtheriae have disappeared in mainland France, but non-toxigenic C. diphtheriae are still circulating. Using phenotypic and molecular tools, we retrospectively characterized 103 non-toxigenic C. diphtheriae collected in mainland France and highlight several changes. The proportion of C. diphtheriae belfanti increased between 1977 and 2011 and it is the most frequent biotype recovered in recent years. Resistance to ciprofloxacin has increased and most isolates with decreased sensitivity belong to the belfanti biotype. Using multilocus sequence typing, we demonstrate that French isolates are distributed in a large number of sequence types and identify three distinct lineages. C. diphtheriae mitis and gravis form lineage I while C. diphtheriae belfanti forms lineages II and III. Almost all isolates of lineage II are part of a unique clonal complex or are very close to it. Most French isolates have a dtxR sequence homologous to that of toxigenic isolates, suggesting that if lyzogenised by a corynephage, they can express diphtheria toxin.

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