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Prygiel M, Polak M, Mosiej E, Wdowiak K, Formińska K, Zasada AA. New Corynebacterium Species with the Potential to Produce Diphtheria Toxin. Pathogens 2022; 11:1264. [PMID: 36365015 PMCID: PMC9693595 DOI: 10.3390/pathogens11111264] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/20/2022] [Accepted: 10/27/2022] [Indexed: 07/30/2023] Open
Abstract
Only three Corynebacterium species are known to produce a lethal exotoxin called diphtheria toxin. These are C. diphtheriae, C. ulcerans and C. pseudotuberculosis. The diphtheria toxin gene (tox) is carried in a family of closely related corynebacteriophages and therefore the toxin can be produced only through lysogenisation, in which the corynephage encoding tox is stably inserted into the chromosome. However, 'nontoxigenic tox gene-bearing' (NTTB) strains, which are genotypically tox-positive but do not express the protein, have been described. The emergence of NTTB strains was first observed during the 1990s diphtheria epidemic in Eastern Europe and nowadays such isolates have been detected in many countries in the world. Recently, novel species of Corynebacterium genus have been described which might have the potential of producing the diphtheria toxin due to the possession of the diphtheria toxin gene but it has not produced toxin in laboratory tests. The circulation of NTTB strains could be related to the increased risk for diphtheria disease arising from the risk of re-emerging toxin expression. The article presents the mechanism of diphtheria toxin expression and action, recently described novel species of NTTB corynebacteria as well as the taxonomic changes within the C. diphtheriae group.
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Sharma NC, Efstratiou A, Mokrousov I, Mutreja A, Das B, Ramamurthy T. Diphtheria. Nat Rev Dis Primers 2019; 5:81. [PMID: 31804499 DOI: 10.1038/s41572-019-0131-y] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/25/2019] [Indexed: 01/09/2023]
Abstract
Diphtheria is a potentially fatal infection mostly caused by toxigenic Corynebacterium diphtheriae strains and occasionally by toxigenic C. ulcerans and C. pseudotuberculosis strains. Diphtheria is generally an acute respiratory infection, characterized by the formation of a pseudomembrane in the throat, but cutaneous infections are possible. Systemic effects, such as myocarditis and neuropathy, which are associated with increased fatality risk, are due to diphtheria toxin, an exotoxin produced by the pathogen that inhibits protein synthesis and causes cell death. Clinical diagnosis is confirmed by the isolation and identification of the causative Corynebacterium spp., usually by bacterial culture followed by enzymatic and toxin detection tests. Diphtheria can be treated with the timely administration of diphtheria antitoxin and antimicrobial therapy. Although effective vaccines are available, this disease has the potential to re-emerge in countries where the recommended vaccination programmes are not sustained, and increasing proportions of adults are becoming susceptible to diphtheria. Thousands of diphtheria cases are still reported annually from several countries in Asia and Africa, along with many outbreaks. Changes in the epidemiology of diphtheria have been reported worldwide. The prevalence of toxigenic Corynebacterium spp. highlights the need for proper clinical and epidemiological investigations to quickly identify and treat affected individuals, along with public health measures to prevent and contain the spread of this disease.
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Affiliation(s)
- Naresh Chand Sharma
- Laboratory Department, Maharishi Valmiki Infectious Diseases Hospital, Delhi, India
| | - Androulla Efstratiou
- WHO Collaborating Centre for Diphtheria and Streptococcal Infections, Reference Microbiology Division, Public Health England, London, UK
| | - Igor Mokrousov
- Laboratory of Molecular Epidemiology and Evolutionary Genetics, St. Petersburg Pasteur Institute, St. Petersburg, Russia
| | - Ankur Mutreja
- Global Health-Infectious Diseases, Department of Medicine, University of Cambridge, Cambridge, UK
| | - Bhabatosh Das
- Infection and Immunology Division, Translational Health Science and Technology Institute, Faridabad, India
| | - Thandavarayan Ramamurthy
- Infection and Immunology Division, Translational Health Science and Technology Institute, Faridabad, India.
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Tagini F, Pillonel T, Croxatto A, Bertelli C, Koutsokera A, Lovis A, Greub G. Distinct Genomic Features Characterize Two Clades of Corynebacterium diphtheriae: Proposal of Corynebacterium diphtheriae Subsp. diphtheriae Subsp. nov. and Corynebacterium diphtheriae Subsp. lausannense Subsp. nov. Front Microbiol 2018; 9:1743. [PMID: 30174653 PMCID: PMC6108181 DOI: 10.3389/fmicb.2018.01743] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 07/12/2018] [Indexed: 12/25/2022] Open
Abstract
Corynebacterium diphtheriae is the etiological agent of diphtheria, a disease caused by the presence of the diphtheria toxin. However, an increasing number of records report non-toxigenic C. diphtheriae infections. Here, a C. diphtheriae strain was recovered from a patient with a past history of bronchiectasis who developed a severe tracheo-bronchitis with multiple whitish lesions of the distal trachea and the mainstem bronchi. Whole-genome sequencing (WGS), performed in parallel with PCR targeting the toxin gene and the Elek test, provided clinically relevant results in a short turnaround time, showing that the isolate was non-toxigenic. A comparative genomic analysis of the new strain (CHUV2995) with 56 other publicly available genomes of C. diphtheriae revealed that the strains CHUV2995, CCUG 5865 and CMCNS703 share a lower average nucleotide identity (ANI) (95.24 to 95.39%) with the C. diphtheriae NCTC 11397T reference genome than all other C. diphtheriae genomes (>98.15%). Core genome phylogeny confirmed the presence of two monophyletic clades. Based on these findings, we propose here two new C. diphtheriae subspecies to replace the lineage denomination used in previous multilocus sequence typing studies: C. diphtheriae subsp. lausannense subsp. nov. (instead of lineage-2), regrouping strains CHUV2995, CCUG 5865, and CMCNS703, and C. diphtheriae subsp. diphtheriae subsp. nov, regrouping all other C. diphtheriae in the dataset (instead of lineage-1). Interestingly, members of subspecies lausannense displayed a larger genome size than subspecies diphtheriae and were enriched in COG categories related to transport and metabolism of lipids (I) and inorganic ion (P). Conversely, they lacked all genes involved in the synthesis of pili (SpaA-type, SpaD-type and SpaH-type), molybdenum cofactor and of the nitrate reductase. Finally, the CHUV2995 genome is particularly enriched in mobility genes and harbors several prophages. The genome encodes a type II-C CRISPR-Cas locus with 2 spacers that lacks csn2 or cas4, which could hamper the acquisition of new spacers and render strain CHUV2995 more susceptible to bacteriophage infections and gene acquisition through various mechanisms of horizontal gene transfer.
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Affiliation(s)
- Florian Tagini
- Institute of Microbiology, Department of Laboratory Medicine, Lausanne University Hospital, Lausanne University, Lausanne, Switzerland
| | - Trestan Pillonel
- Institute of Microbiology, Department of Laboratory Medicine, Lausanne University Hospital, Lausanne University, Lausanne, Switzerland
| | - Antony Croxatto
- Institute of Microbiology, Department of Laboratory Medicine, Lausanne University Hospital, Lausanne University, Lausanne, Switzerland
| | - Claire Bertelli
- Institute of Microbiology, Department of Laboratory Medicine, Lausanne University Hospital, Lausanne University, Lausanne, Switzerland
| | - Angela Koutsokera
- Division of Pulmonology, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Alban Lovis
- Division of Pulmonology, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Gilbert Greub
- Institute of Microbiology, Department of Laboratory Medicine, Lausanne University Hospital, Lausanne University, Lausanne, Switzerland
- Division of Infectious Diseases, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
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