A modified Elek test for detection of toxigenic corynebacteria in the diagnostic laboratory

Engler, Kathryn H.; Glushkevich, Tatiana; Мазурова, И К; George, Robert C.; Efstratiou, A

doi:10.1128/jcm.35.2.495-498.1997

Cited by 139 publications

(77 citation statements)

References 9 publications

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“…Bacterial isolates were identified as C. diphtheriae based on MALDI-TOF (cut-off 2.2) and the biotype determined biochemically using the API ® Coryne Strip (API bioMérieux). Toxin studies were carried out using the modified Elek test (11) and PCR for the diphtheria toxin gene (12).…”

Section: Methodsmentioning

confidence: 99%

Genome-wide comparison of toxigenic and non-toxigenicCorynebacterium diphtheriaeisolates identifies differences in the pan genomes between respiratory and cutaneous strains

Timms

Nguyen²,

Crighton³

et al. 2017

Preprint

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ObjectivesCorynebacterium diphtheriae is the main etiological agent of diphtheria, a global disease causing life-threatening infections, particularly in infants and children. Vaccination with diphtheria toxoid protects against infection with potent toxin producing strains. However a growing number of apparently non-toxigenic but potentially invasive C. diphtheriae strains are identified in countries with low prevalence of diphtheria, raising key questions about genomic structures and population dynamics of the species.MethodsThis study examined genomic diversity among 47 C. diphtheriae isolates collected in Australia over a 10-year period using whole genome sequencing. Phylogeny was determined using SNP-based mapping and genome wide analysis.ResultsC. diphtheriae sequence type (ST) 32, a non-toxigenic ST with evidence of enhanced virulence that is also circulating in Europe, appears to be endemic in Australia. Isolates from temporospatially related patients displayed the same ST and similarity in their core genomes. The genome-wide analysis highlighted a role of pilins, adhesion factors and iron utilization in infections caused by toxigenic as well as non-toxigenic strains.ConclusionsThe genomic diversity of toxigenic and non-toxigenic strains of C. diphtheriae in Australia suggests multiple local and overseas sources of infection and colonisation. Our findings suggest that regular genomic surveillance of co-circulating toxigenic and non-toxigenic C. diphtheriae can deliver highly nuanced data in order to inform targeted public health actions and policy for predicting the future impact of this highly successful pathogen.

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Section: Methodsmentioning

confidence: 99%

Genome-wide comparison of toxigenic and non-toxigenicCorynebacterium diphtheriaeisolates identifies differences in the pan genomes between respiratory and cutaneous strains

Timms

Nguyen²,

Crighton³

et al. 2017

Preprint

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“…Presence of the tox gene was investigated by real-time PCR [17]. Tox-positive strains were subsequently analysed for phenotypic expression of DT by a modified Elek test [40]. Thereby, all 34 WBC strains including C. silvaticum sp.…”

Section: Toxicitymentioning

confidence: 99%

Corynebacterium silvaticum sp. nov., a unique group of NTTB corynebacteria in wild boar and roe deer

Dangel¹,

Berger²,

Rau

et al. 2020

International Journal of Systematic and Evolutionary Microbiology

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A total of 34 Corynebacterium sp. strains were isolated from caseous lymph node abscesses of wild boar and roe deer in different regions of Germany. They showed slow growth on Columbia sheep blood agar and sparse growth on Hoyle’s tellurite agar. Cellular fatty acid analysis allocated them in the C. diphtheriae group of genus Corynebacterium . MALDI-TOF MS using specific database extensions and rpoB sequencing resulted in classification as C. ulcerans . Their quinone system is similar to C. ulcerans , with major menaquinone MK-8(H2). Their complex polar lipid profile includes major lipids phosphatidylinositol, phosphatidylinositol-mannoside, diphosphatidylglycerol, but also unidentified glycolipids, distinguishing them clearly from C. ulcerans . They ferment glucose, ribose and maltose (like C. ulcerans ), but do not utilise d-xylose, mannitol, lactose, sucrose and glycogen (like C. pseudotuberculosis ). They showed activity of catalase, urease and phospholipase D, but variable results for alkaline phosphatase and alpha-glucosidase. All were non-toxigenic, tox gene bearing and susceptible to clindamycin, penicillin and erythromycin. In 16SrRNA gene and RpoB protein phylogenies the strains formed distinct brancheswith C. ulcerans as nearest relative.Whole genome sequencing revealed the unique sequence type 578, a distinctbranch in pangenomic core genome MLST, average nucleotide identities <91%, enhancedgenome sizes (2.55 Mbp) and G/C content (54.4 mol%) compared to related species.These results suggest that the strains represent a novel species, for which wepropose the name Corynebactriumsilvaticum sp. nov., based on their first isolation from forest-dwellinggame animals. The type strain isKL0182T (= CVUAS 4292T = DSM 109166T = LMG 31313T= CIP 111 672T).

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“…On 26 March the isolate was sent on Amies transport medium to the National Reference Laboratory for Diphtheria at the Norwegian Institute of Public Health (NIPH), Oslo, and diphtheria toxin tox gene was detected by polymerase chain reaction (PCR) [1] on 28 March. Diphtheria toxin production was analysed by modified Elek test [2] and reported positive on 29 March. The strain was identified as C. diphtheriae biotype mitis by API Coryne v3 system (BioMérieux, France, code: 1010364) and supplementary tests (nitrate reduction positive, glycogen fermentation positive, not lipophilic and forming large colonies (>1 mm in diameter after 24 hours of incubation)).…”

Section: Laboratory Investigation At the National Reference Laboratorymentioning

confidence: 99%

Imported toxigenic cutaneous diphtheria in a young male returning from Mozambique to Norway, March 2014

et al. 2014

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In March 2014 a 20-year-old man was diagnosed with cutaneous diphtheria at St. Olavs University Hospital in Trondheim, Norway on his return from Africa. The man had been in Mozambique since autumn 2013 and had experienced persistent skin ulcer infections. His was in good general health. Toxin-producing Corynebacterium diphtheriae was grown from a wound specimen. He had completed the national childhood vaccination programme and received a diphtheria vaccine booster dose in 2005. Screening of close contacts revealed an asymptomatic person colonised with non-toxigenic C. diphtheriae.

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A modified Elek test for detection of toxigenic corynebacteria in the diagnostic laboratory

Cited by 139 publications

References 9 publications

Genome-wide comparison of toxigenic and non-toxigenicCorynebacterium diphtheriaeisolates identifies differences in the pan genomes between respiratory and cutaneous strains

Genome-wide comparison of toxigenic and non-toxigenicCorynebacterium diphtheriaeisolates identifies differences in the pan genomes between respiratory and cutaneous strains

Corynebacterium silvaticum sp. nov., a unique group of NTTB corynebacteria in wild boar and roe deer

Imported toxigenic cutaneous diphtheria in a young male returning from Mozambique to Norway, March 2014

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