Abstract
BackgroundSporadic cases of infection with non-toxigenic Corynebacterium diphtheriae (C. diphtheriae) isolates have been reported in regions covered by the Diphtheria-Tetanus-Pertussis vaccine, but no information describing the whole genome of non-toxigenic strains collected in China is available. Therefore, in this work, the complete genome of a non-toxigenic strain of C. diphtheriae from a hospital located in southeastern China was performed.ResultsThis non-toxigenic isolate belonged to the belfanti biotype and possessed a unique ST (assigned as ST799 in pubMLST). ErmX was present in the genome sequence and this isolate owned the resistance to erythromycin and clindamycin. Genes coding for virulence factors involved in adherence, iron-uptake and regulation of diphtheria toxin were also found. Two genes were involved in the interaction between pathogen and host. The phylogenetic analysis revealed that this newly isolated strain was similar to the strain NCTC10838, CMCNS703 and CHUV2995.ConclusionNon-toxigenic C. diphtheriae strain contained virulence factors, thus it is able to cause an infectious disease, aspect that could be clarified by performing the whole genome sequencing analysis.
Highlights
Sporadic cases of infection with non-toxigenic Corynebacterium diphtheriae (C. diphtheriae) isolates have been reported in regions covered by the Diphtheria-Tetanus-Pertussis vaccine, but no information describing the whole genome of non-toxigenic strains collected in China is available
According to the blast results, the linear plasmid showed a sequence identity greater than 99% compared to two C. diphtheriae strains (ChUV2995) and subspecies lausannense strain (CMCN S703)
The susceptibility to erythromycin and clincamycin was determined by disk diffusion method. We found this isolated C. diphtheriae was both resistant to erythromycin and clindamycin
Summary
Sporadic cases of infection with non-toxigenic Corynebacterium diphtheriae (C. diphtheriae) isolates have been reported in regions covered by the Diphtheria-Tetanus-Pertussis vaccine, but no information describing the whole genome of non-toxigenic strains collected in China is available. Diphtheriae is usually caused by Coryneabacterium diphtheriae (C. diphtheriae) and it is a potentially lethal disease in children and adults when infected by toxinproducing strains [1]. It spreads among susceptible individuals, resulting in a high mortality in young children without vaccination [2]. The infection cases caused by the toxigenic strains declined after vaccine immunization program, but the current vaccines may not protect susceptible individuals from the non-toxigenic strains, which can cause severe disease [8, 9]. There were four biotypes (mitis, gravis, intermedius and belfanti) in clinical C. diphtheriae isolates, but the
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