Whole genome sequence of a non-toxigenic Corynebacterium diphtheriae strain from a hospital in southeastern China

Abstract

Background 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. Therefore, in this work, the complete genome of a non-toxigenic strain of C. diphtheriae from a hospital located in southeastern China was performed. Results This 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. Conclusion Non-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.

Seroprevalence of Diphtheria and Tetanus Immunoglobulin G among the General Health Population in Guangzhou, China

“…In recent years, several older patients carrying non-pathogenic, non-toxigenic corynebacterium diphtheria have been reported in or near Guangdong, Guangzhou [4][5][6]. The monitoring data in China indicated that most of the tetanus patients were over 40 years old, with a relatively high case fatality rate [3].…”

“…The most recent diphtheria case nationwide was reported in 2006, down from the maximum of 70.7 thousand cases (11.1 per 100,000 people) recorded from 1950-1965 [3]. However, over the last few years, patients carried non-pathogenic, non-toxigenic corynebacterium diphtheria has been increasingly reported in China, 2018 in Dongyang [4], 2022 in Zhuhai [5], 2019 [6], 2023 and 2024 in Guangzhou. The research found that the ß-corynebacteriophage can infect non-toxigenic strains, which leads to transformation to a toxigenic strain and production of the diphtheria toxin [7].…”