Molecular epidemiology of Clostridioides difficile in border areas of Yunnan Province suggests possible transmission routes of the strains.

OBJECTIVES

A molecular epidemiological study of Clostridioides difficile was performed in the border areas of Yunnan Province.

METHODS

Molecular surveillance, bacterial isolation and identification, antibiotic susceptibility tests and genome sequencing of the isolates were performed.

RESULTS

Among the 788 total diarrhea patients, 97 (12.31 %) were positive for the tpi gene, and 86 (10.91 %) were positive for tcdB in the fecal samples. Forty-nine C. difficile strains were isolated, 38 of which were toxigenic (tcdA+/tcdB+) and 11 of which were nontoxigenic. Specifically, four binary toxin gene-positive C. difficile strains were first isolated in Hekou County of Yunnan. ST3, ST35 and ST2 were the most prevalent STs. The genotype profiles of C. difficile from the three border areas were different from those of the isolates from the inland areas of Yunnan, indicating obvious geographical divergence. cgMLST and core genome SNP phylogenetic analyses revealed that all strains formed three clades, namely, clades 1, 3 and 4. High genetic similarity of the same ST type of C. difficile in the three border regions was identified. The isolates from the border area presented high homology with isolates from inland areas and other provinces of China but were distant from the foreign reference strains, suggesting that the possible transmission route of the border strains was most consistent with dissemination from inland to border areas.

CONCLUSIONS

The genotype profiles of the strains differ across geographic regions. Phylogenetic analyses suggested that the border area strains presented high homology with inland strains from China.