Genomic Characteristics and Antibiotic Resistance Evolution of Vibrio cholerae O139 - Anhui Province, China, 2013-2024.

Cholera, a severe diarrheal disease caused by Vibrio cholerae, remains a major global public health concern. In 2023, the World Health Organization reported 535,321 cholera cases and 4,007 deaths in 45 countries. Sporadic cases and epidemic outbreaks of the cholera serogroup O139 have been documented in various Chinese provinces since 1993. This study analyzed the genomic features and antibiotic resistance patterns of 34 Vibrio cholerae O139 strains collected in Anhui Province between 2013 and 2024. The genetic sequences exhibited closer relationships to strains isolated from China than to those from India and Bangladesh, primarily forming two clusters. These strains contain multiple virulence factors, antimicrobial resistance (AMR) genes, and mobile genetic elements (MGEs). Notably, over 50% of the strains lacked the vgrG-2 gene in the type 6 secretion system (T6SS). Additionally, an increasing trend in azithromycin resistance was observed, whereas trimethoprim-sulfamethoxazole resistance showed a decreasing trend. Vibrio cholerae O139 in Anhui Province displayed genomic diversity indicative of domestic origin rather than cross-border transmission. While their pathogenicity is limited, these strains demonstrate robust colonization capabilities and the potential to disseminate AMR genes. The shift in AMR profiles driven by the clinical use of azithromycin poses an ongoing transmission risk for O139 strains and may foster the further emergence of AMR in the region.