Molecular characterization of Vibrio cholerae strains from clinical samples during the 2025 epidemic in the Republic of the Congo.

OBJECTIVES

The study aimed to determine the bacteriological and molecular profile of Vibrio cholerae strains responsible for the cholera outbreak that occurred in July 2025 in the Republic of the Congo.

METHODS

Fecal samples were collected from patients suspected of having cholera and admitted to health centers in four departments of the Republic of the Congo and sent to the National Public Health Laboratory for analysis. The samples were cultured, and the isolates obtained were subjected to serotyping and antibiotic susceptibility testing. Whole-genome sequencing was performed using the Illumina DNA Prep kit.

RESULTS

Of the 57 samples analyzed, 15 were phenotypically positive for V. cholerae O1 Ogawa and were confirmed by genotypic analysis. Phylogenetic analysis highlighted an epidemic clone closely related to Nigerian strains. The strains were resistant to ampicillin and nalidixic acid and sensitive to ciprofloxacin and doxycycline. All the strains carried the same resistance genes; however, one strain carried additional resistance genes. The virulence genes ctxA/B, tcpA/B, toxT, and zot were also identified in all the strains.

CONCLUSION

These results reveal the emergence of a virulent and multiresistant strain of V. cholerae O1 Ogawa in the Republic of the Congo, closely related to Nigerian strains. Its control requires cross-border coordination focused on genomic surveillance and mass vaccination.