Genomic characterization of non-O1, non-O139 Vibrio cholerae causing rare clinical manifestation.

BACKGROUND: Non-O1, non-O139 Vibrio cholerae is an uncommon cause of pneumonia, particularly following freshwater exposure. Non-O1, non-O139 Vibrio cholerae was identified from bronchoalveolar lavage through culture and quantitative polymerase chain reaction (qPCR) in Hungary. During an epidemiological investigation, the source of infection was traced to a designated bathing site at a lake in Central Hungary, where non-O1,non-O139 Vibrio cholerae was isolated from surface water. METHODS: We conducted whole-genome sequencing and comparative genomic analysis on a clinical isolate (N = 1) and three phenotypically distinct environmental isolates (N = 3). In addition, we reviewed the available literature on pulmonary infections associated with Vibrio cholerae. RESULTS: Core genome multilocus sequence typing (cgMLST) revealed that the clinical and environmental isolates clustered together with zero allelic differences. Multilocus sequence typing (MLST) identified a new sequence type (ST1605), representing a novel combination of known allele variants. In silico analysis of antibiotic resistance genes identified the presence of blaCARB-7. Both the clinical and environmental isolates exhibited identical virulence gene profiles, reinforcing the hypothesis that the infection was acquired from a local water source. CONCLUSIONS: This study represents the first investigation of a primary pulmonary Vibrio cholerae infection reported in Europe following a near-drowning event. While Vibrio vulnificus and Vibrio metschnikovii have been implicated in similar pneumonia cases, the precise virulence mechanisms of these species remain poorly understood. Although non-O1, non-O139 Vibrio cholerae infections associated with recreational water exposure are rare in Hungary (1-2 cases per year), this study underscores the importance of ongoing surveillance for the detection of potential outbreaks and to inform public health responses.