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

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.

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.

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.

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.