Surveillance of travel-associated isolates elucidates the diversity of non-pandemic Vibrio cholerae

<i>Vibrio cholerae</i> is a Gram-negative bacterium found in aquatic environments and is the aetiological agent of cholera, characterized by acute watery diarrhoea and severe dehydration. Cholera presents a significant global health burden of an estimated 1.3-5 million annual cases, with the current pandemic caused by a toxigenic lineage of the O1 El Tor biotype called seventh pandemic El Tor (7PET) that is still ongoing. Whilst it is known that non-7PET lineages can cause sporadic disease, little is known about the transmission of these non-epidemic lineages. Thirty-four <i>V. cholerae</i> isolates were obtained from travellers returning from Indonesia to Australia between 2005 and 2017. These were whole genome sequenced, placed into a global phylogenetic context with 883 isolates, and screened for known genes associated with antimicrobial resistance and virulence. This analysis revealed that 30 isolates fell within non-7PET lineages and four within the 7PET lineage. Both 7PET and non-7PET isolates carried genes for resistance to antibiotics that are commonly used in cholera treatment such as tetracyclines and fluoroquinolones. Diverse virulence factors were also present in non-7PET isolates, with two isolates notably carrying toxin-coregulated pilus genes, which are primarily responsible for intestinal colonization in 7PET <i>V. cholerae</i>. This study demonstrates the role of travel in long-range carriage of epidemic and non-epidemic lineages of <i>V. cholerae,</i> and how sentinel travel surveillance can enrich our knowledge of <i>V. cholerae</i> diversity, reveal new biology about the spread of diverse lineages with differing disease potential and illuminate disease presence in endemic regions with limited surveillance data.