Abstract
Between November 2010, and May 2011, eleven cases of cholera, unrelated to a concurrent outbreak on the island of Hispaniola, were recorded, and the causative agent, Vibrio cholerae serogroup O75, was traced to oysters harvested from Apalachicola Bay, Florida. From the 11 diagnosed cases, eight isolates of V. cholerae were isolated and their genomes were sequenced. Genomic analysis demonstrated the presence of a suite of mobile elements previously shown to be involved in the disease process of cholera (ctxAB, VPI-1 and -2, and a VSP-II like variant) and a phylogenomic analysis showed the isolates to be sister taxa to toxigenic V. cholerae V51 serogroup O141, a clinical strain isolated 23 years earlier. Toxigenic V. cholerae O75 has been repeatedly isolated from clinical cases in the southeastern United States and toxigenic V. cholerae O141 isolates have been isolated globally from clinical cases over several decades. Comparative genomics, phenotypic analyses, and a Caenorhabditis elegans model of infection for the isolates were conducted. This analysis coupled with isolation data of V. cholerae O75 and O141 suggests these strains may represent an underappreciated clade of cholera-causing strains responsible for significant disease burden globally.
Highlights
Vibrio cholerae non-O1/non-O139 are the causative agents of sporadic, yet significant, gastrointestinal and extraintestinal infections globally, and it is well established that all strains of this species are capable of causing human infections that represent a significant global health burden [1,2,3,4,5,6,7]
Infection and subsequent illness caused by these organisms are linked to the presence of virulence factors in the core backbone of V. cholerae or mobile pathogenicity islands (VPIs-1 and 2, and CTXW) that are frequently found in clinical isolates from cholera patients suffering severe rice water diarrhea [8,9,10]
Results of the analysis demonstrate that the V. cholerae FL Group are sister taxa with V. cholerae V51, a clinical V. cholerae O141 serogroup strain isolated from a human clinical case in the United States in 1987, suggesting a common ancestor after it had diverged from other V. cholerae lineages
Summary
Vibrio cholerae non-O1/non-O139 are the causative agents of sporadic, yet significant, gastrointestinal and extraintestinal infections globally, and it is well established that all strains of this species are capable of causing human infections that represent a significant global health burden [1,2,3,4,5,6,7]. Infection and subsequent illness caused by these organisms are linked to the presence of virulence factors in the core backbone of V. cholerae (hemolysins, lipases) or mobile pathogenicity islands (VPIs-1 and 2, and CTXW) that are frequently found in clinical isolates from cholera patients suffering severe rice water diarrhea [8,9,10]. Epidemic cholera is typically ascribed to V. cholerae serogroup O1 or O139; it is understood that, similar to pathogenic Escherichia coli, a constellation of virulence factors along with host immune and nutritional status, are responsible for the severity and characteristic infections caused by these organisms [8,9,10,11,12].
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