Extraintestinal survival and host immune response to Vibrio cholerae

Vibrio cholerae is best known to cause the deadly disease cholera. However, in recent years this bacterial pathogen has been found to invade intestinal layers and translocate into the bloodstream of humans. The aim of this study was to investigate the molecular basis of V. cholerae bacteremia. Nine (9) strains of V. cholerae; six (6) environmental strains of non-O1/non-O139 serogroup and three (3) clinical strains of O1 serogroup and El-Tor serotype were screened for survival in serum obtained from immunocompromised patients. Serum from immunocompetent individuals with no known underlying conditions were used as healthy controls. Five (5) environmental strains and one (1) clinical strain of V. cholerae were identified to survive the bactericidal action of serum. Whole genome sequence analysis revealed the cholix toxin (ChxA) and genes encoding for siderophores (FepE and EntD) as possible virulence factors used by the environmental strains to cause invasive bloodstream infection. Peripheral blood mononuclear cells (PBMCs) stimulated with V. cholerae revealed increased expression of some cytokines; IL-1{beta} and IL-13 and the chemokine; RANTES especially among diabetics. The present study illustrates the potential survival of V. cholerae in blood, which could be aided by scavenging for iron from their host leading to severe infections.