Experimental studies on enteropathogenicity of Vibrio cholerae serotypes other than 1

Vibrio cholerae serotypes other than I have come to be recognised as an important aetiological agent of choleraic diarrhoea and a few of them have been shown to ben enterotoxigenic in experimental models. This study was taken up with strains belonging to all the known 59 serotypes. Live cells and culture filtrates of all the strains could cause accumulation of fluid in rabbit ileal loops. However, eleven strains did so after 1-2 serial passages in rabbit gut. All the culture filtrates could also cause increased vascular permeability. The toxin was found to be heat and pH labile. The pattern of time course of fluid accumulation in ileal loop and negative suckling mouse assay indicated that the enterotoxin was heat labile. Reduction of fluid outpouring by chlorpromazine but not by synthesis and receptor blockers of prostaglandin and 5-hydroxytryptamine indicated that the toxin may act through mediation of cAMP. All the 10 strains tested were negative in Sereny's test indicating lack of invasive capacity of these organisms.