The Pathogenicity of Ubol Type El Tor Vibrio

The pathogenicity of Ubol type El Tor vibrio which has been said to be non or less pathogenic was examined by using experimental cholera in mice and rabbits. Five strains were examined in their toxigenicity, infectivity (adhesive property to the intestinal epithelium) and pathogenicity (property to bring about symptom). At the same time, 5 strains of Celebes type El Tor vibrios were examined in the same way as the control study.Toxigenicity was determined with Syncase media and yeast extract enriched peptone water in vitro, and with the assay of cholera toxin in the intestinal fluid of infected rabbits. The adhesive property was determined with counting live vibrio adhered to the intestinal wall after washing in the physiological saline solution, and with electronmicroscopy. The pathogenicity was judged with the mortality of infected suckling mice and fluid accumulation in the intestine of rabbits. As the results, all Celebes type strains revealed positive findings; toxigenic, adhesive and pathogenic. Although 2 strains of Ubol type organism gave totally negative findings, 3 strains revealed positive as Celebes type organisms. Some of the pathogenic strains did not produce cholera toxin (less than 8 ng/ml) in vitro, but they produced much amount of cholera toxin in the rabbits intestine. Pathogenic strain, regardless the type, was toxigenic and adhesive. Non pathogenic strain lacked both properties. No strain had only one of them. In conclusion, the hypothesis “Ubol type El Tor vibrio is non or less pathogenic” should properly be corrected.