Rapid screening method for identification of cholera toxin-producing Vibrio cholerae O1 and O139.
A novel method of identifying cholera enterotoxin (CT)-producing Vibrio cholerae serogroups O1 and O139 was developed. The method uses degradation of NAD as a specific biochemical marker for the CT-producing strains. The substrate NAD at a concentration of 100 mumol/liter was markedly degraded when it was incubated at 37 degrees C for 2 h with the CT-producing stains at a final cell density equivalent to that of a twofold dilution of a McFarland no. 1 standard. NAD degradation was monitored by an enzyme-amplified color development assay. Subsequent tests conducted with a total of 119 strains of V. cholerae, including both clinical and environmental isolates, confirmed a significant correlation between NAD degradation and CT production for all V. cholerae strains belonging to serogroups O1 and O139. Since 2 of 11 non-O1, non-O139 V. cholerae strains not carrying the CT gene degraded NAD, serotyping of the strains prior to the test is recommended.
Osawa
R
R
Department of Bacteriology and Pathology, Kanagawa Prefectural Public Health Laboratory, Yokohama, Japan.
Okitsu
T
T
Sata
S
S
Yamai
S
S
D015373:Bacterial Typing Techniques; D002772:Cholera Toxin; D014734:Vibrio cholerae / Q000145:classification / Q000302:isolation & purification*
D002772:Cholera Toxin