Distribution of Serogroups of Vibrio cholerae non-O1 non-O139 with Specific Reference to Their Ability to Produce Cholera Toxin, and Addition of Novel Serogroups

Abstract

A total of 1898 strains of Vibrio cholerae non-O1 non-O139, which had been collected worldwide for the past 3 year period of 1994-1996, were serogrouped. The strains were also examined for presence of cholera toxin (CT) gene (ctx) and NAG-ST gene, and strains which carried to ctx were further analyzed for their ability to produce CT. In addition, attempts were made to establish novel serogroups for those serologically untypable strains. Of those examined, 1,774 strains of V. cholerae non-O1 non-O139 was classified into 128 known serogroups while 50 strains were found to belong to R type, and the rest of the 74 strains could not be serotyped. Distribution of the serogroups did not seem to correspond to either the strains geographic distribution or sources of isolation. Of those serologically untypable strains, 38 novel serogroups (O156-O193) were established and added to our reference of V. cholerae antigenic schema. It was also found that antisera raised against many V. cholerae strains included R antibodies. This indicates that any V. cholerae antisera for diagnostic purpose should be absorbed with the reference R strains, CA385, before use. There were luminescence producing strains among those sucrose and VP reaction negative strains. Subsequent DNA/DNA homology analysis revealed that they were identified as V. cholerae. This points to a possibility that strains tentatively identified as Vibrio mimicus by conventional biochemical tests may have included luminescent strains of V. cholerae. It is thus highly recommended that strains in question should be tested for the luminescence production in order to differentiate V. cholerae from V. mimicus. Of those 1989 strains examined, 37 strains (ca. 2%) were found to produce CT. Interestingly, CT producing strains were prevalent in serogroup O141; 10 strains out of 16 strains (63%) were positive for CT. The evidence calls for a caution to possible occurrence of cholera-like diarrhea caused by V. cholerae O141 in the future.

Fatal Diarrheal Disease Caused by <i>Vibrio cholerae</i> O67 in a Patient with Myelodysplastic Syndrome

“…According to a report by Yamai et al, Vibrio cholerae non-O1/non-O139 with the cholera toxin accounts for only 2% of the 1898 strains identified to date (10). Nevertheless, some patients with the same severe diarrhea as that caused by Vibrio cholerae O1 and O139 have been reported, which suggests the presence of intestinal virulence factors other than the cholera toxin (3,8).…”

Comparison of antibiogram, virulence genes, ribotypes and DNA fingerprints of Vibrio cholerae of matching serogroups isolated from hospitalised diarrhoea cases and from the environment during 1997–1998 in Calcutta, India

“…The species is currently classi®ed into 193`O' serogroups [1]. Of these, only the O1 and O139 serogroups are associated with clinical disease and this correlates with the fact that the majority of strains (.95%) in these serogroups produce cholera toxin (CT).…”

Distribution of virulence markers in clinical and environmental Vibrio cholerae non-O1/non-O139 strains isolated in Brazil from 1991 to 2000

“…The conventional method used to classify V. cholerae strains is a serotyping scheme based on epitopic variation cell surface lipopolysaccharide (LPS). Up to now, there is near 200 serogroups 37 and two serotypes (Inaba e Ogawa) identified for serogroup O1. The specie has been divided into serogroups O1 and non-O1 which differ each other for their ability to cause cholera epidemics 7 .…”