The Pathogenicity of Nonenterotoxigenic Vibrio cholerae Serogroup 01 Biotype EI Tor Isolated from Sewage Water in Brazil

Abstract

Nonenterotoxigenic strains no. 1196-78 and no. 1074-78 of Vibrio cholerae serogroup O1 (biotype El Tor, serotype Ogawa) were isolated from sewage water in Brazil and fed to 20 volunteers. Neither strain caused diarrhea. None of the seven volunteers who ingested Ogawa strain no. 1074-78 (10(6) organisms) excreted the organism whereas eight of the 13 volunteers who ingested Ogawa strain no. 1196-78 (10(6) or 10(8) organisms) did excrete the organism in their stools. None of 114 stool-culture isolates yielded cholera enterotoxin, and none of the 20 volunteers had significant increases in serum titers of antitoxin as measured by enzyme-linked immunosorbent assay although six of the volunteers had slightly elevated vibriocidal antibody levels. Six volunteers used as controls and four volunteers who had stool cultures positive for strain no. 1196-78 of V. cholerae were challenged with pathogenic El Tor Ogawa strain no. E7946 (10(6) organisms) to determine if previous ingestion of the Brazilian strain would induce protective immunity. All 10 of the volunteers developed diarrhea, and the severity of the illness was similar in both groups.

New insights on the emergence of cholera in Latin America during 1991: the Peruvian experience.

“…In Peru (1984) 21 and Mexico (1987), 22 V. cholerae non-O1 was isolated from clinical specimens. Non-toxigenic V. cholerae O1 El Tor had been isolated from sewage in Brazil (1982) 23 and from two patients with diarrhea in Lima, Peru (1988). 24 These findings suggest that although both O1 and non-O1 V. cholerae had previously been cultured in this area of the world, the possibilities that these strains might be resident vibrios which acquired virulence genes through phage infection on a massive scale seems less likely.…”

Genetic diversity among toxigenic and nontoxigenicVibrio choleraeO1 isolated from the Western Hemisphere

“…In previous studies, atypical V. cholerae 01 isolates have often been included in the eltor biotype [10,25,26,42], implying that atypical strains are similar to the eltor biotype strains. Our results show that atypical and eltor biotype strains were present in both ET-1 and ET-8; otherwise genetic diversity apparently exists within both groups.…”

“…Since then, other non-toxigenic O1 strains have been reported to be isolated from cases of sporadic diarrhoeal disease [10,22] usually associated with seafood from the Gulf Coast regions [23]. In addition, nontoxigenic strains have been isolated in Brazil, Guam, Mexico, and Peru [24][25][26].…”

Role of Cholera Toxin in <i>Vibrio cholerae</i> Infection in Humans - A Review

“…Some isolates of V. cholerae O1 do not produce CTX and also do not possess the ctx genes encoding CTX (Kaper et al, 1981). Environmental strains are usually CTX negative and are considered to be nonpathogenic (Levine et al, 1982). However, CTXnegative V. cholerae O1 strains has been isolated from occasional cases of diarrhea (Morris et al, 1984) or extraintestinal infections.…”