Clinical evaluations of the wellcolex colour Shigella and Salmonella tests

Kocka, Frank E.; Dorigan, Francis D.; Abbasi, Qamar T.; Swiatlo, Andrea; Hubbard-Shepard, Marcia

doi:10.1016/0732-8893(92)90050-4

Cited by 10 publications

(3 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In that test, colored latex beads are coated with antibodies specific to each Shigella species, and identification depends on the color of the agglutination. Two recent studies (2,12) indicate that this product is sensitive and highly specific for the identification of Shigella isolates.…”

mentioning

confidence: 99%

Evaluation of commercial antisera for Shigella serogrouping

et al. 1995

View full text Add to dashboard Cite

Shigella serogrouping antisera from six companies (Becton Dickinson, Denka, Difco, Murex, Roach, and Sanofi-Pasteur) intended for the slide agglutination test and those of the Wellcolex Colour Shigella latex agglutination test were evaluated to identify quality products for Shigella identification. Forty-six reference Shigella strains (one for each serotype and species), 50 clinical strains (21 S. flexneri, 21 S. sonnei, 4 S. dysenteriae, 4 S. boydii) representing the most prevalent species and serotypes encountered in Quebec, and 9 non-Shigella strains were tested according to the manufacturers' instructions. A 3؉ reaction (>75% agglutination) was considered positive for the slide agglutination tests. Sensitivity varied from 47% (Roach) to 94% (Difco). For the 105 strains tested, accuracy ranged from 53% (Roach) to 91% (Wellcolex). Specificity varied from 97 to 100% for group A antisera, from 96 to 100% for group B antisera, from 88 to 100% for group C antisera, and from 95 to 99% for group D antisera. The costs of reagents required to test one strain varied from $3.50 to $13.20 (in Canadian dollars). In conclusion, Roach reagents proved to be unsatisfactory for Shigella serogrouping. Among those from the remaining companies, the Denka, Difco, and Wellcolex reagents met a performance standard of 90% accuracy. Shigella species are primarily responsible for gastrointestinal tract infections ranging from bacillary dysentery to less acute infections and are spread worldwide (1, 9-11, 13, 14). They share common characteristics with members of the genus Escherichia, from which they cannot be differentiated by DNA-DNA hybridization. According to modern taxonomy, subdivision of the genus into species is irrelevant. Nonetheless, medical and epidemiological interests justify maintaining the genus with its four species: S. dysenteriae, S. flexneri, S. boydii, and S. sonnei, also known as groups A, B, C, and D, respectively. These are subdivided into serotypes, which are given numerical designations (5-7, 13). Laboratory diagnosis relies on the isolation of the organism from feces and its identification by means of cultural and biochemical characteristics. Serological identification is mandatory because of its close relatedness to Escherichia coli. It requires, for a start, that species be identified (serogrouping); this is followed by serotype determination (serotyping). Serogrouping is generally carried out in clinical laboratories, while serotyping is performed in central or reference laboratories (5, 6, 13). Serogrouping is based on the detection of somatic O antigens by an agglutination technique with polyclonal antisera specific to each of the four Shigella species. Unfortunately, there is no international consensus on the choice of Shigella strains for the production of the grouping antisera (6). These antisera are commercially available from various manufacturers, but the sensitivities and specificities of these products remain to be determined. A study conducted by the U.S. Centers for Disease Control in 1988 (4) s...

show abstract

mentioning

confidence: 99%

Evaluation of commercial antisera for Shigella serogrouping

et al. 1995

View full text Add to dashboard Cite

show abstract

“…The many reports on Salmonella epidemics emphasize the need to improve conventional detection methods (3,17,20). Latex agglutination methods seem to facilitate the detection of salmonellae (1,5,9,12,13).…”

mentioning

confidence: 99%

“…Economies are furthermore possible relative to the use of bacteriophage reagents, biochemical screening tests, serological confirmation tests, and personnel time. In other studies, this test has also been successfully used to screen lactose-negative colonies on primary plates or for serological grouping (2,9). Selenite F broth subcultures should be maintained to confirm the Wellcolex Colour Salmonella Test result, to isolate and identify biochemically the Salmonella spp., and to detect the rare Salmonella groups not covered by the Wellcolex Colour Salmonella Test (<2%) (9).…”

mentioning

confidence: 99%

Evaluation of the Wellcolex Colour Salmonella Test for detection of Salmonella spp. in enrichment broths

1992

View full text Add to dashboard Cite

The Wellcolex Colour Salmonella Test was evaluated for detection of Salmonella spp. in enrichment broths of 1,010 stool samples. In 39 specimens, Salmonella spp. could be isolated from the selenite F broth (SF). Wellcolex agglutination indicative of the presence of Salmonella spp. was noted with the SF in 36 cases, 34 of which were in agreement with the subculture results. Therefore, relative to subculture, the sensitivity and specificity of the Wellcolex-selenite F procedure were 87 and 99%, respectively. Five false-negative results were noted. The gram-negative broth (GN) subculture revealed only 23 Salmonella spp. (59% sensitivity). The Wellcolex agglutination procedure applied to the GN indicated Salmonella spp. for 21 samples; its sensitivity was 70% and its specificity was 99% compared with GN subcultures. The Wellcolex agglutination procedure applied to the SF performed better than the agglutination of GN or direct plating procedures and detected 17 of the 39 Salmonella spp. at least 24 h earlier than did culture.

show abstract

Evaluation of a colour test for rapid detection of Salmonella

Orden

Franco

Juárez

et al. 1993

Eur. J. Clin. Microbiol. Infect. Dis.

View full text Add to dashboard Cite

The performance of a colour test (Wellcolex) for rapid detection of the most frequently isolated O serogroups of salmonella (A, B, C, D, E/G) and the Vi antigen was evaluated using colonies grown on enteric differential agar media and in selenite broth. The test had excellent sensitivity (100%) and specificity (100%) with colonies taken directly from primary culture plates. Initial tests in selenite broth showed limited sensitivity (62.1%) but by using high quality media and modifying the inoculation procedure, sensitivity was greatly improved (99%).

show abstract

Clinical evaluations of the wellcolex colour Shigella and Salmonella tests

Cited by 10 publications

References 4 publications

Evaluation of commercial antisera for Shigella serogrouping

Evaluation of commercial antisera for Shigella serogrouping

Evaluation of the Wellcolex Colour Salmonella Test for detection of Salmonella spp. in enrichment broths

Evaluation of a colour test for rapid detection of Salmonella

Contact Info

Product

Resources

About