Phenotypic and genotypic characterization of serologically atypical strains of Shigella flexneri type 4 isolated in Dhaka, Bangladesh - PubMed (original) (raw)

Phenotypic and genotypic characterization of serologically atypical strains of Shigella flexneri type 4 isolated in Dhaka, Bangladesh

Kaisar A Talukder et al. J Clin Microbiol. 2002 Jul.

Abstract

Twenty-one atypical Shigella flexneri type 4 strains isolated from patients attending the Dhaka treatment center of the International Centre for Diarrhoeal Disease Research, Bangladesh, were extensively characterized and compared with S. flexneri serotypes 4a and 4b. The atypical strains agglutinated only with the type antigen factor 4 and did not agglutinate with any group factors, thereby excluding their characterization into serotype 4a or 4b. Of the 21 strains, 85.7% did not ferment mannitol but were able to ferment most of the sugars, whereas the remaining 14.3% strains fermented mannitol but were unable to ferment most of the sugars. Most of the strains were resistant to ampicillin, tetracycline, and trimethoprim-sulfomethoxazole. All of the strains harbored the 140-MDa plasmid, had the ipaH gene, had the sen gene (encoding Shigella enterotoxin 2), had the ability to bind Congo red, and were positive for keratoconjunctivitis in the guinea pig eye, attesting their invasive properties. All of the strains contained a middle-range plasmid (35 to 62 MDa) as well as a number of stable small plasmids, yielding mainly two plasmid profiles which were different from those of 4a and 4b strains. Conjugation and curing experiments suggested that the middle-range plasmids harbored a self-transferable multiple antibiotic resistance marker. Pulsed-field gel electrophoresis analysis of all of the tested strains yielded two types with numerous subtypes, whereas ribotyping yielded only two types which were completely different from those of types 4a and 4b. This study concluded that two different clones of atypical S. flexneri type 4 exist and strongly suggests that these are new subserotypes of S. flexneri that await further serological classification.

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Figures

FIG. 1.

Ribotyping patterns of new subserotype of S. flexneri type 4 along with different serotypes of S. flexneri. Lanes: A, serotype 1a (strain K-647); B, serotype 1b (K-817); C, serotype 1c (K-212); D, serotype 2a (K-453); E, serotype 3a (K-452); F, S. flexneri ATCC 4a; G, S. flexneri NCTC 4b; H, S. flexneri type 4 (pattern R2); I, S. flexneri type 4 (pattern R1); J, serotype 5a (Y-787); K, serotype 6 (K-301); L, serotype Y (K-155); M, serotype X (K-608).

FIG. 2.

PFGE patterns of _Not_I-digested chromosomal DNAs from representative strains of atypical S. flexneri type 4 and reference strains. Lanes: A, K-282 (type A1); B, K-342 (type A1); C, K-361 (type A1); D, K-441 (type A1); E, K-472 (type A6); F, K-584 (type A2); G, ATCC 4a (type C); H, NCTC 4b (type D); I, molecular size marker (S. cerevisiae); J: K-716 (type B); K, K-772 (type A1); L, K-818 (type A5); M, K-820 (type A1).

References

1. Albert, M. J., N. A. Bhuiyan, K. A. Talukder, A. S. G. Faruque, S. Nahar, S. M. Faruque, M. Ansaruzzaman, and M. Rahman. 1997. Phenotypic and genotypic changes in Vibrio cholerae 0139 Bengal. J. Clin. Microbiol. 35**:**2588-2592. -PMC -PubMed
1. Ausubel, F. M., R. Brent, R. E. Kingston, D. D. Moore, J. G. Seidman, J. A. Smith, and K. Struhl. 1990. Current protocols in molecular biology, vol. 1. Greene Publishing Associates, New York, N.Y.
1. Bradbury, W. C., A. D. Pearson, M. A. Marko, R. V. Congi, and J. L. Penner. 1984. Investigation of a Campylobacter jejuni outbreak by serotyping and chromosomal restriction endonuclease analysis. J. Clin. Microbiol. 19**:**342-346. -PMC -PubMed
1. Carlin, N. I. A., A. A. Lindberg, K. Bock, and D. R. Bundle. 1984. The Shigella flexneri O-antigenic polysaccharide chain. Nature of the natural repeating unit. Eur. J. Biochem. 139**:**189-194. -PubMed
1. Carlin, N. I. A., M. Rahman, D. A. Sack, A. Zaman, B. A. Kay, and A. A. Lindberg. 1989. Use of monoclonal antibodies to type Shigella flexneri in Bangladesh. J. Clin. Microbiol. 27**:**1163-1166. -PMC -PubMed

Phenotypic and genotypic characterization of serologically atypical strains of Shigella flexneri type 4 isolated in Dhaka, Bangladesh - PubMed (original) (raw)