TY - JOUR
T1 - Phenotypic and genotypic characterization of serologically atypical strains of Shigella flexneri type 4 isolated in Dhaka, Bangladesh
AU - Talukder, Kaisar A.
AU - Islam, M. Aminul
AU - Dutta, Dilip K.
AU - Hassan, Ferdaus
AU - Safa, Ashrafus
AU - Nair, G. B.
AU - Sack, David A.
PY - 2002
Y1 - 2002
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0036305308&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0036305308&partnerID=8YFLogxK
U2 - 10.1128/JCM.40.7.2490-2497.2002
DO - 10.1128/JCM.40.7.2490-2497.2002
M3 - Article
C2 - 12089268
AN - SCOPUS:0036305308
SN - 0095-1137
VL - 40
SP - 2490
EP - 2497
JO - Journal of clinical microbiology
JF - Journal of clinical microbiology
IS - 7
ER -