Phenotypic and Genotypic Characterization of Provisional Serotype <i>Shigella flexneri</i> 1c and Clonal Relationships with 1a and 1b Strains Isolated in Bangladesh

The serotypes of 144 strains of Shigella flexneri serotype 1 (serotypes 1a, 1b, and 1c) isolated from patients attending the Dhaka treatment center of the International Centre for Diarrhoeal Disease Research, Bangladesh, between 1997 and 2001 were serologically confirmed by using commercially available antisera and a panel of monoclonal antibodies specific for S. flexneri group and type factor antigen (MASF). Among serotype 1 isolates, the prevalence of provisional serotype S. flexneri 1c increased from 0 to 56% from 1978 to 2001 in Bangladesh. Detailed biochemical studies revealed that none of the strains of serotype 1 produced indole, while all the strains fermented mannose, mannitol, and trehalose. Twenty percent of the serotype 1c and all the serotype 1a strains fermented maltose…