Serotype distribution and antimicrobial resistance of Shigella isolates in Singapore.

Serogrouping of 506 Shigella strains isolated in Singapore from 1986 to 1990 showed that Shigella flexneri (60.3%) was the most common, followed by S. sonnei (33.6%), S. boydii (3.2%) and S. dysenteriae (3%). Of the 23 Shigella serotypes identified, the predominant ones were S. flexneri types 2a and 1b, S. boydii types 1 and 5, and S. dysenteriae types 1 and 3. More than 80% of the Shigella species were resistant to at least one antimicrobial drug, and the incidence of multiresistance was particularly high in S. flexneri strains. Due to the high incidence of antimicrobial resistance, the susceptibility pattern of Shigella strains should be determined for treatment purposes.