Analysis of the serotype distribution and antibiotic resistance of Shigella in Changping district of Beijing in 2007　

Objective　The study was conducted to investigate the serotype distribution and antibiotic resistance of Shigella in Changping district, Beijing in 2007, providing evidence for the development of preventive measures and guidance for proper medication against bacillary dysentery. Methods　Shigella samples were cultured and isolated in SS agar and MC media. Serotyping and species indication was performed through biochemical and serological tests. Kirby-Bauer test, recommended by the Clinical and Laboratory Standards Institute(CLSI, the former NCCLS), was used as the susceptibility test. Results　The predominant Shigella strain in Changping district in 2007 was Shigella sonnei serogroup D, accouting for 62.75%; following was Shigella Flexneri serogroup B, accounting for 35.29%, consisting mostly of F4 and F1 subtypes. Four isolates of serotype X were identified, amounting to 22.22%, and one isolate was Shigella boydii serogroup C, accounting for 1.96%. Findings of the susceptibility test showed that those strains were sensitive to such seven antibiotics as ciprofloxacin, ofloxacin and levofloxacin, and were resistant to ampicillin, nalidixic acid, gentamicin, tetracycline and compound sulfamethoxazole. Conclusion　Having superseding Shigella flexneri serogroup B, Shigella sonnei serogroup D became the predominantly prevailing strain in Changping district in 2007. Meanwhile, subtypes F4 and F1 had superseded subtype 2a as the new prevailing serotypes in Shigella flexneri serogroup B. Both similarities and particularities can be found in the antibiotic resistance spectrum of Shigella when comparing the strains in Changping district with those in other regions of Beijing. Therefore, proper application of antibiotics would be essential in the treatment according to the results of local susceptibility tests.