Distribution of Serogroups and Serotypes of Multiple Drug Resistant Shigella Isolates

Abstract

Background: The distribution of Shigella sero-types is of epidemiological importance and antim-icrobial therapy for shigellosis can prevent poten-tial complications of shigellosis. Studies done fifty years ago in Ghana indicated the predominance of Shigella flexneri. Objectives: To describe the distribution of Shig-ella serogroups and serotypes and their anti-biogram profiles. Study design: A prospective descriptive study. Setting: The Microbiology Department of the Korle Bu Teaching Hospital. Methods: Consecutive stool specimens from pa-tients with diarrhoea submitted between February 2004 and June 2005 were cultured for Shigella and the isolates typed with commercial anti-sera. The susceptibilities of the isolates were also tested against eleven antimicrobial agents by the disc diffusion method. Minimum inhibitory concentra-tions (MIC) of isolates to ciprofloxacin were also determined by the E-test. Results: Five hundred and ninety four diarrhoea stool specimens yielded 24 Shigella isolates with the following serogroup distribution: S. flexneri 70.8%, S. dysenteriae 16.7%, S. sonnei 8.3% and S. boydii 4.2%. Approximately 96% of the isolates were multi-drug resistant but all twenty four were susceptible to nalidixic acid and the fluoroqui-nolones (ofloxacin and ciprofloxacin). The MICs of twenty one of the isolates to ciprofloxacin were ≤ 0.064 μg ml-1. Conclusions: The predominance of S. flexneri was confirmed and Shigella isolates from Accra are susceptible to nalidixic acid and the fluoroqui-nolones. Surveillance of antimicrobial resistance particularly to monitor the emergence of Shigella strains resistant to nalidixic acid and the fluoro-quiolones is important