Abstract

Shigellosis is very common in Andaman and Nicobar Islands, India. Two major species and serotypes, Shigella flexneriae 2a and Shigella dysenteriae type 1 were the cause of shigellosis in the Island till 2001. During 2002 to 2003, the scenario of shigellosis shifted and Shigella sonnei emerged as the prime and sole pathogen. On examination of 106 diarrhoeic stool samples, a total of seven S. sonnei was isolated. All the isolates were nalidixic resistant. The shift of predominant nalidixic acid-resistant trait of S. dysenteriae type 1 to S. sonnei had been observed in this study and was reported elsewhere (Ghosh et al., 2003). The present study aimed to study genotypic characterization of the nalidixic acid resistant S. sonnei. The molecular typing of isolated strains was carried out by plasmid profiling, random amplified polymorphic DNA (RAPD) and pulsed field gel electrophoresis (PFGE). The results revealed the clonality of the nalidixic acid-resistant S. sonnei. The study explores a note of caution to the public health for an epidemic due to nalidixic acid resistant S. sonnei in near future.

Key words: Nalidixic acid resistance, Shigella sonnei, dysenteric children.