Prevalence of Shigella species and Antimicrobial Resistance Patterns of Isolated Strains from Infected Pediatrics in Tehran

Shigella is an infectious food-borne pathogen that can cause a severe diarrhea illness called shigellosis. The increasing levels of antimicrobial resistance of Shigella isolates have complicated the treatment of shigellosis. The antimicrobial resistance patterns of Shigella species vary according to geographic region and in the same place over time, leading to a therapeutic problem..This study attempts to determine the prevalence of shigellosis and the antimicrobial susceptibility pattern of isolated strains.. This cross- sectional study, with a 12-month duration, between August 2010 and August 2011 was carried out on 9131 infants with acute diarrheal disease. Stool samples were inoculated on selective and differential media. The Shigella isolates were identified and confirmed by biochemical laboratory tests. Subsequently, serotyping was performed with group specific antisera. Drug sensitivity test was carried out according to CLSI (2010) recommendations by using the standard disc diffusion method.. Shigella spp. were isolated from 90 (1%) of the 9131 stool samples collected from children with acute diarrhea. Among Shigella isolates, the most common subgroup was S. sonnei 63 (70%). Our results showed that imipenem, ciprofloxacin, ceftazidime and ceftizoxime are most effective antimicrobial agents against Shigella sp. The most frequent resistance observed, was towards co-trimoxazole (92.2%), ampicillin (65.6%) and tetracycline (65.6%).Since antibiotic resistant profile of Shigella varies geographically and also over time within a single country, regular, continuous surveillance is necessary. The results of accurate surveillance should be used to guide policies for antibiotic prescription..