Resistance of Shigella strains to extended-spectrum cephalosporins in Isfahan province

Background: The aim of this study was to determine the serotypes and antimicrobial susceptibility of Shigella spp. in Isfahan, (Iran) from 2010 to 2015. Methods: This retrospective study was conducted on Shigella isolates in four tertiary care hospitals. The process of bacterial isolation and determination of susceptibility was performed by standard microbiological guidelines. The patients were categorized into three age groups of under 5, 5-15 and over 15 years. Results: Among 45 isolates, S. sonnei (63.6%) was the predominant species, followed by S. flexneri (34.1%), and S. dysenteriae (2.3%). Substantial resistance to ampicillin, trimethoprim- sulfamethoxazole, ceftriaxone, cefotaxime, and cefixime was observed. Over 94% of the isolates were sensitive to ciprofloxacin. Susceptibility of isolates was similar between all age groups. Conclusion: Significant resistance to third generation cephalosporins precludes the use of these agents for empirical treatment of shigellosis in our population. Ciprofloxacin is an appropriate option; however, susceptibility tests should be performed before prescription.