A prospective study was conducted during 2009–12 in New Delhi, India, including 6339 stool samples from gastroenteritis patients. 121 Shigella strains were identified on the basis of colony morphology, biochemical reactions, serotyping and ipaH gene based PCR. Antimicrobial susceptibility testing by disc diffusion, MIC determination by Vitek® 2 and phenotypic tests for ESBL/AmpC production were done.
Nineteen percent strains (23/121) were found to be resistant to third generation cephalosporins and all were phenotypically confirmed to be ESBL producers; one strain was positive for AmpC. ESBL producing strains were also found to be significantly more resistant (p < 0.05) to several other antimicrobials agents in comparison to ESBL non-producers, [ampicillin (100% vs. 62.2%), ampicillin/sulbactam (100% vs. 30.6%), cotrimoxazole (100% vs. 77.6%), ciprofloxacin (87.0% vs. 49.0%), ofloxacin (87.0% vs. 52.0%) and gentamicin (30.4% vs. 7.1%)]. Multidrug resistance was seen in 76% strains.
Inappropriate use of antimicrobial agents puts high selection pressure on the higher-end antibiotics. Multi-drug resistance and high rates of ESBL production by Shigella is a matter of concern for the local population as well as international travelers. Therefore, better national level antimicrobial management programs are the priority needs.