Antimicrobial Resistance of Shigella Isolates in Alanya, Turkey

Abstract

Shigella spp. were isolated from stool samples and stored at −80 °C for antimicrobial susceptibility. Antimicrobial susceptibility was determined according to the Clinical and Laboratory Standards Institute criteria. The antimicrobials tested against Shigella spp. included ampicillin, trimethoprim–sulfamethoxazole, tetracycline, chloramphenicol, ciprofloxacin, ceftriaxone and azithromycin. Minimum inhibitory concentration of ceftriaxone and azithromycin were determined by E-test. Quality control was ensured by testing Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213. A total of 33 Shigella isolates (17 S. sonnei, 9 S. flexneri, 5 S. dysenteriae and 2 S. boydii) were assessed for their antimicrobial susceptibility patterns. The resistance to trimethoprim–sulfamethoxazole, ampicillin, tetracycline, chloramphenicol, ceftriaxone and azithromycin were found to be 66.7, 45.5, 57.6, 9.1, 9.1 and 3 %, respectively. S. sonnei showed higher resistance than S. flexneri to trimethoprim–sulfamethoxazole, but resistance to ampicillin was more common in S. flexneri than S. sonnei. Minimum inhibitory concentration values were in the following ranges: azithromycin 0.75–16 μg/mL and ceftriaxone 0.002 to >32 μg/mL. Minimum inhibitory concentration that inhibit 90 % of the strains for azithromycin and ceftriaxone were 6 and 0.47 μg/mL, respectively. The resistance to ceftriaxone and azithromycin may be a cause for concern.