Minimum inhibitory concentration of carbapenems and tigecycline against Salmonella spp.

Abstract

Antimicrobial resistance in Salmonella spp. is of grave concern, more so in quinolone-resistant and extended-spectrum β-lactamase (ESBL)-producing isolates that cause complicated infections. The MIC of azithromycin, ciprofloxacin, cefixime, cefepime, ceftriaxone, gatifloxacin, imipenem, levofloxacin, meropenem and ofloxacin (E-test strip) and tigecycline and faropenem (agar dilution) against 210 Salmonella spp. was determined. MIC90 (defined as the antimicrobial concentration that inhibited growth of 90 % of the strains) of the carbapenems (imipenem and meropenem) for Salmonella Typhi and Salmonella Paratyphi A was 0.064 μg ml−1. MIC90 of faropenem was 0.25 μg ml−1 for S. Typhi, S. Paratyphi A and Salmonella Typhimurium. The MIC90 of azithromycin for all Salmonella spp. ranged from 8 to 16 μg ml−1. Tigecycline showed an MIC90 of 2 μg ml−1 for S. Typhi, 1 μg ml−1 for S. Paratyphi A and 4 μg ml−1 for S. Typhimurium. We concluded that tigecycline and the carbapenems are likely to have roles in the final stage of treatment of quinolone-resistant and ESBL-producing multidrug-resistant salmonellae.