Imipenem and/or meropenem resistance has been observed commonly in nonfermenter species such as Pseudomonas aeruginosa (P. aeruginosa) and Acinetobacter spp. An increasing prevalence of carbapenems resistance mediated by acquired metallo-beta-lactamases (MBLs) is being reported particularly for Gram-negative rods in several countries. The aim of this study was to determine participation of MBLs in resistance to carbapenems of P. aeruginosa and Acinetobacter spp. and antimicrobial susceptibility to antibiotics.
Material and methods: A total 79 clinical strains of Gram-negative rods (P. aeruginosa and Acinetobacter spp.) with resistance to carbapenems (or reduced susceptibilities) were screen for ability to production of MBLs. Metallo-beta-lactamases were detected by using E-test (IP/IPI). The antibiotic susceptibilities determined by two methods: disc-diffusion and E-tests (only carbapenems).
Results: Three of 79 strains (3.8%) were MBLs-positive. All of MBLs-positive strains were characterized by multiresistance to tested antibiotics. Cefepime and gentamicin were the most active antibiotics. The results of susceptibility testing of MBLs-negative strains (carbapenems-resistant) showed the highest percentage of susceptibility to cefepime - 92.3% P. aeruginosa and 97.7% Acinetobacter spp.