Antimicrobial Activities and Mechanisms of Carbapenem Resistance in Clinical Isolates of Carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter spp.

Abstract

We tested the antimicrobial activities of meropenem (MEPM), imipenem (IPM), panipenem (PAPM), piperacillin (PIPC), cefepime (CFPM), aztreonam (AZT), amikacin (AMK), and levofloxacin (LVFX) against 106 clinical Pseudomonas aeruginosa isolates and 64 clinical Acinetobacter spp. isolates with reduced susceptibility to carbapenems. Using NCCLS breakpoints, the percentages of P. aeruginosa strains susceptible to AMK and Acinetobacter spp. strains susceptible to LVFX were found to be 51.1% and 55.6%, respectively, which represented the highest activity among 8 antimicrobial agents in each organism. Referring to the correlations among MICs of carbapenems, MEPM showed a higher activity than IPM and PAPM in both organisms; 29 of the 94 strains (30.9%) of IPM-resistant P. aeruginosa were susceptible to MEPM. Further study for resistance mechanisms to carbapenems by the disk diffusion method using 2-mercaptopropionic acid revealed that 8 of the 64 Acinetobacter spp. isolates (12.5%) were metallo-beta-lactamase producers, while none of 106 P. aeruginosa isolates were metallo-beta-lactamase producers. PCR analysis using blaIMP-specific primers confirmed that 4 of the 8 metallo-beta-lactamase-producing Acinetobacter spp. isolates detected by the disk diffusion method were carrying the blaIMP gene. The identification of metallo-beta-lactamase-producing Acinetobacter spp. isolates implies that metallo-beta-lactamase genes have been disseminated among various gram-negative pathogens.

Risk of transmission of imipenem-resistantPseudomonas aeruginosa through use of mobile bathing service

“…The MICs of these strains ranged from 16 to 32 μg/ ml, with the exception of one isolate, which had an MIC greater than 32 μg/ml. In Japan, 8.3% to 21.5% of IPM-resistant P. aeruginosa isolates were recovered from hospitals (17)(18)(19)(20). These IPM-resistant P. aeruginosa isolates were recovered from the urinary tract, skin and the respiratory tract (18)(19)(20).…”

Pseudomonas Aeruginosa and Newer β-Lactamases: An Emerging Resistance Threat

“…In Japan, Sugino et al, 2001 used only carbapenem non-susceptible isolates for screening of MBL. Hence we also used carbapenem resistant isolates for detection of MBL.…”