We investigated the unusual susceptibility to meropenem observed for seven imipenem-resistant clinical isolates of Pseudomonas aeruginosa. These strains were genetically closely related, expressed OprD, as determined by Western blot analyses, and were resistant to imipenem (>5 microg/ml) but susceptible to meropenem (<1 microg/ml). The oprD genes from two isolates were entirely sequenced, and t...

background and objectives: the oprd mutation and ampc overproduction are the main mechanisms of intrinsic resistance to carbapenems such as imipenem and meropenem in pseudomonas aeruginosa . materials and methods: in this study, we investigated intrinsic resistance to carbapenems including mutation of oprd and ampc overproduction in a carbapenem-resistant p. aeruginosa isolated from a burn pati...

Earlier studies proved that Pseudomonas aeruginosa OprD is a specific porin for basic amino acids and imipenem. It was also considered to function as a nonspecific porin that allowed the size-dependent uptake of monosaccharides and facilitation of the uptake of quinolone and other antibiotics. In the present study, we utilized P. aeruginosa strains with genetically defined levels of OprD to cha...

Decreased permeability to imipenem is the most frequent mechanism of imipenem resistance in Pseudomonas aeruginosa. We have determined the presence of OprD porin protein, an imipenem influx channel, in 70 carbapenem-resistant P. aeruginosa clinical isolates by Western blot analysis using rabbit anti-OprD polyclonal antibody. Ninety-eight percent (54 of 55 isolates) of imipenem-and meropenem-res...

Pseudomonas aeruginosa OprD is a specific porin which facilitates the uptake of basic amino acids and imipenem, a carbapenem antibiotic. Resistance to imipenem due to the loss of OprD is an important mechanism for the loss of clinical effectiveness. To investigate the negative regulatory mechanisms influencing oprD expression, a gene upstream of the coregulated mexEF-oprN efflux operon, designa...

BACKGROUND Pseudomonas aeruginosa can become resistant to carbapenems by both intrinsic (mutation-driven) and transferable (β-lactamase-based) mechanisms. Knowledge of the prevalence of these various mechanisms is important in intensive care units (ICUs) in order to define optimal prevention and therapeutic strategies. METHODS A total of 109 imipenem-non-susceptible (MIC >4 mg/L) strains of P...

The increasing number of carbapenem-resistant Acinetobacter baumannii isolates is a major cause for concern which restricts therapeutic options to treat severe infections caused by this emerging pathogen. To identify the molecular mechanisms involved in carbapenem resistance, we studied the contribution of an outer membrane protein homologue of the Pseudomonas aeruginosa OprD porin. Suspected t...

Introduction: The major resistance mechanisms of Pseudomonas aeruginosa to fluoroquinolones and carbapenems are associated with the mutations in the genes gyrA and oprD encoding type II topoisomerases (DNA gyrase) and OprD porin, respectively. Method: In this cross-sectional study, sixty five clinical samples were collected from patients hospitalized in Al-Zahra Hospital of Isfahan, Iran. Susce...

Carbapenem-resistance is a great challenge for antimicrobial therapy in Pseudomonas aeruginosa multidrug-resistant infections, as it reduces therapeutic options. This study investigated carbapenem-resistance mechanisms six strains of non-carbapenemase-producing P. aeruginosa. Minimal inhibitory concentrations imipenem and meropenem were determined by epsilometric test broth microdilution. Mutat...

Mutant proteins with eight amino acid deletions in putative surface loops 2 and 3 of the imipenem-specific porin OprD of Pseudomonas aeruginosa failed to reconstitute imipenem susceptibility in an oprD-deficient background. The loop 3 deletion prevented the ability of imipenem to inhibit KCl conductance through the OprD channel, as previously shown for a loop 2 deletion. This suggests that both...