conclusions although the data support the idea that the basic mechanism of imipenem resistance could be via the loss of oprd, they do not fully explain the role of oprd and indicate that other mechanisms may play an important role. additionally, the significant decrease in the oprd levels in mdr strains suggests that oprd also plays a role in the emergence of both carbapenem and non-carbapenem ...

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...

objective(s): we investigated the contribution of gyra and parc mutational mechanism in decreased ciprofloxacin susceptibility of acinetobacter baumannii isolated from burn wound infections. materials and methods: ciprofloxacin susceptibility of 50 a. baumannii isolates was evaluated by disk diffusion and agar dilution methods. pcr and sequencing were performed for detection of mutation in gyra...

A Tn501 mutant of Pseudomonas aeruginosa resistant to imipenem and lacking the imipenem-specific outer membrane porin protein OprD was isolated. The mutation could be complemented to imipenem susceptibility and OprD-sufficiency by a cloned 6-kb EcoRI-PstI fragment of DNA from the region of chromosome of the wild-type strain surrounding the site of Tn501 insertion. However, this fragment did not...

A series of clinical isolates of drug-resistant (DR) Acinetobacter baumannii with diverse drug susceptibility was detected from eight patients in the emergency intensive care unit of Tokai University Hospital. The initial isolate was obtained in March 2010 (A. baumannii Tokai strain 1); subsequently, seven isolates were obtained from patients (A. baumannii Tokai strains 2-8) and one isolate was...

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...

The metal-specific CzcRS two-component system in Pseudomonas aeruginosa is involved in the repression of the OprD porin, causing in turn carbapenem antibiotic resistance in the presence of high zinc concentration. It has also been shown that CzcR is able to directly regulate the expression of multiple genes including virulence factors. CzcR is therefore an important regulator connecting (i) met...

Pseudomonas aeruginosa can utilize arginine and other amino acids as both carbon and nitrogen sources. Earlier studies have shown that the specific porin OprD facilitates the diffusion of basic amino acids as well as the structurally analogous beta-lactam antibiotic imipenem. The studies reported here showed that the expression of OprD was strongly induced when arginine, histidine, glutamate, o...

conclusions the results of this study indicated that a decrease in oprd gene expression is an important mechanism of resistance in carbapenem resistant pseudomonas aeruginosa isolated from severe burn patients with secondary infection. results our study showed that 94.2% of the isolates were resistant to imipenem, 99.5% to meropenem, and all were resistant to ertapenem. the oprd gene expression...

An important question regarding the biologic implications of antibiotic-resistant microbes is how resistance impacts the organism's overall fitness and virulence. Currently it is generally thought that antibiotic resistance carries a fitness cost and reduces virulence. For the human pathogen Pseudomonas aeruginosa, treatment with carbapenem antibiotics is a mainstay of therapy that can lead to ...