We report here the emergence of VIM-2 and IMP-15 carbapenemases in a series of clinical isolates of carbapenem-resistant Pseudomonas aeruginosa in Lebanon. We also describe the disruption of the oprD gene by either mutations or insertion sequence (IS) elements ISPa1328 and ISPre2 isoform. Our study reemphasizes a rapid dissemination of the VIM-2 carbapenemase-encoding gene in clinical isolates ...

OBJECTIVES Although Pseudomonas aeruginosa from cystic fibrosis patients are well known for their antibiotic resistance, isolates that are highly susceptible to multiple drug classes have also been encountered. In this study, hypersusceptible P. aeruginosa isolates were analysed for changes in intrinsic resistance mechanisms to explain the observed phenotype. METHODS P. aeruginosa strains PA3...

Pseudomonas aeruginosa is a major opportunistic pathogen in hospital-acquired infections and exhibits increasing antibiotic resistance. A rapid and sensitive molecular method for its detection in clinical samples is needed to guide therapeutic treatment and to control P. aeruginosa outbreaks. In this study, we established a polymerase spiral reaction (PSR) method for rapid detection of P. aerug...

objective (s) porin is a mitochondrial outer membrane channel, which usually functions as the pathway for the movement of various substances in and out of the mitochondria and is considered to be a component of the permeability transition (pt) pore complex that plays a role in the pt. we addressed the hypothesis that porin interacts with other mitochondrial proteins after ischemic injury. mater...

Disruption of the PA2491 gene in a mini-Tn5-tet insertion mutant of a clinical isolate of Pseudomonas aeruginosa increased expression of the mexEF-oprN multidrug efflux genes and decreased production of outer membrane protein OprD, concomitant with enhanced resistance to chloramphenicol, quinolones, and imipenem, which was reminiscent of previously described nfxC mutants. PA2491 encodes a proba...

While meropenem MICs were strongly influenced by the presence or absence of the MexAB-OprM efflux pump in both OprD-proficient and -deficient strain backgrounds, MICs of imipenem and of ER-35786 remained unchanged, demonstrating that meropenem is a substrate of MexAB-OprM but not imipenem and ER-35786. In vitro, all three carbapenems selected loss of OprD as a first mechanism of resistance. How...

The oprP gene encoding the Pseudomonas aeruginosa phosphate-specific outer membrane porin protein OprP was sequenced. Comparison of the derived amino acid sequence with the known sequences of other bacterial porins demonstrated that OprP could be no better aligned to these porin sequences than it could to the periplasmic phosphate-binding protein PhoS of Escherichia coli. Southern hybridization...

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 patie...

We have isolated mutations in rpoA, the gene encoding the a subunit of RNA polymerase, that specifically affect transcriptional control by OmpR and EnvZ, the two-component regulatory system that controls porin gene expression in Escherichia coli. Characterization of these mutations and a previously isolated rpoA allele suggests that both positive and negative regulation of porin gene transcript...