The effects of imipenem and meropenem on the transcriptional expression of resistance-related genes oprD, oprM and oprN in Pseudomonas aeruginosa were studied by quantitative real-time PCR. Four strains were examined: the type strain PT5 (PAO1), its derivatives M7 and PT149, and a clinical isolate, PaKT3. The derivative M7 is a nalB mutant, overexpressing the MexAB-OprM pump, and the derivative...

We have described a gene coding for an Enterobacter cloacae protein, provisionally called OmpX (J. Stoorvogel, M. J. A. W. M. van Bussel, J. Tommassen, and J. A. M. van de Klundert, J. Bacteriol. 173:156-160, 1991). In the work reported here, OmpX was localized in the cell envelope by means of sucrose gradient fractionation of membrane vesicles. Overproduction of OmpX in Escherichia coli from a...

In this study, the contributions of different resistance mechanisms in Pseudomonas aeruginosa isolates were investigated among burned patients. The real-time reverse transcription polymerase chain reaction was performed to determine the expression level of mexY, ampC, and oprD for isolates. Also the isolates were typed by multilocus sequence typing (MLST). Seventy-five per cent of clinical isol...

A single vaccination of mice with a complex of porin and smooth lipopolysaccharide (porin-S-LPS) extracted from virulent Brucella abortus 2308 provided significant protection (P less than 0.01 to P less than 0.001) against challenge with the same strain, equivalent to that achieved by vaccination with living attenuated B. abortus 19. The porin-S-LPS vaccine given without adjuvant or in several ...

The outer membrane permeability of Serratia marcescens was studied by comparing porin-deficient mutants with their parental strains. Omp1-deficient strains were selected by moxalactam resistance, whereas mutants lacking the Omp2 porin were obtained by experimental infection with the SMP2 phage, whose primary receptor is the Omp2 porin. The role of porins was demonstrated in quinolone accumulati...

The modulating effect of N-acetylcysteine (NAC) on the activity of different antibiotics has been studied in Pseudomonas aeruginosa. Our results demonstrate that, in contrast to previous reports, only the activity of imipenem is clearly affected by NAC. MIC and checkerboard determinations indicate that the NAC-based modulation of imipenem activity is dependent mainly on OprD. SDS-PAGE of outer ...

Various ompF-ompC, ompC-ompF, and ompF-ompC-ompF chimeric genes were used to locate the domains of the OmpF protein involved in cellular sensitivity to colicins. Various parts of the porin participate in the entry of colicins. Colicin N receptor activity was found to require three regions: RN1, located between residues 1 and 63; RN2, located between residues 115 and 262; and RN3, located betwee...

introduction: neisseria meningitidis is a major causative agent of bacterial septicemia and meningitis in human. pora is a major component of the outer membrane of n. meningitidis and functions as a cationic porin. this study aimed to clone and determine the expression of pora as the first step for producing a proper antigen in a vaccine study against n. meningitidis. methods: an approximately ...

Escherichia coli porin OmpF and Pseudomonas aeruginosa porin protein P were eluted from sodium dodecyl sulfate-polyacrylamide gels. The resultant porin preparations were found to be devoid of detectable lipopolysaccharide (LPS) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining for LPS, direct enzyme-linked immunosorbent assays with LPS-specific monoclonal antibodi...

β-lactamase, altered porins, or both are usually responsible for cefoxitin resistance in Escherichia coli. We examined the relative importance of each. We studied 18 strains of clinical isolates with reduced cefoxitin susceptibility and 10 initially-susceptible strains passaged through cefoxitin-gradient plates. Of 18 wild-resistant strains, 9 had identical promoter mutations (including creatio...