The role of Serratia marcescens porins in antibiotic resistance

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 accumulation assays, where semi-quantitative differences in accumulation were observed. Permeability coefficients to cephaloridine of Omp1 mutants were determined and compared with those of the parental strain. The clinical isolates S. marcescens HCPR1 and 866 showed 30- to 200-fold reduced permeability coefficients when Omp1 porin was absent

The role of Serratia marcescens porins in antibiotic resistance

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 accumulation assays, where semi-quantitative differences in accumulation were observed. Permeability coefficients to cephaloridine of Omp1 mutants were determined and compared with those of the parental strain. The clinical isolates S. marcescens HCPR1 and 866 showed 30- to 200-fold reduced permeability coefficients when Omp1 porin was absent

The role of Serratia marcescens porins in antibiotic resistance

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 accumulation assays, where semi-quantitative differences in accumulation were observed. Permeability coefficients to cephaloridine of Omp1 mutants were determined and compared with those of the parental strain. The clinical isolates S. marcescens HCPR1 and 866 showed 30- to 200-fold reduced permeability coefficients when Omp1 porin was absent

The role of Serratia marcescens porins in antibiotic resistance

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 accumulation assays, where semi-quantitative differences in accumulation were observed. Permeability coefficients to cephaloridine of Omp1 mutants were determined and compared with those of the parental strain. The clinical isolates S. marcescens HCPR1 and 866 showed 30- to 200-fold reduced permeability coefficients when Omp1 porin was absent

A mechanism of carbapenem resistance due to a new insertion element (ISPa133) in Pseudomonas aeruginosa

This study explored the evolutionary mechanism by which the clinical isolate PA110514 yields the imipenemresistant derivative PA116136. Both isolates were examined by PFGE and SDS-PAGE, which led to the identification of a new insertion sequence, ISPa133. This element was shown to have distinct chromosomal locations in each of the original isolates that appeared to explain the differences in imipenem susceptibilty. In strain PA110514, ISPa133 is located 56 nucleotides upstream of the translational start codon, which has no effect on expression of the porin OprD. However, in strain PA116136 ISPa133 it is located in front of nucleotide 696 and, by interrupting the coding region, causes a loss of OprD expression, thus conferring imipenem resistance. In vitro experiments mimicking the natural conditions of selective pressure yielded imipenem-resistant strains in which ISPa133 similarly interrupted oprD. A mechanism is proposed whereby ISPa133 acts as a mobile switch, with its position in oprD depending on the degree of selective pressure exerted by imipenem

A mechanism of carbapenem resistance due to a new insertion element (ISPa133) in Pseudomonas aeruginosa

This study explored the evolutionary mechanism by which the clinical isolate PA110514 yields the imipenemresistant derivative PA116136. Both isolates were examined by PFGE and SDS-PAGE, which led to the identification of a new insertion sequence, ISPa133. This element was shown to have distinct chromosomal locations in each of the original isolates that appeared to explain the differences in imipenem susceptibilty. In strain PA110514, ISPa133 is located 56 nucleotides upstream of the translational start codon, which has no effect on expression of the porin OprD. However, in strain PA116136 ISPa133 it is located in front of nucleotide 696 and, by interrupting the coding region, causes a loss of OprD expression, thus conferring imipenem resistance. In vitro experiments mimicking the natural conditions of selective pressure yielded imipenem-resistant strains in which ISPa133 similarly interrupted oprD. A mechanism is proposed whereby ISPa133 acts as a mobile switch, with its position in oprD depending on the degree of selective pressure exerted by imipenem

A mechanism of carbapenem resistance due to a new insertion element (ISPa133) in Pseudomonas aeruginosa

This study explored the evolutionary mechanism by which the clinical isolate PA110514 yields the imipenemresistant derivative PA116136. Both isolates were examined by PFGE and SDS-PAGE, which led to the identification of a new insertion sequence, ISPa133. This element was shown to have distinct chromosomal locations in each of the original isolates that appeared to explain the differences in imipenem susceptibilty. In strain PA110514, ISPa133 is located 56 nucleotides upstream of the translational start codon, which has no effect on expression of the porin OprD. However, in strain PA116136 ISPa133 it is located in front of nucleotide 696 and, by interrupting the coding region, causes a loss of OprD expression, thus conferring imipenem resistance. In vitro experiments mimicking the natural conditions of selective pressure yielded imipenem-resistant strains in which ISPa133 similarly interrupted oprD. A mechanism is proposed whereby ISPa133 acts as a mobile switch, with its position in oprD depending on the degree of selective pressure exerted by imipenem

A mechanism of carbapenem resistance due to a new insertion element (ISPa133) in Pseudomonas aeruginosa

This study explored the evolutionary mechanism by which the clinical isolate PA110514 yields the imipenemresistant derivative PA116136. Both isolates were examined by PFGE and SDS-PAGE, which led to the identification of a new insertion sequence, ISPa133. This element was shown to have distinct chromosomal locations in each of the original isolates that appeared to explain the differences in imipenem susceptibilty. In strain PA110514, ISPa133 is located 56 nucleotides upstream of the translational start codon, which has no effect on expression of the porin OprD. However, in strain PA116136 ISPa133 it is located in front of nucleotide 696 and, by interrupting the coding region, causes a loss of OprD expression, thus conferring imipenem resistance. In vitro experiments mimicking the natural conditions of selective pressure yielded imipenem-resistant strains in which ISPa133 similarly interrupted oprD. A mechanism is proposed whereby ISPa133 acts as a mobile switch, with its position in oprD depending on the degree of selective pressure exerted by imipenem

A mechanism of carbapenem resistance due to a new insertion element (ISPa133) in Pseudomonas aeruginosa

This study explored the evolutionary mechanism by which the clinical isolate PA110514 yields the imipenemresistant derivative PA116136. Both isolates were examined by PFGE and SDS-PAGE, which led to the identification of a new insertion sequence, ISPa133. This element was shown to have distinct chromosomal locations in each of the original isolates that appeared to explain the differences in imipenem susceptibilty. In strain PA110514, ISPa133 is located 56 nucleotides upstream of the translational start codon, which has no effect on expression of the porin OprD. However, in strain PA116136 ISPa133 it is located in front of nucleotide 696 and, by interrupting the coding region, causes a loss of OprD expression, thus conferring imipenem resistance. In vitro experiments mimicking the natural conditions of selective pressure yielded imipenem-resistant strains in which ISPa133 similarly interrupted oprD. A mechanism is proposed whereby ISPa133 acts as a mobile switch, with its position in oprD depending on the degree of selective pressure exerted by imipenem

A mechanism of carbapenem resistance due to a new insertion element (ISPa133) in Pseudomonas aeruginosa

This study explored the evolutionary mechanism by which the clinical isolate PA110514 yields the imipenemresistant derivative PA116136. Both isolates were examined by PFGE and SDS-PAGE, which led to the identification of a new insertion sequence, ISPa133. This element was shown to have distinct chromosomal locations in each of the original isolates that appeared to explain the differences in imipenem susceptibilty. In strain PA110514, ISPa133 is located 56 nucleotides upstream of the translational start codon, which has no effect on expression of the porin OprD. However, in strain PA116136 ISPa133 it is located in front of nucleotide 696 and, by interrupting the coding region, causes a loss of OprD expression, thus conferring imipenem resistance. In vitro experiments mimicking the natural conditions of selective pressure yielded imipenem-resistant strains in which ISPa133 similarly interrupted oprD. A mechanism is proposed whereby ISPa133 acts as a mobile switch, with its position in oprD depending on the degree of selective pressure exerted by imipenem

A mechanism of carbapenem resistance due to a new insertion element (ISPa133) in Pseudomonas aeruginosa

This study explored the evolutionary mechanism by which the clinical isolate PA110514 yields the imipenemresistant derivative PA116136. Both isolates were examined by PFGE and SDS-PAGE, which led to the identification of a new insertion sequence, ISPa133. This element was shown to have distinct chromosomal locations in each of the original isolates that appeared to explain the differences in imipenem susceptibilty. In strain PA110514, ISPa133 is located 56 nucleotides upstream of the translational start codon, which has no effect on expression of the porin OprD. However, in strain PA116136 ISPa133 it is located in front of nucleotide 696 and, by interrupting the coding region, causes a loss of OprD expression, thus conferring imipenem resistance. In vitro experiments mimicking the natural conditions of selective pressure yielded imipenem-resistant strains in which ISPa133 similarly interrupted oprD. A mechanism is proposed whereby ISPa133 acts as a mobile switch, with its position in oprD depending on the degree of selective pressure exerted by imipenem

A mechanism of carbapenem resistance due to a new insertion element (ISPa133) in Pseudomonas aeruginosa

This study explored the evolutionary mechanism by which the clinical isolate PA110514 yields the imipenemresistant derivative PA116136. Both isolates were examined by PFGE and SDS-PAGE, which led to the identification of a new insertion sequence, ISPa133. This element was shown to have distinct chromosomal locations in each of the original isolates that appeared to explain the differences in imipenem susceptibilty. In strain PA110514, ISPa133 is located 56 nucleotides upstream of the translational start codon, which has no effect on expression of the porin OprD. However, in strain PA116136 ISPa133 it is located in front of nucleotide 696 and, by interrupting the coding region, causes a loss of OprD expression, thus conferring imipenem resistance. In vitro experiments mimicking the natural conditions of selective pressure yielded imipenem-resistant strains in which ISPa133 similarly interrupted oprD. A mechanism is proposed whereby ISPa133 acts as a mobile switch, with its position in oprD depending on the degree of selective pressure exerted by imipenem

A mechanism of carbapenem resistance due to a new insertion element (ISPa133) in Pseudomonas aeruginosa

This study explored the evolutionary mechanism by which the clinical isolate PA110514 yields the imipenemresistant derivative PA116136. Both isolates were examined by PFGE and SDS-PAGE, which led to the identification of a new insertion sequence, ISPa133. This element was shown to have distinct chromosomal locations in each of the original isolates that appeared to explain the differences in imipenem susceptibilty. In strain PA110514, ISPa133 is located 56 nucleotides upstream of the translational start codon, which has no effect on expression of the porin OprD. However, in strain PA116136 ISPa133 it is located in front of nucleotide 696 and, by interrupting the coding region, causes a loss of OprD expression, thus conferring imipenem resistance. In vitro experiments mimicking the natural conditions of selective pressure yielded imipenem-resistant strains in which ISPa133 similarly interrupted oprD. A mechanism is proposed whereby ISPa133 acts as a mobile switch, with its position in oprD depending on the degree of selective pressure exerted by imipenem