Two porins, OmpK36 and OmpK35, have been described previously in Klebsiella pneumoniae, and they are homologous to the Escherichia coli porins OmpC and OmpF, respectively, at both the DNA and amino acid levels. Optimal resolution of the two K. pneumoniae porins by electrophoresis on polyacrylamide gels is not achieved using gel systems already described for E. coli and requires modifications of...

To detect the outer membrane protein (OMP), which plays a key role in carbapenem resistance, whole-genome and transcriptome analysis of the clinical carbapenem-resistant Klebsiella pneumoniae was carried out. The index strain lacked both OmpK35 and OmpK36, whereas the other strains lacked only OmpK35. After SDS-PAGE, the putative OMP bands were excised and identified as OmpA and OmpK36. MALDI-T...

OmpK35 from Klebsiella pneumoniae is the homologue of Escherichia coli OmpF porin. Expression of OmpK35 in K. pneumoniae strain CSUB10R (lacking both OmpK35 and OmpK36) decreased the MICs of cephalosporins and meropenem > or = 128-fold and decreased the MICs of imipenem, ciprofloxacin, and chloramphenicol > or = 8-fold. MIC reductions by OmpK35 were 4 times (cefepime), 8 times (cefotetan, cefot...

BACKGROUND The aims of this study were to confirm the presence of OmpK35 and OmpK36 in extended-spectrum beta-lactamase-producing and nonextended-spectrum beta-lactamase-producing Klebsiella pneumoniae and to determine the relationship between porin expression and resistance to third-generation cephalosporins. METHODS Fifty-two K. pneumoniae isolates were obtained and analyzed for extended-sp...

Klebsiella pneumoniae porin genes were analyzed to detect mutations accounting for the porin deficiency observed in many beta-lactam-resistant strains. PCR and Southern blot analysis revealed the existence of a third porin gene in addition to the OmpK36 and OmpK35 porin genes previously described. This new porin gene was designated ompK37 and is present in all of the clinical isolates tested. T...

OBJECTIVES The aims were to study if efflux and down-regulation of porins contribute to cefuroxime resistance in Klebsiella pneumoniae and to co-resistance to unrelated antibiotics. METHODS Ten cefuroxime-non-susceptible but cefotaxime-susceptible blood culture isolates of K. pneumoniae and one multiply antibiotic-resistant (MAR) laboratory strain (selected by chloramphenicol) were examined. ...

Klebsiella pneumoniae porin genes were analyzed to detect mutations accounting for the porin deficiency observed in many b-lactam-resistant strains. PCR and Southern blot analysis revealed the existence of a third porin gene in addition to the OmpK36 and OmpK35 porin genes previously described. This new porin gene was designated ompK37 and is present in all of the clinical isolates tested. The ...

BACKGROUND Emergence of carbapenems-resistant K. pneumoniae represents a serious challenge for antimicrobial therapy. OBJECTIVE The aim of this research is to determine different mechanisms mediating the emergence of K. pneumoniae isolates with high-level carbapenem resistance. METHOD A total of 80 K. pneumoniae isolates were purified from sputum and urine specimens. The minimum inhibitory ...