We investigated the synergism of colistin and imipenem against a multidrug-resistant K. pneumoniae isolate which was recovered from a severe hip infection. PCR and DNA sequencing were used to characterize the outer membrane porin genes and the resistance genes mediating the common β-lactamases and carbapenemases. Synergism was evaluated by time-kill studies. The bla SHV-31, bla CMY-2, and bla D...

Escherichia coli with direct electron transfer, a direct electrochemistry behavior in electrocatalysis of microbial fuel cells, underwent statistically significant up- and down-regulation of 107 genes, which suggests that the underlying cellular mechanisms include the regulation of outer membrane porin genes and terminal oxidase genes.

Typing of the porB variable region (VR) is an epidemiological tool that classifies gonococcal strains based on sequence differences in regions of the porB gene that encode surface-exposed loops. The frequent isolation of certain porB VR types suggests that some porin sequences confer a selective advantage during infection and/or transmission. Alternatively, certain porin types may be markers of...

The fitness cost of antibiotic resistance is a key parameter in determining the evolutionary success of resistant bacteria. Studies of the effect of antibiotic resistance on bacterial fitness are heavily biased toward target alterations. Here we investigated how the costs in the form of a severely impaired growth rate associated with resistance due to absence of two major outer membrane porins ...

The porin proteins of the pathogenic Neisseria species, Neisseria gonorrhoeae and Neisseria meningitidis, are important as serotyping antigens, putative vaccine components, and for their proposed role in the intracellular colonization of humans. A three-dimensional structural homology model for Neisseria porins was generated from Escherichia coli porin structures and N. meningitidis PorA and Po...

Antimicrobial treatment of Klebsiella pneumoniae infections can be complicated by the existence of multiply-antibiotic resistant (multiresistant) strains carrying plasmids coding for extended-spectrum β-lactamases (ESBLs), AmpC-type β-lactamases (ACTBLs), or aminoglycoside-modifying enzymes. This situation has become an increasingly serious problem worldwide with incidences ranging from 5% in t...

Extracellular electron transfer (EET) is recognized as a key biochemical process in circumneutral pH Fe(II)-oxidizing bacteria (FeOB). In this study, we searched for candidate EET genes in 73 neutrophilic FeOB genomes, among which 43 genomes are complete or close-to-complete and the rest have estimated genome completeness ranging from 5 to 91%. These neutrophilic FeOB span members of the microa...

Vibrio anguillarum serotype O2 strains express a 40-kDa outer membrane porin protein. Immunoblot analysis revealed that antigenic determinants of the V. anguillarum O2 40-kDa porin were conserved within bacterial species of the genus Vibrio. The relative amounts of the V. anguillarum O2 40-kDa porin were enhanced by growth of V. anguillarum O2 in CM9 medium containing 5 to 10% sucrose or 0.1 to...

Mitochondrial porin, the outer membrane pore-forming protein, was isolated in the presence of detergents and converted into a water-soluble form. This water-soluble porin existed under nondenaturing conditions as a mixture of dimers and oligomers. The proportion of dimers increased with decreasing porin concentration during conversion. Water-soluble porin inserted spontaneously into artificial ...

OBJECTIVES Multiply antibiotic-resistant (MAR) mutants of Escherichia coli and Salmonella enterica are characterized by reduced susceptibility to several unrelated antibiotics, biocides and other xenobiotics. Porin loss and/or active efflux have been identified as a key mechanisms of MAR. A single rapid test was developed for MAR. METHODS The intracellular accumulation of the fluorescent prob...