title: Carbenicillin resistance of Pseudomonas aeruginosa.
abstract: Four strains of Pseudomonas aeruginosa obtained from clinical isolates which are carbenicillin resistant were studied to find the cause(s) of resistance to this beta-lactam antibiotic. The electrophoresis patterns of the four strains (PH20610, PH20815, PH4011, and PH4301) were found to be different from those of a wild-type strain, P. aeruginosa NCTC 10662, and appeared to lack penicillin-binding protein 2. Affinity of other penicillin-binding proteins from strains PH20610 and PH20815 for carbenicillin seemed to be normal or slightly diminished. Electrophoretic patterns of penicillin-binding proteins from strains PH4011 and PH4301 had more profound differences, since the affinities of their penicillin-binding proteins 1a, 1b, and 4 for carbenicillin were decreased by nearly two orders of magnitude relative to the preparations from the wild-type strain. Kinetic studies on binding of carbenicillin to penicillin-binding proteins both in isolated membrane preparations and in intact cells revealed that carbenicillin penetration into resistant cells was a much slower process than in susceptible cells, suggesting that the outer envelope structures serve as an efficient barrier against carbenicillin entry into our P. aeruginosa strains from clinical isolates.
mesh_terms: D001426:Bacterial Proteins; D002228:Carbenicillin / Q000378:metabolism / Q000494:pharmacology*; D002352:Carrier Proteins / Q000302:isolation & purification / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D004591:Electrophoresis, Polyacrylamide Gel; D006602:Hexosyltransferases; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D002267:Muramoylpentapeptide Carboxypeptidase / Q000302:isolation & purification / Q000378:metabolism; D010403:Penicillin Resistance; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D001618:beta-Lactamases; D002228:Carbenicillin