title: Emergence of resistance to imipenem during therapy for Pseudomonas aeruginosa infections.
abstract: We studied the mechanism of resistance to imipenem in three clinical isolates of Pseudomonas aeruginosa. Two of these isolates arose from imipenem-susceptible strains isolated during therapy with imipenem and were associated with treatment failure. One of these two strains had previously been broadly resistant to beta-lactams; the second acquired resistance to imipenem alone. One isolate of the third strain was resistant to imipenem but susceptible to other antipseudomonal beta-lactams. No isolate contained beta-lactamase activity capable of hydrolyzing imipenem at a detectable rate. Studies of the penicillin-binding proteins of all isolates revealed no differences in the number of proteins, molecular weight of, affinity for penicillin, or affinity for imipenem in any isolate. In each case the resistant isolate lacked one or more outer membrane proteins that were present in a susceptible isolate of the same strain. The observed alterations in outer membrane proteins may be associated with diminished permeability of the bacterial outer membrane to imipenem and may be the major factor responsible for resistance in these isolates.
mesh_terms: D000328:Adult; D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism; D005260:Female; D006602:Hexosyltransferases; D006801:Humans; D015378:Imipenem; D008297:Male; D008875:Middle Aged; D002267:Muramoylpentapeptide Carboxypeptidase / Q000032:analysis / Q000378:metabolism; D010403:Penicillin Resistance; D046915:Penicillin-Binding Proteins; D010406:Penicillins / Q000378:metabolism; D010458:Peptidyl Transferases; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000032:analysis / Q000187:drug effects*; D013845:Thienamycins / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D013845:Thienamycins; D015378:Imipenem; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D001618:beta-Lactamases