Characterization of the chromosomal cephalosporinases produced by Acinetobacter lwoffii and Acinetobacter baumannii clinical isolates.
The beta-lactamases produced by Acinetobacter lwoffii ULA-501, Acinetobacter baumannii ULA-187, and A. baumannii AC-14 strains were purified and characterized, and their kinetic interactions with several beta-lactam molecules, including substrates and inhibitors, were studied in detail. The three enzymes appeared to be cephalosporinases with different acylation efficiencies (kcat/Km ratio values), and their hydrolytic activities were inhibited by benzylpenicillin, piperacillin, and cefotaxime, which did not behave as substrates. Carbenicillin was a substrate for the beta-lactamase from A. lwoffii ULA-501, whereas it acted as a transient inactivator of the enzymes produced by the two A. baumannii strains. Clavulanic acid was unable to inactivate the three beta-lactamases, whereas sulbactam behaved as an inactivator only at a high concentration (1 mM) which is difficult to achieve during antibiotic therapy. Analysis of the interaction with 6-beta-iodopenicillanic acid also allowed us to better discriminate the three beta-lactamases analyzed in the present study, which can be included in the group 1 functional class (5).
Perilli
M
M
Dipartimento di Scienze e Tecnologie Biomediche e di Biometria, Università degli Studi dell'Aquila, Italy.
Felici
A
A
Oratore
A
A
Cornaglia
G
G
Bonfiglio
G
G
Rossolini
G M
GM
Amicosante
G
G
D000150:Acinetobacter / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D000151:Acinetobacter Infections / Q000382:microbiology; D001426:Bacterial Proteins / Q000378:metabolism; D002510:Cephalosporinase / Q000096:biosynthesis* / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000201:enzymology*; D019818:Clavulanic Acid; D002969:Clavulanic Acids / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007525:Isoelectric Focusing; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D013407:Sulbactam / Q000494:pharmacology; D018440:beta-Lactam Resistance; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000096:biosynthesis / Q000302:isolation & purification
D001426:Bacterial Proteins; D002969:Clavulanic Acids; D004791:Enzyme Inhibitors; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D002510:Cephalosporinase; D001618:beta-Lactamases; D013407:Sulbactam