Characterization of the chromosomal cephalosporinases produced by Acinetobacter Iwoffii and Acinetobacter baumannii clinical isolates

Mariagrazia Perilli, Antonio Felici, Arduino Oratore, Giuseppe Cornaglia, Giovanni Bonfiglio, Gian Maria Rossolini, Gianfranco Amicosante

Research output: Contribution to journalArticle

Abstract

The β-lactamases produced by Acinetobacter Iwoffii ULA-501, Acinetobacter baumannii ULA-187, and A. baumannii AC-14 strains were purified and characterized, and their kinetic interactions with several β-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 β-lactamase from A. Iwoffii 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 β-lactamases, whereas sulbactam behaved as an inactivator only at a high concentration (1 niM) which is difficult to achieve during antibiotic therapy. Analysis of the interaction with 6-β-iodopenicillanic acid also allowed us to better discriminate the three β-lactamases analyzed in the present study, which can be included in the group 1 functional class (5).

Original languageEnglish
Pages (from-to)715-719
Number of pages5
JournalAntimicrobial Agents and Chemotherapy
Volume40
Issue number3
Publication statusPublished - Mar 1996

ASJC Scopus subject areas

  • Pharmacology (medical)

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