title: Beta-lactamase-mediated resistance to extended spectrum cephalosporins among clinical isolates of Pseudomonas aeruginosa.
abstract: The role of chromosomal cephalosporinases and secondary beta-lactamases in resistance to extended spectrum cephalosporins in clinical isolates of Pseudomonas aeruginosa was investigated. Strains 687, 59, and 58 expressed an inducible chromosomal cephalosporinase, efficiently enhanced with cefoxitin and imipenem. The inducible activity in strain 802 was produced at a moderately elevated basal level and may be involved in resistance to extended spectrum cephalosporins and aztreonam. All strains produced secondary beta-lactamases inhibited by clavulanate: strains 687, 59, and 58 had carbenicillinases with pIs of 5.7 and 5.3. Strain 802 expressed a secondary beta-lactamase of pI 7.6 which may be a novel extended spectrum beta-lactamase different from known enzymes of P. aeruginosa.
authors.affiliation: Laboratoire de Biochimie et Technobiologie, Faculté des Sciences de Tunis, El-Manar II Tunis, Tunisia. belhadj@fst.rnu.tn
authors.forename: K
authors.initials: K
authors.lastname: Ben-Mahrez
authors.forename: S
authors.initials: S
authors.lastname: Rejiba
authors.forename: C
authors.initials: C
authors.lastname: Belhadj
authors.forename: O
authors.initials: O
authors.lastname: Belhadj
mesh_terms: D002439:Cefotaxime / Q000378:metabolism / Q000494:pharmacology*; D002442:Ceftazidime / Q000378:metabolism / Q000494:pharmacology*; D002443:Ceftriaxone / Q000378:metabolism / Q000494:pharmacology*; D018550:Cephalosporin Resistance; D002510:Cephalosporinase / Q000096:biosynthesis*; D004790:Enzyme Induction; D006801:Humans; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology*; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D002443:Ceftriaxone; D002442:Ceftazidime; D002510:Cephalosporinase; D001618:beta-Lactamases; D002439:Cefotaxime