title: Diversity of beta-lactamases produced by ceftazidime-resistant Pseudomonas aeruginosa isolates causing bloodstream infections in Brazil.
abstract: A retrospective survey was conducted to characterize beta-lactamases in a collection of 43 ceftazidime-resistant Pseudomonas aeruginosa isolates recovered from patients with bloodstream infections hospitalized at a Brazilian teaching hospital between January and December 2005. Resistance rates for carbapenems, aminoglycosides, and quinolones were over 80%, with only colistin remaining active against all isolates. Pulsed-field gel electrophoresis analysis identified seven different genotypes. AmpC overproduction was found to be the sole beta-lactamase-mediated mechanism responsible for ceftazidime resistance in four isolates (9.3%). Nine isolates (20.9%) produced an extended-spectrum beta-lactamase (ESBL), either GES-1 (n = 7, 16.3%) or CTX-M-2 (n = 2, 4.6%). Carbapenemase activity was detected in 30 (70%) additional isolates. Among those isolates, two isolates (4.6%) produced the ESBL GES-5, possessing the ability to hydrolyze imipenem; a single isolate (2.3%) produced the metallo-beta-lactamase (MBL) IMP-1; and 27 isolates produced the MBL SPM-1 (62.8%). None of the isolates coproduced both ESBL and MBL. Insertion sequence elements ISCR4 and ISCR1 were associated with bla(SPM-1) and bla(CTX-M-2) genes, respectively, whereas the bla(GES-1) and bla(GES-5) genes were part of class 1 integron structures. This study underlines the spread of MBL- and ESBL-producing P. aeruginosa isolates as an important source of ceftazidime resistance in Brazil.
authors: Service de Bactériologie-Virologie, INSERM U914 Emerging Resistance to Antibiotics, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris Sud, K.-Bicêtre, France.
authors: Renata C
authors: RC
authors: Picão
authors: Laurent
authors: L
authors: Poirel
authors: Ana C
authors: AC
authors: Gales
authors: Patrice
authors: P
authors: Nordmann
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001938:Brazil; D015780:Carbapenems / Q000494:pharmacology; D002442:Ceftazidime / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D015363:Quinolones / Q000494:pharmacology; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D015363:Quinolones; D002442:Ceftazidime; D001618:beta-Lactamases; C063912:carbapenemase