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Antimicrobial Agents and Chemotherapy, September 2009, p. 3908-3913, Vol. 53, No. 9
0066-4804/09/$08.00+0     doi:10.1128/AAC.00453-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Diversity of β-Lactamases Produced by Ceftazidime-Resistant Pseudomonas aeruginosa Isolates Causing Bloodstream Infections in Brazil {triangledown}

Renata C. Picão,1,2 Laurent Poirel,1 Ana C. Gales,2 and Patrice Nordmann1*

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,1 Laboratório ALERTA, Universidade Federal de São Paulo, São Paulo, Brazil2

Received 6 April 2009/ Returned for modification 2 May 2009/ Accepted 5 July 2009

A retrospective survey was conducted to characterize β-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 β-lactamase-mediated mechanism responsible for ceftazidime resistance in four isolates (9.3%). Nine isolates (20.9%) produced an extended-spectrum β-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-β-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 blaSPM-1 and blaCTX-M-2 genes, respectively, whereas the blaGES-1 and blaGES-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.

* Corresponding author. Mailing address: Service de Bactériologie-Virologie, Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre cedex, France. Phone: 33-1-45-21-36-32. Fax: 33-1-45-21-63-40. E-mail: nordmann.patrice{at}bct.aphp.fr

{triangledown} Published ahead of print on 13 July 2009.

Antimicrobial Agents and Chemotherapy, September 2009, p. 3908-3913, Vol. 53, No. 9
0066-4804/09/$08.00+0     doi:10.1128/AAC.00453-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Viedma, E., Juan, C., Acosta, J., Zamorano, L., Otero, J. R., Sanz, F., Chaves, F., Oliver, A. (2009). Nosocomial Spread of Colistin-Only-Sensitive Sequence Type 235 Pseudomonas aeruginosa Isolates Producing the Extended-Spectrum {beta}-Lactamases GES-1 and GES-5 in Spain. Antimicrob. Agents Chemother. 53: 4930-4933 [Abstract] [Full Text]  


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