Long-term dissemination of an OXA-40 carbapenemase-producing Acinetobacter baumannii clone in the Iberian Peninsula.
OBJECTIVE
The main objectives of this study were to assess the clonal relatedness of Acinetobacter baumannii carbapenem-resistant isolates recovered from the Iberian Peninsula and to investigate the production of carbapenemases.


METHODS
One hundred and sixty-two imipenem-resistant A. baumannii isolates were collected from 1998 to 2003 in three Portuguese university hospitals. An imipenem-resistant isolate (988FFP strain) recovered in 1995 from a smaller hospital unit, was also included, as well as an OXA-40-producing A. baumannii Spanish strain (SM28). Susceptibility tests were carried out by disc diffusion and Etest methods. DNA fingerprints were obtained by PFGE of ApaI-digested chromosomal DNA. Carbapenemase activity was determined by a bioassay and spectrophotometry. The detection of the blaOXA-40 gene was conducted through PCR analysis, cloning and nucleotide sequencing.


RESULTS
All the isolates presented a similar multi-resistance pattern, including imipenem (MIC >32 mg/L). The Iberian isolates showed an identical PFGE pattern with minor band variations, including isolate 988FFP collected in 1995. PCR results revealed a blaOXA-type gene in 65 isolates and nucleotide sequence analysis revealed the presence of the blaOXA-40 gene in seven representative Portuguese isolates from the various geographically dispersed hospitals.


CONCLUSIONS
Our results indicate that a multi-resistant epidemic clone of A. baumannii, carrying blaOXA-40, is disseminated in the Iberian Peninsula, persisting in Portugal since 1995.
Da Silva
G J
GJ
Laboratório de Microbiologia, Faculdade de Farmácia, Universidade de Coimbra and Centro de Estudos Farmacêuticos, Couraça dos Apóstolos, 51 r/c Esq., 3000-432 Coimbra, Spain. gjsilva@ci.uc.pt
Quinteira
S
S
Bértolo
E
E
Sousa
J C
JC
Gallego
L
L
Duarte
A
A
Peixe
L
L
D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D002876:Chromosomes, Bacterial / Q000235:genetics; D003428:Cross Infection / Q000382:microbiology; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D011174:Portugal / Q000453:epidemiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013030:Spain / Q000453:epidemiology; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015378:Imipenem; D001618:beta-Lactamases; C488541:beta-lactamase OXA-40, Acinetobacter baumannii; C063912:carbapenemase