ABSTRACT
A recent collection of 213 imipenem-resistant Acinetobacter baumannii (IRAB) clinical isolates was characterized for the presence of acquired carbapenem-hydrolysing class D ß-lactamases (CHDLs) and clonality. A population structure analysis of IRAB was also conducted, with five molecular typing methods. Three main clusters, each one associated with a specific CHDL, were observed with multilocus sequence typing. Overall, our results suggest a switch in the dominant clone, with sequence type (ST) 92, carrying bla(OXA-23) (63.4%), replacing the closely related ST98, carrying bla(OXA-24/40) (22%). In addition, ST103, an independent lineage, was associated with bla(OXA-58) -carrying isolates (14.6%).
Subject(s)
Acinetobacter Infections/epidemiology , Acinetobacter baumannii/drug effects , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Imipenem/pharmacology , beta-Lactamases/genetics , Acinetobacter Infections/microbiology , Acinetobacter baumannii/classification , Acinetobacter baumannii/enzymology , Acinetobacter baumannii/genetics , Bacterial Typing Techniques , Drug Resistance, Bacterial/genetics , Electrophoresis, Gel, Pulsed-Field , Humans , Microbial Sensitivity Tests , Portugal/epidemiology , Sequence Analysis, DNASubject(s)
Acinetobacter Infections/microbiology , Acinetobacter baumannii/drug effects , Acinetobacter baumannii/enzymology , Anti-Bacterial Agents/pharmacology , Drug Resistance, Multiple, Bacterial , Pancreatitis, Acute Necrotizing/microbiology , beta-Lactamases/biosynthesis , Acinetobacter baumannii/isolation & purification , Adult , Bacterial Proteins/biosynthesis , Female , Humans , Microbial Sensitivity TestsABSTRACT
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.
