GES extended-spectrum β-lactamases in Acinetobacter baumannii isolates in Belgium

Abstract

During a PCR-based surveillance study of β-lactam resistance, 125 multidrug-resistant (MDR) Acinetobacter baumannii isolates were obtained from 18 hospitals in Belgium from January 2008 to December 2009. Nine GES-positive A. baumannii isolates were detected at 6 Belgian hospitals. DNA sequencing of the bla(GES) genes identified GES-11, GES-12, and a novel variant GES-14, which differs from GES-11 by a single amino acid substitution (Gly170Ser). All index isolates were travel associated and originated from patients transferred from Turkey (n = 2), Egypt (n = 2), and Palestinian territories (Gaza) (n = 2). A nosocomial outbreak involving three additional patients occurred in a burn unit at a single hospital. No clonal relatedness could be established between the 6 index isolates by pulsed-field gel electrophoresis (PFGE) analysis. Three different alleles (the plasmid-located bla(GES-11) and bla(GES-12) and a likely chromosomally located novel variant bla(GES-14)) were detected as part of a class 1 integron, also including the aac6'Ib and dfrA7 genes. Restriction analysis of plasmids suggests a common origin for the plasmids bearing bla(GES-11) and bla(GES-12). Cloning of the bla(GES) genes in Escherichia coli identified GES-14 as hydrolyzing imipenem, while GES-12 showed the highest specific activity against ceftazidime. This report highlights the emergence of various bla(GES-like) genes, especially those conferring carbapenem resistance in A. baumannii and its importation in Western Europe from Middle Eastern countries.

FIG. 1.

Dendrogram of PFGE patterns of A. baumannii clinical isolates and reference strains of European clones I, II, and III. RUH0875, RUH0134, and LUH05875 correspond to European clones I, II, and III, respectively (4).

FIG. 2.

Crude plasmid extracts and banding patterns of plasmids pGES-11 and pGES-12 corestricted with HindIII and EcoRI. Lane M, 2 log DNA ladder (0.1 to 10.0 kb); lane 1, pGES-11 (from isolate 9027) extract digested with EcoRI and HindIII; lane 2, pGES-12 (from isolate 9135) extract digested with EcoRI and HindIII; lane 3, undigested pGES-11 crude extract; lane 4, undigested pGES-12 crude extract.