Molecular characterization of carbapenem-insensitive Acinetobacter baumannii in Egypt

Abstract

The blaADC-, blaTEM-, blaPER-, blaOXA-23-, and blaGES-like genes were found to be the most prevalent types of β-lactamase-encoding gene in A. baumannii collected from Egypt. A high level of carbapenem resistance is mediated by blaOXA-23, blaOXA-24, and blaOXA-58 (minimum inhibitory concentration (MIC) 32 to >256μg/ml), and a low level of carbapenem resistance is mediated by blaGES (MIC 4-16μg/ml) and by up-regulation of ISAba1-OXA-51 (MIC 1-4μg/ml). Class B MBL was not identified to play a role in carbapenem resistance in A. baumannii isolates from Egypt.

Multidrug-resistant Acinetobacter baumannii strains carrying the blaOxA-23 and the blaGES-11 genes in a neonatology center in Tunisia

“…The bla OxA-23 was previously described in the university hospital Sahloul in Tunisia [3] and it was chromosome located. However, numerous other studies showed the plasmid location of the bla OxA-23 gene [6,24].So, a possible transfer of this strain from the Sahloul university hospital to the neonatology center is strongly probable.…”

“…OXA-type carbapenemases have predominated in A. baumannii, especially worldwide outbreaks of OXA-23 [1]. Recently the GES-1-like carbapenemases have also been reported for A. baumannii [9,14,23,24,25].…”

“…Since then, several GES-1 mutants have been detected in A. baumannii, such as GES-12, GES-14, and GES-22 [9,14,22,23,24]. a CLA, Clavulanic acid (4 mg/ml); TZB, Tazobactam (4 mg/ml).…”

“…GES-11 b-lactamase possesses increased activity against aztreonam [14,23]. However the bla GES-11 -carrying transconjugant showed reduced susceptibilities to carbapenems, suggesting the presence of weak hydrolysis of carbapenems by this enzyme potentiated by the efflux overproduction in A. baumannii BM4547 [14,23].So, GES-11 may contribute to play a synergistic role toward resistance to carbapenems in A. baumannii, together with OXA-23 [14].Several studies reported the association between the bla GES and bla OxA-like gene, especially bla GES-11 and bla OxA-23 genes [14,23,24]. To our knowledge, however, carbapenem resistant A. baumannii isolate producing the carbapenem-hydrolyzing oxacillinase OXA-23 in association with the GES-11 class A b-lactamase in Tunisia have not been reported previously.…”

“…Plasmid analysis and AB-PBRT PCR showed that both plasmids (pAb453 and pAB537) were of ca. 90 Kb in size and belonged to the plasmid group Gr6 which has been shown to be highly prevalent in A. baumannii strains and was previously found to be associated with the bla OxA-23 , bla OxA-40 ,,bla OxA-58 CHDL genes and the bla GES-11/ GES-14 genes [2,14,24].…”