Carbapenemase-producing Pseudomonas aeruginosafrom central Greece: molecular epidemiology and genetic analysis of class I integrons

Abstract

BackgroundMultidrug-resistant Pseudomonas aeruginosa is a serious challenge for antimicrobial therapy of nosocomial infections, as it possesses several mechanisms of antimicrobial resistance. In Central Greece, a sudden increase of infections caused by carbapenem-resistant P. aeruginosa was observed during 2011, indicating the need for further analysis.MethodsFive-hundred and sixty-eight P. aeruginosa isolates were collected consecutively during an 8-month period in 2011 from inpatients treated in three hospitals in the Thessaly region (1,000,000 habitants) of Greece. Carbapenem-resistant P. aeruginosa (n = 284) were characterized by antimicrobial susceptibility testing and β-lactamase content, and the genetic relatedness of carbapenemase-producing isolates was assessed by BOX-PCR, multilocus sequence typing, and eBURST analysis. Mapping of the class I integrons of Verona integron-encoded metallo-β-lactamase (VIM)-carrying isolates was also performed, and clinical data of the VIM producers were reviewed.ResultsEighty (14.1%) out of the 568 P. aeruginosa isolates recovered from clinical specimens were VIM producers. Multilocus sequence typing revealed high prevalence of the international clones ST111 and ST235 among blaVIM-2- and blaVIM-4-positive isolates, respectively. blaVIM-17 was identified in an isolate of a novel sequence type (ST1457). blaVIM gene cassettes were carried by five distinct class I integrons, including two novel ones.ConclusionsSince the first report of VIM-producing P. aeruginosa in 2000, this microorganism still remains among the most prevalent multidrug resistant pathogens in Greece. The spread of VIM-producers belonging to the most common international clones (ST111 and ST235), the spread of integrons of divergent structures, and the emergence of novel integrons underscore their ongoing evolution.

Molecular identification of tigecycline- and colistin-resistant carbapenemase-producing Acinetobacter baumannii from a Greek hospital from 2011 to 2013

“…In Greece, an increase in carbapenem resistance was observed from 2005 onwards accompanied by a shift of the incidence of the predominant STs among bla OXA-58 producers, whereas bla OXA-23 producers emerged and replaced the previously predominant bla OXA-58 -positive A. baumannii strains during 2011 (Liakopoulos et al, 2012). The emergence of colistin-resistant carbapenemase-producing A. baumannii has also been reported in other studies (Miyakis et al, 2011;Samonis et al, 2010).…”

“…It is noteworthy that seven colistin-resistant isolates carried both bla OXA-23 and bla OXA-58 genes (Table 1). Both bla OXA-23 and bla OXA-58 genes have been identified previously in an A. baumannii isolate in Greece (Liakopoulos et al, 2012). A cluster of 21 isolates comprised tigecycline-resistant bla OXA-23 producers and displayed a single antimicrobial resistance pattern.…”

“…Of the seven bla OXA-23 producers of 3LST ST101, five isolates were tigecycline resistant and two were colistin resistant. The 3LST ST101 (ompA-csuE-bla OXA-51 -like allelic profile: 1-1-1; ST group 1) corresponds to the international clone II, which has previously been associated with divergent bla OXA-23 -producing strains in several countries worldwide, including Greece (Liakopoulos et al, 2012;Turton et al, 2007;Zarrilli et al, 2013); thus, the acquisition of tigecycline and colistin resistance in strains of this clone is worrying for the therapeutic options and infection control policies for MDR A. baumannii.…”

Carbapenemase Detection among Carbapenem-Resistant Glucose-Nonfermenting Gram-Negative Bacilli

“…Unlike the data from carbapenem-resistant Enterobacteriaceae (CRE) (6), the proportions of carbapenem-resistant glucose-nonfermenting isolates due to carbapenemases are unknown, according to U.S. estimates, but likely differ between P. aeruginosa and A. baumannii. Although carbapenem resistance among P. aeruginosa strains is predominantly mediated by non-carbapenemase mechanisms, including the loss of OprD porin expression (most common) and/or upregulation of MexAB-OprM efflux pumps (7,8), increasing numbers of carbapenemase-producing P. aeruginosa isolates are being reported both in the United States and globally (9)(10)(11)(12)(13)(14). Similarly to what others have reported (8), the majority of the 14 carbapenemase-producing P. aeruginosa isolates included in our cohort belonged to Ambler class B MBLs, primarily VIM and IMP carbapenemases (8).…”

Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Meropenem Hydrolysis Assay with NH 4 HCO 3 , a Reliable Tool for Direct Detection of Carbapenemase Activity

“…The MICs of ceftazidime and meropenem were determined by the broth dilution method (22). The group included 113 isolates producing KPC-(n ϭ 21), VIM-(n ϭ 44), NDM-(n ϭ 24), IMP-(n ϭ 4), and OXA-48-type (n ϭ 19) carbapenemases and one isolate coproducing VIM and IMP metallo-␤-lactamases (23)(24)(25)(26)(27)(28)(29). The remaining 48 isolates were non-carbapenemase producers (Table 1) (21,30).…”