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Carbapenemase-producing Pseudomonas aeruginosa from central Greece: molecular epidemiology and genetic analysis of
Apostolos Liakopoulos, Angeliki Mavroidi, Efstathios A Katsifas
1Department of Microbiology, University Hospital of Larissa, Larissa, Greece. petinaki@med.uth.gr.
Background:
Multidrug-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.
Methods:
Five-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.
Results:
Eighty (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.
Conclusions:
Since 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.
Insights
Multidrug-resistant Pseudomonas aeruginosa, particularly carbapenem-resistant strains, remains a significant threat in Greek hospitals. Ongoing evolution of resistance mechanisms, including integrons and international clones, necessitates continued surveillance.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Multidrug-resistant Pseudomonas aeruginosa poses a significant challenge in treating hospital-acquired infections.
- A notable increase in carbapenem-resistant P. aeruginosa infections was observed in Central Greece in 2011.
- Analysis was needed to understand the epidemiology and resistance mechanisms in this region.
Purpose of the Study:
- To investigate the prevalence and characteristics of carbapenem-resistant Pseudomonas aeruginosa in Greece.
- To identify the resistance mechanisms, particularly carbapenemases like Verona integron-encoded metallo-β-lactamase (VIM).
- To assess the genetic relatedness and clonal dissemination of VIM-producing P. aeruginosa.
Main Methods:
- Collected 568 P. aeruginosa isolates from inpatients in three Greek hospitals over 8 months in 2011.
- Characterized 284 carbapenem-resistant isolates using antimicrobial susceptibility testing and β-lactamase analysis.
- Employed BOX-PCR, multilocus sequence typing (MLST), and eBURST for genetic relatedness and integron mapping.
Main Results:
- Eighty (14.1%) isolates were identified as VIM producers.
- MLST revealed high prevalence of international clones ST111 and ST235 among blaVIM-2 and blaVIM-4 positive isolates, respectively.
- Two novel class I integrons were identified alongside previously known structures, with blaVIM-17 found in a novel ST1457.
Conclusions:
- VIM-producing P. aeruginosa remains a prevalent multidrug-resistant pathogen in Greece.
- The study highlights the ongoing spread of VIM-producers within common international clones (ST111, ST235).
- The emergence of novel integrons and divergent structures indicates continuous evolution of resistance in P. aeruginosa.
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