Emergence of OXA-48-type carbapenemase-producing Enterobacteriaceae in German hospitals

Area of Science:

• Microbiology
• Molecular Biology
• Infectious Diseases

Background:

• Carbapenem-resistant Enterobacteriaceae (CRE) pose a significant global health threat.
• Carbapenemases, such as OXA-48, are key mechanisms of carbapenem resistance in Enterobacteriaceae.
• Understanding the genetic basis and dissemination of carbapenemase genes is crucial for infection control.

Purpose of the Study:

• To investigate the genetic characteristics and molecular epidemiology of carbapenem-resistant Enterobacteriaceae isolates in German hospitals.
• To identify the types of carbapenemases produced and their genetic location.
• To determine the potential for clonal spread of specific CRE strains.

Main Methods:

• Phenotypic characterization of Enterobacteriaceae isolates for carbapenem resistance.
• Detection and sequencing of carbapenemase genes (blaOXA-48 and variants).
• Plasmid analysis to determine the location of carbapenemase genes.
• Pulsed-field gel electrophoresis (PFGE) for strain typing and epidemiological analysis.

Main Results:

• Nine CRE isolates from eight patients in five German hospitals were analyzed.
• Six isolates harbored the blaOXA-48 gene, and three harbored the blaOXA-162 gene, a point mutant of OXA-48.
• Both carbapenemase genes were located on IncL/M conjugative plasmids, often associated with insertion sequence IS1999.
• PFGE indicated clonal transmission of an OXA-48-producing Klebsiella pneumoniae strain in two hospitals.

Conclusions:

• The study identified OXA-48 and its variant OXA-162 as prevalent carbapenemases in German Enterobacteriaceae isolates.
• The presence of these genes on mobile plasmids, alongside insertion sequence IS1999, facilitates their spread.
• Clonal spread of specific CRE strains, like the identified K. pneumoniae, contributes to hospital-acquired infections.