Increasing prevalence and diversity of metallo-beta-lactamases in Pseudomonas spp., Acinetobacter spp., and...

Area of Science:

• Microbiology
• Antimicrobial Resistance
• Molecular Epidemiology

Background:

• Imipenem is a critical antibiotic for treating serious bacterial infections.
• The emergence of imipenem-nonsusceptible bacteria poses a significant public health threat.
• Metallo-beta-lactamases (MBLs) are enzymes that confer resistance to carbapenem antibiotics, including imipenem.

Purpose of the Study:

• To investigate the prevalence of acquired metallo-beta-lactamase genes in imipenem-nonsusceptible Gram-negative bacteria.
• To identify the specific types of MBL genes circulating in clinical isolates.
• To determine the distribution of these genes across different bacterial species.

Main Methods:

• Retrospective analysis of bacterial isolates collected between 2003 and 2004 from a Korean hospital.
• Phenotypic testing to identify imipenem-nonsusceptible isolates.
• Molecular methods, such as PCR and sequencing, to detect and characterize acquired metallo-beta-lactamase genes.

Main Results:

• Acquired metallo-beta-lactamase genes were detected in 6.2% of Pseudomonas aeruginosa, 95.4% of other Pseudomonas species, and 26.5% of Acinetobacter species.
• bla(VIM-2)-like genes were the most prevalent MBL genes identified.
• These genes were also found in Enterobacteriaceae, including Klebsiella pneumoniae.

Conclusions:

• Metallo-beta-lactamase genes are widespread among imipenem-nonsusceptible Pseudomonas and Acinetobacter species in South Korea.
• The high prevalence of bla(VIM-2)-like genes underscores their importance in carbapenem resistance.
• The detection in Enterobacteriaceae suggests potential for interspecies transmission and broader dissemination of carbapenem resistance.