Molecular Characterization of OXA-198 Carbapenemase-Producing Pseudomonas aeruginosa Clinical Isolates

Area of Science:

• Microbiology
• Genetics
• Infectious Diseases

Background:

• Carbapenemase-producing bacteria, particularly Pseudomonadaceae, are a significant global health threat.
• Mechanisms of carbapenem resistance are diverse and vary by bacterial species and region.
• OXA-198 is a plasmid-encoded class D beta-lactamase previously identified in Pseudomonas aeruginosa.

Purpose of the Study:

• To investigate the molecular basis of carbapenem resistance in newly identified OXA-198-producing Pseudomonas aeruginosa isolates.
• To characterize the plasmid carrying the blaOXA-198 gene and the genetic relatedness of the isolates.
• To report the first description of a hospital-associated cluster of OXA-198-producing Pseudomonas aeruginosa.

Main Methods:

• Minimum Inhibitory Concentration (MIC) determination for antibiotic susceptibility testing.
• Whole-genome sequencing (WGS) to identify resistance genes and genetic variations.
• Polymerase Chain Reaction (PCR) analysis to confirm genetic organization.
• Plasmid characterization, including size and type.
• Multilocus Sequence Typing (MLST) to determine isolate relatedness.

Main Results:

• Four OXA-198-producing Pseudomonas aeruginosa isolates were detected in a Belgian hospital.
• The blaOXA-198 gene was located on a class 1 integron within a ~49-kb IncP-type plasmid (proposed as IncP-11).
• All four isolates harbored the same IncP-11 plasmid and belonged to Multilocus Sequence Type 446 (ST446).
• Single-nucleotide polymorphism (SNP) analysis indicated minimal genetic divergence among the isolates.

Conclusions:

• The study elucidates the genetic structure of the ~49-kb plasmid carrying the blaOXA-198 gene.
• It confirms a hospital-associated cluster of ST446 Pseudomonas aeruginosa isolates producing OXA-198.
• This highlights the importance of ongoing surveillance for carbapenem resistance mechanisms in healthcare settings.