Long-term evolution of a nosocomial outbreak of Pseudomonas aeruginosa producing VIM-2 metallo-enzyme

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Metallo-beta-lactamase (MBL)-producing Pseudomonas aeruginosa outbreaks pose significant treatment challenges.
• The VIM-2 MBL-producing strain emerged in a French hospital's haematology ward from 1996 to 2004.

Purpose of the Study:

• To characterize the VIM-2 MBL-producing Pseudomonas aeruginosa outbreak.
• To identify antimicrobial resistance patterns and potential treatment options.

Main Methods:

• Pulsed-field gel electrophoresis (PFGE) was used to analyze bacterial isolates.
• Antimicrobial susceptibility testing was performed against various drug classes.
• The genetic location of the bla(VIM-2) gene was investigated.

Main Results:

• Fifty-nine patients were identified as carriers, with 14 infected, primarily with urinary tract infections and pneumonia.
• Isolates exhibited resistance to beta-lactams, aminoglycosides, fluoroquinolones, fosfomycin, and rifampicin, but remained susceptible to colistin.
• The bla(VIM-2) gene was found within a novel class 1 integron, not on a plasmid.

Conclusions:

• The VIM-2 MBL-producing Pseudomonas aeruginosa strains present a significant antimicrobial resistance threat.
• Piperacillin-tazobactam and aztreonam may be effective therapeutic choices for MBL-producing strain infections in the absence of established guidelines.