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Prolonged bacteraemia caused by VIM-1 metallo-beta-lactamase-producing Proteus mirabilis: first report from Italy

M Falcone1, M Perilli, M L Mezzatesta

  • 1Dipartimento di Medicina Clinica, Policlinico Umberto I, University of Rome La Sapienza, Rome, Italy.

Clinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases
|July 24, 2009
PubMed

Insights

A Proteus mirabilis infection resistant to meropenem, despite in vitro susceptibility, highlights the emergence of metallo-beta-lactamase in Italy. The patient recovered with cefepime and amikacin treatment.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Genetics

Background:

  • Post-operative mediastinitis can lead to persistent bloodstream infections.
  • Proteus mirabilis is an opportunistic pathogen.
  • Integrons are genetic elements that confer antibiotic resistance.

Observation:

  • A clinical isolate of Proteus mirabilis exhibited persistent bacteremia.
  • The isolate possessed two class 1 integrons with bla(VIM-1) and aadA2 gene cassettes.
  • These resistance genes were located on both chromosomal and plasmid DNA.

Findings:

  • The Proteus mirabilis isolate showed in vitro susceptibility to carbapenems.
  • Meropenem therapy was ineffective in treating the patient's persistent bacteremia.
  • The patient responded successfully to cefepime plus amikacin.

Implications:

  • This is the first report of metallo-beta-lactamase (VIM-1) production in a clinical Proteus mirabilis isolate in Italy.
  • The findings underscore the importance of monitoring emerging antibiotic resistance mechanisms.
  • Treatment strategies may need to be adjusted for infections caused by metallo-beta-lactamase-producing Enterobacterales.

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