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Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
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Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance

Published on: May 2, 2018

Spread of multidrug-resistant Proteus mirabilis isolates producing an AmpC-type beta-lactamase: epidemiology and

Francesco Luzzaro1, Gioconda Brigante, Marco Maria D'Andrea

  • 1Laboratory of Medical Microbiology, Ospedale di Circolo, University of Insubria, Varese, Italy.

International Journal of Antimicrobial Agents
|December 20, 2008
PubMed

Insights

A rise in Proteus mirabilis infections resistant to AmpC-type beta-lactamases (CBLs) was observed. These multidrug-resistant strains, primarily causing urinary tract infections, require new detection methods for effective treatment.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Antimicrobial Resistance

Background:

  • An increase in acquired AmpC-type beta-lactamase (CBL)-producing Proteus mirabilis strains was noted in Varese, Italy.
  • This spread of multidrug-resistant bacteria poses a significant public health challenge.

Purpose of the Study:

  • To investigate the epidemiology and treatment outcomes of infections caused by CBL-positive P. mirabilis.
  • To characterize the resistance determinants and clonal relatedness of these isolates.

Main Methods:

  • Analysis of 2070 P. mirabilis isolates collected between 2004-2006.
  • Identification of resistance genes (ESBLs, CBLs) using gene amplification and direct sequencing.
  • Evaluation of clonal relatedness via macrorestriction analysis.

Main Results:

  • Prevalence of CBL-positive P. mirabilis increased from 0.3% to 4.6% between 2004 and 2006.
  • All CBL-positive isolates were multidrug-resistant, carried the CMY-16 determinant, and were genetically related.
  • Urinary tract infections were the most common clinical manifestation.

Conclusions:

  • This study reports the first rapid spread of CBL-positive P. mirabilis with high antimicrobial resistance.
  • Amikacin and carbapenems showed consistent efficacy, while piperacillin/tazobactam had a partial response rate.
  • Development of practical CBL detection methods is crucial for managing these infections.

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