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Colonisation and infection due to Enterobacteriaceae producing plasmid-mediated AmpC β-lactamases

Jesús Rodríguez-Baño1, Elisenda Miró, Macarena Villar

  • 1Unidad Clínica de Enfermedades Infecciosas y Microbiología, Hospital Universitario Virgen Macarena, Avda Dr Fedriani 3, 41009 Sevilla, Spain. jesusrb@us.es

The Journal of Infection
|December 6, 2011
PubMed
Abstract

Insights

Plasmid-mediated AmpC β-lactamase (pAmpC)-producing Enterobacteriaceae cause serious infections, particularly in vulnerable patients. High mortality rates in invasive cases may stem from incorrect initial antibiotic treatments.

Area of Science:

  • Microbiology
  • Epidemiology
  • Infectious Diseases

Background:

  • Emerging resistance to extended-spectrum cephalosporins is a growing concern.
  • Plasmid-mediated AmpC β-lactamases (pAmpC) in Enterobacteriaceae contribute significantly to this resistance.
  • Understanding the epidemiology and clinical impact of pAmpC-producing Enterobacteriaceae is crucial.

Purpose of the Study:

  • To investigate the epidemiology of infections caused by pAmpC-producing Enterobacteriaceae.
  • To describe the clinical features and outcomes of these infections.
  • To identify risk factors and potential therapeutic challenges.

Main Methods:

  • A prospective multicenter cohort study was conducted in 7 Spanish hospitals.
  • 140 patients with infection or colonization by pAmpC-producing Enterobacteriaceae were enrolled.
  • pAmpC enzymes were characterized using PCR and sequencing.

Main Results:

  • Escherichia coli was the most common isolate (n=100), followed by Proteus mirabilis and Klebsiella pneumoniae.
  • Most patients (90%) had chronic underlying conditions, and infections were acquired nosocomially (43%), healthcare-associated (41%), or in the community (16%).
  • Bacteraemic patients (19%) received inappropriate empirical therapy (81%) and had a crude mortality rate of 48%. CMY-2 was the most frequent enzyme (70%).

Conclusions:

  • pAmpC-producing Enterobacteriaceae cause significant infections in predisposed patients across various settings.
  • Invasive infections are linked to high mortality, potentially exacerbated by inappropriate empirical therapy.
  • This highlights the need for improved diagnostic and therapeutic strategies for these resistant organisms.

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