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Distribution and characterization of Listeria monocytogenes clinical isolates in Portugal, 1994-2007

G Almeida1, A Morvan, R Magalhães

  • 1Centro de Biotecnologia e Química Fina, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr António Bernardino de Almeida, 4200-072 Porto, Portugal.

European Journal of Clinical Microbiology & Infectious Diseases : Official Publication of the European Society of Clinical Microbiology
|June 22, 2010
PubMed

Insights

This study characterized Listeria monocytogenes from Portuguese listeriosis cases using biotyping, PCR, and pulsed-field gel electrophoresis (PFGE). Findings reveal recurrent and geographically distributed strains, aiding in outbreak investigations.

Area of Science:

  • Microbiology
  • Epidemiology
  • Food Safety

Background:

  • Listeriosis cases caused by Listeria monocytogenes have globally increased.
  • Characterization of clinical isolates is crucial for understanding transmission and guiding public health interventions.

Purpose of the Study:

  • To genetically and biochemically characterize 95 Listeria monocytogenes isolates from Portuguese human listeriosis cases.
  • To establish a comprehensive pulsotype database for Portuguese clinical strains.

Main Methods:

  • Isolates were analyzed using biotyping (heavy metal sensitivity), Polymerase Chain Reaction (PCR) grouping, and Pulsed-Field Gel Electrophoresis (PFGE) with AscI and ApaI enzymes.
  • Data were combined to identify distinct PCR groups, biotypes, and PFGE types.

Main Results:

  • Isolates belonged to PCR groups IVb (71.6%), IIb (17.9%), and IIa (10.5%).
  • Four distinct biotypes based on arsenic and cadmium sensitivity were identified.
  • Pulsed-field gel electrophoresis (PFGE) revealed 58 types, with five main strain sets.
  • Recurrent pulsotypes, some linked to French outbreaks, were identified, alongside geographically widespread and restricted strains.

Conclusions:

  • The study established a foundational database of Portuguese Listeria monocytogenes pulsotypes.
  • Genetic and geographic data provide insights into strain distribution and potential for recurrent outbreaks.
  • Characterization aids in epidemiological surveillance and control of listeriosis in Portugal.

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