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Author Spotlight: Advancements in Understanding and Combatting Shigella Infections
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Molecular Differentiation of Shigella Spp. from Enteroinvasive E. Coli

I Løbersli1, A L Wester1, Å Kristiansen1

  • 1Department of Foodborne Infections, The Norwegian Institute of Public Health , Oslo, Norway.

European Journal of Microbiology & Immunology
|October 22, 2016
PubMed

Insights

A new real-time PCR assay accurately differentiates Shigella spp. from enteroinvasive Escherichia coli (EIEC), especially the difficult-to-classify EIEC O nontypable strains. This molecular method offers a fast and reliable diagnostic tool for bacterial identification.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Infectious Diseases

Background:

  • Accurate differentiation between Shigella spp. and enteroinvasive Escherichia coli (EIEC) is crucial for public health and clinical management.
  • Traditional methods can be time-consuming and may not reliably distinguish between closely related strains.
  • The EIEC O nontypable (ONT) group presents a particular challenge for accurate classification.

Purpose of the Study:

  • To evaluate the efficacy of a real-time PCR assay targeting the lacY and ipaH genes for differentiating Shigella spp. from EIEC.
  • To compare the real-time PCR results with multiple-locus variable-number tandem repeat analysis (MLVA) for enhanced accuracy.
  • To assess the assay's performance on phenotypically classified isolates, including the challenging EIEC ONT group.

Main Methods:

  • A real-time PCR assay was developed and applied to 121 bacterial isolates.
  • The assay amplified genes encoding lactose permease (lacY) and invasion plasmid antigen H (ipaH).
  • Results were compared against generic E. coli and Shigella MLVA data.

Main Results:

  • The real-time PCR correctly identified Shigella spp. (lacY negative) and EIEC O121/O124 (lacY positive).
  • A majority of EIEC ONT isolates (89.4%) were classified as Shigella (lacY negative) by PCR, supported by MLVA data.
  • Overall concordance between real-time PCR and MLVA was high (94.7%).
  • The assay showed limitations in classifying the EIEC O164 group.

Conclusions:

  • The real-time PCR assay is a fast and accurate method for differentiating Shigella spp. from EIEC, with notable utility for the EIEC ONT group.
  • The assay's performance was largely substantiated by MLVA, indicating its reliability.
  • The real-time PCR assay is a pragmatic molecular tool for routine diagnostics, despite limitations with specific EIEC serotypes like O164.
Keywords:
EIECMLVAShigellamolecular differentiationreal-time PCR

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