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Oral Transmission of Listeria monocytogenes in Mice via Ingestion of Contaminated Food
08:38

Oral Transmission of Listeria monocytogenes in Mice via Ingestion of Contaminated Food

Published on: May 6, 2013

Emergence and genomic characterization of Listeria monocytogenes causing human listeriosis in Pakistan, 2017-2023

Imran Ahmed1,2, Javaria Ashraf3, Hassan Ghayas3

  • 1Aga Khan University, Karachi, Pakistan. imran.haq@aku.edu.

BMC Microbiology
|May 30, 2026
PubMed
Abstract

Insights

Human listeriosis (Listeria monocytogenes) is emerging in Pakistan. Genomic analysis revealed three clades, with two sequence types (ST1 and ST308) dominating, suggesting potential common sources requiring public health intervention.

Area of Science:

  • Microbiology
  • Genomics
  • Epidemiology

Background:

  • Human listeriosis, a severe foodborne illness caused by Listeria monocytogenes, has limited data from Pakistan.
  • This study investigates the emergence and genomic characteristics of human L. monocytogenes cases in Pakistan from 2017 to 2023.

Purpose of the Study:

  • To report the emergence of human listeriosis in Pakistan.
  • To characterize the genomic features of Listeria monocytogenes isolates from Pakistan.
  • To assess the frequency and geographic distribution of cases.

Main Methods:

  • Identification of L. monocytogenes from clinical specimens using culture and multiplex PCR.
  • Whole genome sequencing of selected isolates.
  • Bioinformatic analyses including MLST, serogroup determination, phylogenetic analysis, and core genome MLST (cgMLST).

Main Results:

  • L. monocytogenes isolation increased significantly from 2017-2023, primarily from bloodstream (n=90) and CNS infections (n=47).
  • Phylogenetic analysis of 24 isolates revealed three clades; the largest clade comprised 22 isolates belonging to clonal complex-1, Serogroup 4b, Lineage-I, with sequence types ST1 (59%) and ST308 (41%).
  • cgMLST indicated close genetic relationships among isolates within ST1 and ST308.

Conclusions:

  • Human listeriosis is an emerging infection in Pakistan, crucial for consideration in empiric therapy.
  • cgMLST findings suggest potential common sources, necessitating identification and robust public health measures for control.
Keywords:
EmergingHuman listeriosisPakistanWhole genome sequencing

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