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Updated: Jan 7, 2026
Characterization of a Pathogenic Escherichia coli Strain Derived from Oreochromis spp. Farms Using Whole-Genome Sequencing
Published on: December 23, 2022
Genome organization, virulence genes, and temperature-dependent motility of an emerging pathogen, Escherichia
Pelumi M Oladipo1,2, Ali M Jomaa1, Jeffrey H Withey2
1Department of Physiology, Wayne State University School of Medicine, Detroit, MI, United States.
Introduction:
Escherichia marmotae is one of the Escherichia cryptic clades that were first isolated from animal feces and environmental waters and has recently emerged as an organism of concern due to its presence in human infections. Although E. marmotae cannot be distinguished from E. coli by standard clinical tests, its 10% pairwise genomic difference from E. coli led us to investigate other phenotypic differences that may be present.
Methods:
Bioinformatic software was used to identify the E. marmotae pan-genome, antimicrobial and virulence genes, and sequences of genes for motility, biofilm formation, and other phenotypic characteristics. Environmental and clinical isolates of E. marmotae were analyzed for antimicrobial sensitivity, and for temperature effects on motility, growth, and biofilm formation, in comparison to E. coli. RT-PCR analyzed associated changes in gene expression.
Results:
The E. marmotae genome consists of >75% core genes, and has many accessory genes, including plasmids and antimicrobial resistance genes. E. marmotae is resistant to erythromycin. E. marmotae had all genes needed for complete flagellar gene assembly, and phenotypically was motile at 28°C, and much less motile at 37°C. More biofilm formation was observed at 28°C than at 37°C. The expression of motility genes motA and fliA decreased at 37°C in E. marmotae compared to E. coli.
Conclusion:
These temperature-sensitive traits may support environmental persistence and adaptations that may facilitate E. marmotae to cause human disease.
Insights
Escherichia marmotae, a bacterium found in animals and the environment, shows temperature-sensitive motility and biofilm formation. These traits may help it persist in the environment and cause human infections.
Area of Science:
- Microbiology
- Genomics
- Infectious Diseases
Background:
- Escherichia marmotae is a cryptic species within the Escherichia genus, initially isolated from animal feces and water.
- It has recently gained attention due to its association with human infections.
- Distinguishing E. marmotae from E. coli using standard clinical methods is challenging despite genomic differences.
Purpose of the Study:
- To investigate phenotypic differences between E. marmotae and E. coli.
- To identify antimicrobial resistance and virulence genes in E. marmotae.
- To analyze temperature-dependent traits like motility and biofilm formation.
Main Methods:
- Bioinformatic analysis of the E. marmotae pan-genome.
- Antimicrobial sensitivity testing of environmental and clinical isolates.
- Comparative analysis of motility, growth, and biofilm formation at different temperatures (28°C vs. 37°C).
- RT-PCR to assess gene expression changes.
Main Results:
- E. marmotae possesses core and accessory genes, including those for antimicrobial resistance (e.g., erythromycin resistance).
- It exhibits temperature-sensitive motility and biofilm formation, with reduced motility and biofilm at 37°C compared to 28°C.
- Expression of motility genes (motA, fliA) decreased at 37°C.
Conclusions:
- Temperature-sensitive traits in E. marmotae may contribute to its environmental persistence.
- These adaptations could facilitate its ability to cause human disease.
- Further research is needed to understand the clinical implications of E. marmotae infections.
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