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Virulence genes of Escherichia coli strains isolated from mastitic milk

A Bean1, J Williamson, R T Cursons

  • 1Molecular Genetics Laboratory, Department of Biological Sciences, University of Waikato, Hillcrest Road, Hamilton 2001, New Zealand.

Journal of Veterinary Medicine. B, Infectious Diseases and Veterinary Public Health
|October 2, 2004
PubMed

Insights

Escherichia coli isolates from cows with mastitis were analyzed for virulence genes. While some isolates carried toxin genes like stx1, their presence did not correlate with disease severity in infected cows.

Area of Science:

  • Veterinary Microbiology
  • Bacterial Pathogenesis
  • Animal Health

Background:

  • Bovine mastitis is a significant concern in dairy farming.
  • Escherichia coli (E. coli) is a common cause of environmental mastitis.
  • Virulence factors of E. coli can influence disease outcomes.

Purpose of the Study:

  • To identify E. coli virulence genes in isolates from cows with clinical mastitis.
  • To determine the prevalence of specific E. coli toxin genes.
  • To investigate the correlation between E. coli virulence genes and disease severity.

Main Methods:

  • Isolation of E. coli from milk of symptomatic cows.
  • DNA amplification assays to screen for virulence genes (cnf1, cnf2, eaeA, eagg, einv, ltx1, stx1, stx2, vt2e).
  • Correlation analysis between gene presence and clinical condition.

Main Results:

  • Eighty E. coli isolates were obtained from 34 cows over 17 months.
  • Thirty isolates (37.5%) possessed identified toxin genes.
  • The most prevalent gene was stx1 (31%), followed by cnf2 (7.5%), vt2e (6.25%), and eaeA (4%).

Conclusions:

  • The prevalence of specific E. coli virulence genes was determined in bovine mastitis isolates.
  • The presence of these toxin genes did not significantly impact the clinical presentation or severity of mastitis in the studied cows.
  • Further research may be needed to understand the full spectrum of virulence factors and their role in bovine E. coli infections.

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