[Isolation of a specific agglutinating serum K 99]

Area of Science:

• Veterinary Microbiology
• Bacteriology
• Immunology

Background:

• Escherichia coli (E. coli) is a common cause of calf enteritis.
• The K 99 antigen is a known virulence factor in E. coli.
• Understanding the prevalence and characteristics of K 99 is important for diagnosing and controlling calf diarrhea.

Purpose of the Study:

• To produce specific K 99 antiserum.
• To determine the presence and prevalence of the K 99 antigen in E. coli strains isolated from calves.
• To investigate the optimal production temperature and thermal stability of the K 99 antigen.

Main Methods:

• Production of a specific agglutinative and absorbed K 99 antiserum.
• Testing of 272 E. coli strains isolated from calves for the presence of K 99 antigen using the produced antiserum.
• Differentiation of E. coli strains into enteropathogenic and non-enteropathogenic groups.
• Incubation of E. coli cultures at different temperatures (37°C and 18°C) to assess antigen production and stability.

Main Results:

• The K 99 antigen was detected in 46 out of 272 (16.9%) E. coli strains isolated from calves.
• A significantly higher proportion of enteropathogenic E. coli strains (95.3%) harbored the K 99 antigen compared to non-enteropathogenic strains (2.1%).
• The K 99 antigen is produced optimally at 37°C and not at 18°C, indicating temperature-dependent production.
• The K 99 antigen was found to be unstable with respect to temperature.

Conclusions:

• The K 99 antigen is frequently associated with enteropathogenic E. coli strains in calves.
• The findings highlight the importance of the K 99 antigen in calf enteritis.
• Temperature plays a critical role in the production and stability of the K 99 antigen.