Recurrent coliform mastitis in the dairy cow

Area of Science:

• Veterinary Medicine
• Microbiology
• Animal Science

Background:

• Bovine mastitis is a significant concern in dairy farming, impacting animal health and milk production.
• Escherichia coli (E. coli) is a common causative agent of mastitis, often leading to acute inflammation.
• Understanding the persistence and recurrence patterns of E. coli infections is crucial for effective management.

Purpose of the Study:

• To investigate the long-term course and characteristics of experimental E. coli mastitis in dairy cows.
• To determine the localization of bacteria during remission periods.
• To evaluate the efficacy of antibiotic therapy in resolving persistent E. coli mastitis.

Main Methods:

• Daily monitoring of milk for bacterial counts and neutrophil levels over 120 days.
• Experimental induction of E. coli mastitis in a cohort of dairy cows.
• Isolation and serotyping of bacteria during acute and remission phases.
• In vitro antibiotic susceptibility testing and in vivo therapeutic trials.

Main Results:

• Five out of 28 experimentally infected cows developed long-continued and recurring mastitis.
• Recurring episodes involved acute inflammation and pyrexia, with consistent serotypes of E. coli isolated.
• Periods of remission without detectable bacteria in milk suggested intracellular bacterial localization within mammary tissue.
• One antibiotic effective in vitro failed to resolve the infection in vivo, while another proved successful.

Conclusions:

• E. coli can establish persistent, recurring infections within bovine mammary gland tissue, not just the cistern.
• Intracellular bacterial persistence complicates treatment and necessitates targeted therapeutic strategies.
• Effective antibiotic selection is critical, as in vitro efficacy does not always predict in vivo success for mastitis treatment.