Trueperella pyogenes

Trueperella pyogenes, previously classified as Arcanobacterium pyogenes, is an opportunistic Gram-positive non-motile, facultatively anaerobic bacterium of the Actinomycetaceae family. T. pyogenes infections occur mainly in cattle, swine, sheep, goats, and rarely in horses or birds. In the United States and Canada, T. pyogenes is an emerging pathogen of deer, which causes intracranial abscessation, keratoconjunctivitis, and foot abscesses.

In cows, T. pyogenes causes infections of the reproductive tract (metritis and endometritis) and the mammary gland, as well as pneumonia and liver abscessation. T. pyogenes is also found as normal biota on the udders of dairy cows. T. pyogenes is a significant cause of summer mastitis, a disease which occurs mainly in cows during the summer, and is associated with pathogen transmission by the insect Hydrotaea irritans. In pigs, T. pyogenes has been associated with pneumonia, pleuritis, endocarditis, osteoarthritis, polyarthritis, mastitis, reproductive tract infections, and septicaemia.

In 2020, T. pyogenes was isolated from the air sacs and trachea of an 18-month-old rooster in a backyard flock in California. The bird had a history of progressive emaciation and had numerous miliary granulomas found throughout his spleen, air sacs, and lungs. He was one of 15 other chickens who was diagnosed with infection with T. pyogenes between 2020 and 2021.

Beta-lactams, tetracyclines, and macrolides are the antibiotics most often used to treat T. pyogenes infections.


  • Order: Actinomycetales
  • Family: Actinomycetaceae
  • Genus: Trueperella


  • cattle
  • pigs
  • sheep
  • goats
  • deer