Streptococcus spp

The genus Streptococcus are gram-positive spherical bacteria which are divided into 49 species and eight subspecies. Streptococcal bacterial are common inhabitants of the intestinal tract of numerous animal species, including poultry and humans. Streptococcus have potential to cause opportunistic infections in poultry. However, the factors that lead to Streptococcus getting into the blood stream and colonizing tissue are unknown.

Streptococcus infection causes the disease called known as streptococcosis in poultry, occurring as an acute septicemia and chronic infections such as salpingitis, peritonitis, fibrinous arthritis, fibrinous pericarditis and perihepatitis, tenosynovitis, osteomyelitis, splenitis, conjunctivitis, hepatitis, necrotic myocarditis, and valvular endocarditis.

Species of Streptococcus known to cause disease in poultry include:
  • S. dysgalactiae : Cultured from broilers with cellulitis, a condition observed on the skin and subcutaneous tissue right before they were slaughtered.
  • S. mutans : A common bacterium in the human oral cavity which has been associated with septicemia and mortality in geese.
  • S. bovis and S. gallolyticus: Were identified from multiple organs, with macroscopic or histopathologic lesions (or both) indicative of septicemia in 24-42% necropsy cases in a study conducted by the CAHFS.
  • S. pluranimalium and S. lutetiensis: Were isolated from 1-2% of necropsy cases in a study by the CAHFS. Splenitis and hepatitis were the most-common lesions observed and these were the organs with the highest isolation rate.
  • S. zooepidemicus: A commensal of the mucous membranes and skin of animals, notably equine, that has been associated with several outbreaks in poultry.
  • S. suis : Four cases were diagnosed in psittacine birds and four others in zebrafinches, bullfinches, canaries and a duck. S. suis is a normal inhabitant of the tonsils of pigs, cattle, dogs, and cats. It is not normally found in poultry.
Incubation periods range from 1 day to several weeks, with 5–21 days being most common.

Treatment: Antibacterial susceptibility should be performed on bacterial isolates in any clinical cases of Streptococcus.



  • Order: Lactobacillales
  • Family: Streptococcaceae
  • Genus: Streptococcus


  • animals
  • humans
  • pigs
  • cattle

Associated Diseases