ISSN 2398-2942      

Streptococcus spp





  • Phylum: Firmicutes
  • Class: Bacilli
  • Order: Lactobacillales
  • FamilyStreptococceae
  • GenusStreptococcus


  • Gk: streptos - twisted; kokkos - grain, berry, seed.

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Clinical Effects



  • Environmental streptococci are rarely associated with disease.
  • Many animal-associated streptococci are commensals on mucosal surfaces of respiratory, GI or urogenital systems.
  • Streptococcus canis Streptococcus canis , is a host-adapted, beta-hemolytic species.


  • Cells divide by binary fission to produce pairs or chains.


  • Most streptococcal infections are cause by endogenous flora.
  • Horizontal transmission may occur by inhalation, ingestion, congenital or sexual contact, and contact with contaminated fomites.
  • Zoonotic transmission is rare, eg dog to man (S.equi subsp zooepidemicus Streptococcus equi , horse to dog (S.equi subsp equi), man to dog (S.pyogenes).

Pathological effects

  • Host defense depends on phagocytosis.
  • Capsules of some species antiphagocytic.
  • Antibodies may be raised against M protein or other surface antigens.
  • Recovered animals have short-term resistance to reinfection.
  • Immunity is serotype-specific.
  • Most streptococci are opportunistic pathogens.
  • Beta-hemolytic species more frequently associated with acute disease.
  • Streptococci are pyogenic bacteria that elicit suppurative host inflammatory responses.
  • Adhesins mediate attachment.
  • Extracellular products may include streptolysin O and S, hyaluronidase, DNAase, protease, streptokinase, streptococcal pyrogenic exotoxins.
  • Virulence mechanisms are often unknown.

Other Host Effects


  • Disease manifestations include: abscesses (cutaneous, lymphatic, oropharyngeal, etc), neonatal septicemia, endocarditis, pneumonia, necrotizing fascilitis Skin: necrotizing fasciitis , toxic shock.


  • Co-pathogens found in some infections.


Control via animal

  • Isolate and treat clinically affected animals.
  • Isolate and treat exposed animals (to control outbreak).
  • Quarantine until 2 weeks after resolution of signs (for contagious species).
  • General health maintenance including dental health and nutrition.

Control via chemotherapies

  • Usually susceptible to penicillin Benzylpenicillin , cephalosporins, and potentiated sulfonamides, macrolides, chloramphenicol Chloramphenicol.
  • Often resistant to aminoglycosides and tetracyclines.
  • Treatment only effective if started early following onset of clinical signs.
  • Endo and ecto parasite control.

Control via environment

  • Clean, disinfect and dry all environmental surfaces that were exposed to infected dogs.
  • Most disinfectants, at recommended use dilutions and contact times, effectively kill pathogenic streptococci.
  • Use of separate protective clothing (glove, mask, footwear, etc) when examining infected animals.


  • No streptococcal vaccines available for use in dogs.
  • Maintain recommended vaccinations against other agents.

Other countermeasures

  • Isolate newly admitted dogs from clinically affected and exposed dogs.
  • Prophylactic treatment of newly admitted dogs may be indicated in some circumstances.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Abbott Y, Acke E, Khan S (2010) Zoonotic transmission of Streptococcus equi subsp. Zooepidemicus from a dog to a handler. J Med Microbiol 59 (1), 120-123 PubMed.
  • Pesavento P A, Hurley K F, Bannash M J et al (2008) A clonal outbreak of acute fatal hemorrhagic pneumonia in intensively housed (shelter) dogs caused by Streptococcus equi subsp. zooepidemicus. Vet Pathol 45 (1), 51-53 PubMed.
  • Kim M K, Jee H, Shin S W et al (2007) Outbreak and control of haemorrhagic pneumonia due to Streptococcus equi subspecies zooepidemicus in dogs. Vet Rec 161 (15), 528-530 PubMed.
  • Ladlow J, Scase T & Waller A (2006) Canine strangles case reveals a new host susceptible to infection with Streptococcus equi. J Clin Microbiol 44 (7), 2664-2665 PubMed.
  • Vela A I, Falsen E, Simarro I et al (2006) Neonatal mortality in puppies due to bacteremia by Streptococcus dysgalactiae subsp. dysgalactiae. J Clin Microbiol 44 (2) 666-668 PubMed.
  • DeWinter L M & Prescott J F (1999) Relatedness of Streptococcus canis from canine streptococcal toxic shock syndrome and necrotizing fasciitis. Can J Vet Res 63 (2), 90-95 PubMed.
  • Falck G (1997) Group A streptococci in household pets eyes--a source of infection in humans? Scand J Infect Dis 29 (5), 469-471 PubMed.
  • Messier S, Daminet S & Lemarchand T (1995) Streptococcus agalactiae endocarditis with embolization in a dog. Can Vet J 36 (11), 703-704 PubMed.
  • Ramos-Vara J A, Briones V, Segalés J et al (1994) Concurrent infection with Streptococcus equisimilis and Leishmania in a dog. J Vet Diagn Invest (3), 371-375 PubMed.

Other sources of information

  • Hirsh D C & Biberstein E L (2004) Streptococcus and Enterococcus. In: Hirsh DC, MacLachlan N J & Walker R L (eds) Veterinary Microbiology, 2nd edn, Blackwell Publishing, Ames, IA, USA, pp 159-167.

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