Difference between revisions of "Category:Streptococcus species"

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*Haemolytic streptococci of Lancefield group C are common inhabitants of the equine nasopharynx  
 
*Haemolytic streptococci of Lancefield group C are common inhabitants of the equine nasopharynx  
 
*''Streptococcus zooepidemicus'' and ''S. equisimilis'' are usually non-pathogenic
 
*''Streptococcus zooepidemicus'' and ''S. equisimilis'' are usually non-pathogenic
*Involved in [[Peritoneal Cavity Inflammatory - Pathology#In pigs|peritonitis in pigs]],  [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]], [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]], [[Stomatitis|catarrhal stomatitis]]
+
*Involved in [[Peritonitis - Pathology#In pigs|peritonitis in pigs]],  [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]], [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]], [[Stomatitis|catarrhal stomatitis]]
 
*In infectious [[Joints Inflammatory - Pathology#In Sheep|arthritis of sheep]], [[Joints Inflammatory - Pathology#In Cattle|arthritis in calves]], [[Joints Inflammatory - Pathology#In Horses|arthritis in horses]] and [[Joints Inflammatory - Pathology#In Pigs|arthritis in pigs]]
 
*In infectious [[Joints Inflammatory - Pathology#In Sheep|arthritis of sheep]], [[Joints Inflammatory - Pathology#In Cattle|arthritis in calves]], [[Joints Inflammatory - Pathology#In Horses|arthritis in horses]] and [[Joints Inflammatory - Pathology#In Pigs|arthritis in pigs]]
 
*Often commensals on mucous membranes of upper respiratory and lower urogenital tract
 
*Often commensals on mucous membranes of upper respiratory and lower urogenital tract

Revision as of 13:31, 10 June 2010


Overview

  • Cause suppurative infections in many different animals
  • Cause abscess formation and septicaemia
  • Cause mastitis, metritis, polyarthritis, meningitis
  • Primary or secondary infections following viral infection
  • Neonatal septicaemia related to maternal genital tract infection
  • Haemolytic streptococci of Lancefield group C are common inhabitants of the equine nasopharynx
  • Streptococcus zooepidemicus and S. equisimilis are usually non-pathogenic
  • Involved in peritonitis in pigs, pyothorax, osteomyelitis, catarrhal stomatitis
  • In infectious arthritis of sheep, arthritis in calves, arthritis in horses and arthritis in pigs
  • Often commensals on mucous membranes of upper respiratory and lower urogenital tract
  • Opportunistic infections


Characteristics

  • Gram positive cocci forming chains
  • Catalase negative, facultative anaerobes
  • Fastitidious - require enriched media such as blood or serum
  • Small haemolytic, translucent colonies, some mucoid
  • Catalase negative
  • Susceptible to desiccation


Identification

  • Beta haemolysis (complete with clear zones surrounding colonies)
  • Alpha haemolysis (partial with green zones surrounding colonies)
  • Lancefield grouping - serology based on group-specific polysaccharide in cell wall
  • Biochemical testing


Diagnosis

  • Swabs of pus or exudate cultured on blood agar and MacConkey agar
  • No growth on MacConkey except S. faecalis
  • PCR, Lancefield grouping and biochemical tests


Pathogenesis and Pathogenicity

  • Beta-haemolytic strains more pathogenic than alpha-haemolytic strains
  • Virulence factors include streptolysins, hyaluronidase, DNase, streptokinase and proteases
  • S. pyogenes, S. pneumoniae and some strains of S. equi have polysaccharide capsules which are antiphagocytic
  • S. pyogenes and S. equi have antiphagocytic cell wall M proteins