Difference between revisions of "Streptococci"

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#REDIRECT[[:Category:Streptococcus species]]
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|linktext =BACTERIA
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<br>
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===Overview===
 +
 
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*Cause suppurative infections in many different animals
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*Cause abscess formation and septicaemia
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*Cause mastitis, metritis, polyarthritis, meningitis
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*Often commensals on mucous membranes of upper respiratory and lower urogenital tract
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*Opportunistic infections
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===Characteristics===
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*Gram positive cocci forming chains
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*Catalase negative, facultative anaerobes
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*Fastitidious - require enriched media such as blood or serum
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*Small haemolytic, translucent colonies, some mucoid
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*Catalase negative
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*Susceptible to desiccation
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===Identification===
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*Beta haemolysis (complete with clear zones surrounding colonies)
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*Alpha haemolysis (partial with green zones surrounding colonies)
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*Lancefield grouping - serology based on group-specific polysaccharide in cell wall
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*Biochemical testing
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===Pathogensis and Pathogenicity===
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*Beta-haemolytic strains more pathogenic than alpha-haemolytic strains
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*Virulence factors include streptolysins, hyaluronidase, DNase, streptokinase and proteases
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*''S. pyogenes, S. pneumoniae'' and some strains of ''S. equi'' have polysaccharide capsules which are antiphagocytic
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*''S. pyogenes'' and ''S. equi'' have antiphagocytic cell wall M proteins
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===Clinical infections===
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*Primary or secondary infections following viral infection
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*Neonatal septicaemia related to maternal genital tract infection
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*Strangles
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**Highly infectious disease of horses caused by ''Streptococcus equi'' subsp. ''equi''
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**Upper respiratory tract disease with fever and abscessation of regional lymph nodes
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**Outbreaks in groups of young horses
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**
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===Diagnosis===
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*Swabs of pus or exudate cultured on blood agar and MacConkey agar
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*No growth on MacConkey except ''S. faecalis''
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*PCR, Lancefield grouping and biochemical tests
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===Treatment===
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===Control===
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*Haemolytic streptococci of Lancefield group C are common inhabitants of the equine nasopharynx
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*''Streptococcus zooepidemicus'' and ''S. equisimilis'' are usually non-pathogenic
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*''S. equi'' is more pathogenic and is the cause of [[Respiratory Bacterial Infections - Pathology#Strangles|strangles]] with [[Nasal Cavity Inflammatory - Pathology#Strangles|rhinitis]], [[Nasopharynx Inflammatory - Pathology|pharyngitis]], lymphadenitis, [[Muscles Inflammatory - Pathology#Abscesses|myositis]]
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*''S. equi'' may be involved in [[Bacterial skin infections - Pathology#Systemic bacterial infections|cutaneous lesions]]
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[[Respiratory Bacterial Infections - Pathology#In Horses|URT inflammation in horses]]
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* [[Peritoneal Cavity Inflammatory - Pathology#In pigs|peritonitis in pigs]]
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*''S. zooepidemicus'' can cause similar signs to [[Respiratory Bacterial Infections - Pathology#Strangles|strangles in horses]], may accompany [[Bronchi and Bronchioles Inflammatory - Pathology#Chronic obstructive pulmonary disease (COPD)|COPD]]
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*May cause [[Paranasal Sinuses Inflammatory - Pathology|sinusitis]] in horses
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* Can cause vascular fragility, leading to [[General Pathology - Haemostasis#Haemorrhagic Disease Due To Vascular Fragility|haemorrhagic disease]].
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*Secondary invadors after [[Respiratory Viral Infections - Pathology#Equine influenza|Equine influenza]]
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*''S. suis'' in [[Respiratory Bacterial Infections - Pathology#Streptococcal pneumonia|pneumonia]] of pigs
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*In [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]]
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* In [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]]
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*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]]
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*In horses sometimes [[Muscles Degenerative - Pathology#Ischaemia|purpura haemorrhagica]] follows, especially during recovery from [[Respiratory Bacterial Infections - Pathology#Strangles|strangles]]
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*In [[Cavity & Gingiva - Pathology#Catarrhal Stomatitis|catarrhal stomatitis]]
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*In [[Bacterial skin infections - Pathology#Deep pyoderma|deep pyoderma]] and subcutaneous abscesses

Revision as of 12:05, 29 December 2008

 This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing.


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BACTERIA



Overview

  • Cause suppurative infections in many different animals
  • Cause abscess formation and septicaemia
  • Cause mastitis, metritis, polyarthritis, meningitis
  • 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


Pathogensis 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


Clinical infections

  • Primary or secondary infections following viral infection
  • Neonatal septicaemia related to maternal genital tract infection
  • Strangles
    • Highly infectious disease of horses caused by Streptococcus equi subsp. equi
    • Upper respiratory tract disease with fever and abscessation of regional lymph nodes
    • Outbreaks in groups of young horses


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


Treatment

Control

  • Haemolytic streptococci of Lancefield group C are common inhabitants of the equine nasopharynx
  • Streptococcus zooepidemicus and S. equisimilis are usually non-pathogenic
  • S. equi is more pathogenic and is the cause of strangles with rhinitis, pharyngitis, lymphadenitis, myositis
  • S. equi may be involved in cutaneous lesions

URT inflammation in horses

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