Difference between revisions of "Category:Streptococcus species"

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(Created page with '{{review}} ===Overview=== *Cause suppurative infections in many different animals *Cause abscess formation and septicaemia *Cause mastitis, metritis, polyarthritis, meningitis …')
 
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[[Streptococcus equi subsp. equi]]
  
  
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===[[Respiratory Bacterial Infections - Pathology#Strangles|Strangles]]===
 
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*Epidemiology
 
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**[[Respiratory Bacterial Infections - Pathology#Strangles|Strangles]] is a highly infectious disease of horses caused by ''Streptococcus equi'' subsp. ''equi''
 
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**[[Respiratory Bacterial Infections - Pathology#In Horses|upper respiratory tract disease of horses]] with fever and abscessation of regional lymph nodes
 
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**Causes [[Nasal Cavity Inflammatory - Pathology#Strangles|rhinitis]], [[Nasopharynx Inflammatory - Pathology|pharyngitis]], lymphadenitis and [[Muscles Inflammatory - Pathology#Abscesses|myositis]]
 
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**Outbreaks in groups of young horses
 
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**Transmitted via purulent exudate discharging from upper respiratory tract or from lymph nodes
 
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**Chronic, carrier state can occur with bacteria im the guttural pouch
 
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**A mild, atypical form can occur
 
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**''S. equi'' shed for 4 weeks beyond clinical resolution
 
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*Clinical signs
 
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**Incubation period 3 to 6 days
 
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**Fever, depression, anorexia
 
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**Purulent nasal discharge
 
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**Swollen, painful regional lymph nodes, especially submandibular
 
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**Abscessation and rupture of lymph nodes
 
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**Guttural pouch empyema
 
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**100% morbidity; 5% mortality
 
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**Death can occur from pneumonia, breathing difficulties from swollen lymph nodes or [[Muscles Degenerative - Pathology#Ischaemia|purpura haemorrhagica]](an immune-mediated disease)
 
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**Bastard strangle may occasionally occur, with abscessaation in many organs of the body
 
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**''S. equi'' may be involved in [[Bacterial skin infections - Pathology#Systemic bacterial infections|cutaneous lesions]]
 
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*Diagnosis
 
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**Clinical signs and history
 
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**Mucoid colonies with beta-haemolysis
 
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**Sugar fermentation allows differentiation of ''S. equi'' from ''S. zooepidemicus'' and ''S. equisimilis''
 
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**PCR to detect asymptomatic carriers
 
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*Treatment and control
 
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**Penicillin administration to in-contact animals
 
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**Isolation of affected animals
 
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**Quarantne in-coming animals
 
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**Avoid overcrowding and mixing different age groups
 
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**Disinfection of equipment
 
  
 
===''Streptococcus suis''===
 
===''Streptococcus suis''===

Revision as of 10:21, 17 May 2010

 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.


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


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


Streptococcus equi subsp. equi


Streptococcus suis

  • Meningitis, arthritis, septicaemia and pneumonia of pigs
  • Sporadic cases of endocarditis, neonatal deaths and abortion
  • Carried in tonsils and nasal cavity of carrier pigs
  • Outbreaks occur in intensively-reared herds with poor hygiene
  • Carrier sows infect litters causing neonatal deaths
  • Meningitis with fever, tremors, incoordination, opisthotonos and convulsions
  • Treatment with penicillin; prophylactic long-acting penicillin for sows and piglets
  • Suppurative conditions in cattle, sheep, horses, cats
  • Septicaemia and meningitis in humans


Bovine streptococcal mastitis

  • S. agalactiae, S. dysgalactiae and S. uberis primarily cause mastitis
  • Also S. pyogenes, S. zooepidemicus and Enterococcus faecalis can be involved
  • S. agalactiae colonises milk ducts causing persistent infections with acute outbreaks
  • S. dysgalactiae found in the oral cavity and on the skin of the udder causes acute mastitis
  • S. uberis inhabits normal skin, tonsils and vaginal mucosa, and causes mastitis without systemic signs
  • Cause inflammation of mammary tissue and clots form in milk
  • Milk samples are cultured on blood agar, Edward's medium and MacConkey agar for diagnosis


S. equisimilis

  • Found on skin and vagina of horses
  • Causes abscesses, endometritis and mastitis in horses
  • Suppurative conditions in pigs, cattle, dogs, birds


S. zooepidemicus

  • Colonises mucous membranes
  • Causes mastitis, pneumonia, sinusitis and navel infections in horses
  • S. zooepidemicus can cause similar signs to strangles in horses and may accompany COPD
  • Secondary invador after equine influenza
  • Colonises skin and mucous membranes of cattle, lambs, pigs and poultry and causes suppurative infections and septicaemia
  • Can cause vascular fragility, leading to haemorrhagic disease


Enterococcus faecalis

  • Colonises intestinal tract
  • Causes opportunistic suppurative infections in many species


S. canis

  • Found in vagina and anal mucosa of carnivores
  • Neonatal septicaemia, suppurative infections, toxic shock syndrome
  • In deep pyoderma and subcutaneous abscesses


S. pneumoniae

  • Found in upper respiratory tract of primates
  • Causes septicaemia, pneumonia and meningitis
  • Pneumonia in guinea-pigs and rats


S. porcinus

  • Submandibular lymphadenitis in pigs
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