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===
 +
 
 +
*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
 +
*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
 +
 
 +
 
 +
===[[Respiratory Bacterial Infections - Pathology#Strangles|strangles]]===
 +
 
 +
*Epidemiology
 +
**[[Respiratory Bacterial Infections - Pathology#Strangles|strangles]] is a 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
 +
**Transmitted via purulent exudate discharging from upper respiratory tract or from lymph nodes
 +
**Chronic, carrier state can occur with bacteria im the guttural pouch
 +
**A mild, atypical form can occur
 +
**''S. equi'' shed for 4 weeks beyond clinical resolution
 +
 
 +
*Clinical signs
 +
**Incubation period 3 to 6 days
 +
**Fever, depression, anorexia
 +
**Purulent nasal discharge
 +
**Swollen, painful regional lymph nodes, especially submandibular
 +
**Abscessation and rupture of lymph nodes
 +
**Guttural pouch empyema
 +
**100% morbidity; 5% mortality
 +
**Death can occur from pneumonia, breathing difficulties from swollen lymph nodes or purpura haemorrhagica (an immune-mediated disease)
 +
**Bastard strangle may occasionally occur, with abscessaation in many organs of the body
 +
 
 +
*Diagnosis
 +
**Clinical signs and history
 +
**Mucoid colonies with beta-haemolysis
 +
**Sugar fermentation allows differentiation of ''S. equi'' from ''S. zooepidemicus'' and ''S. equisimilis''
 +
**PCR to detect asymptomatic carriers
 +
 
 +
*Treatment and control
 +
**Penicillin administration to in-contact animals
 +
**Isolation of affected animals
 +
**Quaranteen in-coming animals
 +
**Avoid overcrowding and mixing different age groups
 +
**Disinfection of equipment
 +
 
 +
 
 +
===''Streptococcus suis''===
 +
 
 +
 
 +
 
 +
 
 +
===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 [[Respiratory Bacterial Infections - Pathology#Strangles|strangles]] with [[Nasal Cavity Inflammatory - Pathology#Strangles|rhinitis]], [[Nasopharynx Inflammatory - Pathology|pharyngitis]], lymphadenitis, [[Muscles Inflammatory - Pathology#Abscesses|myositis]]
 +
*''S. equi'' may be involved in [[Bacterial skin infections - Pathology#Systemic bacterial infections|cutaneous lesions]]
 +
[[Respiratory Bacterial Infections - Pathology#In Horses|URT inflammation in horses]]
 +
 
 +
* [[Peritoneal Cavity Inflammatory - Pathology#In pigs|peritonitis in pigs]]
 +
 
 +
*''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]]
 +
 
 +
*May cause [[Paranasal Sinuses Inflammatory - Pathology|sinusitis]] in horses
 +
 
 +
* Can cause vascular fragility, leading to [[General Pathology - Haemostasis#Haemorrhagic Disease Due To Vascular Fragility|haemorrhagic disease]].
 +
*Secondary invadors after [[Respiratory Viral Infections - Pathology#Equine influenza|Equine influenza]]
 +
*''S. suis'' in [[Respiratory Bacterial Infections - Pathology#Streptococcal pneumonia|pneumonia]] of pigs
 +
 
 +
*In [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]]
 +
* In [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]]
 +
 
 +
*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 horses sometimes [[Muscles Degenerative - Pathology#Ischaemia|purpura haemorrhagica]] follows, especially during recovery from [[Respiratory Bacterial Infections - Pathology#Strangles|strangles]]
 +
*In [[Cavity & Gingiva - Pathology#Catarrhal Stomatitis|catarrhal stomatitis]]
 +
 
 +
*In [[Bacterial skin infections - Pathology#Deep pyoderma|deep pyoderma]] and subcutaneous abscesses

Revision as of 12:23, 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.


Infectious agents and parasitesWikiBugs Banner.png
BACTERIA



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
  • 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


strangles

  • Epidemiology
    • strangles is a 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
    • Transmitted via purulent exudate discharging from upper respiratory tract or from lymph nodes
    • Chronic, carrier state can occur with bacteria im the guttural pouch
    • A mild, atypical form can occur
    • S. equi shed for 4 weeks beyond clinical resolution
  • Clinical signs
    • Incubation period 3 to 6 days
    • Fever, depression, anorexia
    • Purulent nasal discharge
    • Swollen, painful regional lymph nodes, especially submandibular
    • Abscessation and rupture of lymph nodes
    • Guttural pouch empyema
    • 100% morbidity; 5% mortality
    • Death can occur from pneumonia, breathing difficulties from swollen lymph nodes or purpura haemorrhagica (an immune-mediated disease)
    • Bastard strangle may occasionally occur, with abscessaation in many organs of the body
  • Diagnosis
    • Clinical signs and history
    • Mucoid colonies with beta-haemolysis
    • Sugar fermentation allows differentiation of S. equi from S. zooepidemicus and S. equisimilis
    • PCR to detect asymptomatic carriers
  • Treatment and control
    • Penicillin administration to in-contact animals
    • Isolation of affected animals
    • Quaranteen in-coming animals
    • Avoid overcrowding and mixing different age groups
    • Disinfection of equipment


Streptococcus suis

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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