Difference between revisions of "Streptococci"

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#REDIRECT[[:Category:Streptococcus species]]
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|linkpage =Bacteria
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|linktext =BACTERIA
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<br>
 +
 
 +
===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 [[Peritoneal Cavity Inflammatory - Pathology#In pigs|peritonitis in pigs]],  [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]], [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]], [[Cavity & Gingiva - Pathology#Catarrhal 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]]
 +
*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
 +
 
 +
 
 +
===[[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''
 +
**[[Respiratory Bacterial Infections - Pathology#In Horses|upper respiratory tract disease of horses]] with fever and abscessation of regional lymph nodes
 +
**Causes [[Nasal Cavity Inflammatory - Pathology#Strangles|rhinitis]], [[Nasopharynx Inflammatory - Pathology|pharyngitis]], lymphadenitis and [[Muscles Inflammatory - Pathology#Abscesses|myositis]]
 +
**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 [[Muscles Degenerative - Pathology#Ischaemia|purpura haemorrhagica]](an immune-mediated disease)
 +
**Bastard strangle may occasionally occur, with abscessaation in many organs of the body
 +
**''S. equi'' may be involved in [[Bacterial skin infections - Pathology#Systemic bacterial infections|cutaneous lesions]]
 +
 
 +
*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''===
 +
 
 +
*Meningitis, arthritis, septicaemia and [[Respiratory Bacterial Infections - Pathology#Streptococcal pneumonia|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, [[Paranasal Sinuses Inflammatory - Pathology|sinusitis]] and navel infections in horses
 +
*''S. zooepidemicus'' can cause similar signs to [[Respiratory Bacterial Infections - Pathology#Strangles|strangles in horses]] and may accompany [[Bronchi and Bronchioles Inflammatory - Pathology#Chronic obstructive pulmonary disease (COPD)|COPD]]
 +
*Secondary invador after [[Respiratory Viral Infections - Pathology#Equine influenza|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 [[Haemostasis - Pathology#Haemorrhagic Disease Due To Vascular Fragility|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 [[Bacterial skin infections - Pathology#Deep pyoderma|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

Revision as of 20:38, 13 August 2009

 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
  • 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


Strangles

  • Epidemiology
    • Strangles is a highly infectious disease of horses caused by Streptococcus equi subsp. equi
    • upper respiratory tract disease of horses with fever and abscessation of regional lymph nodes
    • Causes rhinitis, pharyngitis, lymphadenitis and myositis
    • 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
    • S. equi may be involved in cutaneous lesions
  • 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

  • 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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