Difference between revisions of "Streptococci"

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#REDIRECT[[:Category:Streptococcus species]]
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|backcolour =
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|linkpage =Bacteria
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|linktext =BACTERIA
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|pagetype=Bugs
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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
 +
*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 [[Muscles Degenerative - Pathology#Ischaemia|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''===
 +
 
 +
*Meningitis, arthritis, septicaemia and [[Respiratory Bacterial Infections - Pathology#Streptococcal pneumonia|pneumonia]] of pigs
 +
*Sporadic cases of endocarditis, neonatal deaths and abortion
 +
*Carried in tonsils 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
 +
 
 +
 
 +
===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
 +
 
 +
 
 +
 
 +
===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
 +
 
 +
 
 +
 
 +
 
 +
 
 +
 
 +
*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]]
 +
 
 +
 
 +
*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 [[Cavity & Gingiva - Pathology#Catarrhal Stomatitis|catarrhal stomatitis]]
 +
 
 +
*In [[Bacterial skin infections - Pathology#Deep pyoderma|deep pyoderma]] and subcutaneous abscesses

Revision as of 13:19, 29 December 2008

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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

  • Meningitis, arthritis, septicaemia and pneumonia of pigs
  • Sporadic cases of endocarditis, neonatal deaths and abortion
  • Carried in tonsils 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


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


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




  • 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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