STREPTOCOCCUS Flashcards
Streptococcus species are gram-positive. True or False?
True
Streptococcus species are motile. True or False?
False
Streptococcus species are non-sporeforming. True or False?
True
Streptococcus species contain catalase enzymes. True or False?
False
Streptococcus can live in aerobic and anaerobic environment. True or False?
True, they are facultative anaerobe
What are the habitats of Streptococcus?
- Saprophytes in milk
- Parasites in mucous membranes and intestines
What are the 2 classification systems used to identify Streptococcus species?
- Sherman
- Lancefield
What are the classifications of Streptococcus under Sherman system? Give their corresponding associations.
- Pyogenic - pathogenic species
- Viridans - alpha/green hemolysis
- Lactic - associated with milk
- Enterococcus - intestine
How many groups are present in Lancefield classification system?
6 + 14 = 20 groups
What are the basis of Lancefield classification system of Streptococcus?
- Serologically active carbohydrate (C substance)
- Teichoic acid (?)
Streptococcus are more fastidious bacteria therefore need enrichment with blood and serum. True or False?
True
When Streptococcus grows in milk, what does it produce?
Lactic acid
What is the virulence factor of Streptococcus that interferes with phagocytosis?
Hyaluronic acid capsule
What is the virulence factor of Streptococcus that inhibits phagocytosis and induce immunotoxic effect on polymorphs and platelets?
Protein M
What is the virulence factor of Streptococcus that is hair-like fimbriae and is responsible for attachment of streptococci to epithelial cells?
Lipoteichoic acid
Virulence factors - Extracellular products - Hemolysins: What are the hemolysins responsible for beta hemolysis?
Streptolysins O and Streptolysins S
It is a good indicator of present or past Streptococcal infections.
Antibodies to Streptolysin O
Virulence factors - Extracellular products - Hemolysins: Both Streptolysin O and Streptolysin S are sensitive to oxygen. True or False?
False, only S.O.
Virulence factors - Extracellular products - Hemolysins: Both Streptolysin O and Streptolysin S are toxic for neutrophils and macrophages. True or False?
True
Virulence factors - Extracellular products - Hemolysins: Between Streptolysin O and S, which is a protein and elicits neutralizing antibodies?
Streptolysin O
Virulence factors - Extracellular products - Hemolysins: Between Streptolysin O and S, which is a peptide therefore non-antigenic?
Streptolysin S
An extracellular product of Streptococcus that activates plasminogen to plasmin leading to digestion of fibrin clots; fibrinolysin.
Streptokinase
Extracellular enzymes that assist in production of substrates for growth and reduces viscosity of fluid containing DNA (pus)
Dnases A, B, C, D/Streptodornase
Extracellular enzyme that promotes spread of infection in tissues
Hyaluronidase
Extracellular products/toxins of Streptococcus that are low molecular weight proteins.
Erythrogenic toxin (A, B, C)
Among the types of Erythrogenic toxin, which is responsible for rashes in scarlet fever?
Group A
Extracellular enzyme that kill phagocytes produced by some Group A streptococci
NADases
Extracellular enzyme that has broad substrate specificity and is produced by Group A streptococci
Proteinase
Specie of Streptococcus that is found in secretions from infected udder; long chains
Streptococcus agalactiae
What is the appearance of S. agalactiae when inoculated on solid medium containing starch?
Brick red growth
What is the typical test used to detect the presence of S. agalactiae?
CAMP test (Christine, Atkins, Munch-Petersen)
What is the principle behind the CAMP test?
Synergistic hemolysis produced by sequential action of staphylocococcal sphingomyelinase (beta toxin) and ceramide-binding (N-acyl sphingosine) of Streptococcus agalactiae
Give the pathogenesis of S. agalactiae. (target organs, spread, symptoms/clinical signs)
- In mammary glands of cows, sheep and goats
- Spread: milker’s hands, contaminated milking machines. mouth of calves
- Enters thru teats and colonize mammary glands resulting to inflammation and fibrosis of adjoining area; milk becomes alkaline and WBC count exceed 500,000/ml; milk reduced, thin and watery
What is the method of prevention for S. agalactiae?
None (?), vaccination is not proven effective.
How do you diagnose S. agalactiae?
- Direct smears
- Colony characteristics and biochemical tests
Specie of Streptococcus that induces acute, severe mastitis
S. dysagalactiae
What classification is S. dysagalactiae in Lancefield system?
Lancefield group C
When inoculated, what discoloration does S. dysagalactiae produces?
Distinct green discoloration
Infection of S. dysagalactiae is more frequent than S. agalactiae. True or False?
False
S. dysagalactiae produces hyaluronidase. True or False?
True
Specie of Streptococcus that is a normal commensal of the skin and upper respiratory tract, tonsils, and lymphoid tissues of the horse.
S. zooepidemicus
To what specie is S. zooepidemicus closely related?
S. equi and S. equisimilis
Specie of Streptococcus that is most common cause of wound infection in horse
S. zooepidemicus
What diseases does S. zooepidemicus induces?
- Mastitis (cows)
- Fibrinous pleuritis (lambs)
- Pericarditis (lambs)
- Pneumonia (lambs)
Among the specie of Streptococcus, which is the secondary invader of viral infections of URT of foals and young horses?
S. zooepidemicus
This specie of Streptococcus induce bovine mastitis (acute but mild) and does not react in Lancefield’s grouping system
S. uberis
Which specie of Streptococcus is the most common cause of suppurative arthritis in pigs causing lameness, swelling of points, and necrosis of joint surfaces?
S. equisimilis
S. equisimilus can reside in tonsillar tissues and draining lymph nodes. True or False?
True
How do you prevent S. equisimilis infection?
Vaccination
Specie of Streptococcus that causes strangles in horses
S. equi
What is strangles?
A severe purulent infection of the upper respiratory tract
and draining lymph nodes in horses
Under electron microscope, how do you describe S. equi?
Outer surface has peach fuzz-like coating of protein
Give the 2 antigens emitted by S. equi.
R and M antigens (M protein is antiphagocytic)
In culture media, S. equi produces what hemolysis?
B-hemolysis (Oxygen-sensitive streptolysin O-like hemolysin produces wide zone of Bhemolysis)
Describe the colonies of S. equi.
Colonies matt or mucoid
- Matt colonies with irregular surface folding and look dried due to phagecontrolled hyaluronidase action on hyaluronic acid capsule
What are the routes of S. equi?
- Nasal (inhalation of infective droplets)
- Oral (ingestion)
What is the incubation period of S. equi?
3 to 6 days to 3 weeks or longer
Trace the pathway of S. equi in the body.
Enter epithelial cells of oropharynx -> become interiorized -> lymphatic
drainage to submandibular and retropharyngeal lymph nodes -> abscess
formation
Give the replication principle of S. equi.
Complement-derived chemotactic factors (C3a and C5a) released and
attract PMN cells -> poweful toxins produced by microorganisms destroy
phagocytes -> extracellular multiplication of microorganisms
What virulence factors of S. equi makes it acquire high rate of survival?
M protein and hyaluronic acid
Give the complications (disease) of S. equi infection.
- Laryngeal hemiplegia
- Gittural pouch empyema
- Purpura hemorrhagica (vaccination)
Give the symptoms of S. equi infection.
- High fever
- Small abscesses in submandibular and retropharyngeal lymph nodes; serous nasal discharge
- Rupturing of abscesses (1-2 weeks after infection)
- Bastard strangles
How do you diagnose S. equi?
- RIA, ELISA
- Mouse protection test
- Gel diffusion precipitin test
How do you prevent S. equi infection?
- Heat-inactivated bacterin or M protein-rich extracts not useful
- Avirulent, genetically modified strain stimulates local nasopharyngeal
antibodies
Give the species of streptococcus:
- Cervical lymphadenitis
- Group E
- Swine strangles
- Abscessation of mandibular, retropharyngeal and parotid lymph nodes
-> jowl abscessation
S. porcinus
Give the species of streptococcus:
- Meningitis and septicemia in young pigs
- Group D
- Zoonotic
S. suis
Give the species of streptococcus:
- Mucous membranes of dogs and cats
- Group G
- Metritis and vaginitis in bitches
S. canis
Give the species of streptococcus:
- Abundant in feces of horses
- Not known to be pathogenic
S. equinus
Give the species of streptococcus:
- No pathogenic properties but omnipresent in milk
- Common milk-souring in short chains
S. lactis
Give the species of streptococcus:
- Always present in mouth and intestinal tract of cattle
S. bovis