Streptococcus Flashcards
- Are staphs catalase + or -?
- Are streps catalase + or -?
- Staphs are catalse +
- Streps are catalase -
What change in the RBCs contributes to alpha hemolysis?
RBCs are still present in the media but the hemoglobin has been changed to methemoglobin
- What are the groups used to group the streptococci?
- How are they grouped?
- Lancefield groups
- Cell wall carbohydrates
Streptococcus capsule:
Important with some streptococcual groups, especially ____ which have a capsule composed of ____ ____. This not only masks the organism but mimics ____ ____. Protects from ____.
Streptococcus capsule:
Important with some streptococcal groups, especially group A which have a capsule composed of hyaluronic acid. This not only masks the organism but mimics host tissues. Protects from phagocytosis.
List 5 toxins of Streptococcal species:
- Streptolysin-O
- Streptolysin-S
- Streptokinase
- DNase
- Hyaluronidase
What toxin is being described?
Leukotoxin
Attacks RBCs
Causes complete hemolysis
Toxic to platelets and fibroblasts
Very antigenic
Streptolysin-O
Which toxin is being described?
Less toxic
Non-antigenic
Produces the hemolysis that is usually seen
Streptolysin-S
Which toxin is being described?
In addition to lysing fibrin, this enzyme is able to cleave C3.
Streptokinase
(fibrinolysin)
All strains of Group A streptococci produce at least one ___ that assists in ____.
All strains of Group A streptococci produce at least one nuclease that assists in liquefaction of pus and obtaining nutrients.
Hyaluronidase breaks down ____ ____ in tissues and is considered to be a ____ ____.
Hyaluronidase breaks down hyaluronic acid in tissues and is considered to be a spreading factor.
Group A streptococcus is synonymous with what?
Strep pyogenes
- What is the natural habitat of strep pyogenes?
- True or False: most children have been infected with this organism by the time they are 10.
- True or False: different M-protein types tend to circulate through susceptible populations.
- Human pharyngeal and tonsillar areas
- TRUE
- TRUE
What is the major virulence facotr of Group A streptococci?
M-proteins
What does Group A strep cause in humans?
Strep throat
Scarlet fever
Sinusitis
Heart valve lesions
Glomerulonephritis
Rheumatic fever
Erysipelas
Necrotizing fasciitis
What toxins produce the rash and fever in scarlet fever?
Erythrogenic toxins
Which organism(s) is/are in lancefield group C?
Strep equi subspecies equi
Strep equi subspecies zooepidemicus
How is strep equi transmitted from horse to horse?
Fomite
Contact
Droplet
Where is Strep equis habitat?
Horse upper respiratory tract and reproductive tract
From the respiratory tract, how does strep equi cause disease in a horse?
In the respiratory tract, the organism enters through the nasal epithelial cells and tonsils and travels via the lymph to the submandibular and other lymph nodes of the head and neck.
Which virulence factor is part of strep equi and serves an antiphagocytic purpose?
M-protein
Which is the most common cause of metritis in horses?
Strep zooepidemicus
What has been responsible for recent outbreaks of hemorrhagic pneumonia is dogs?
Strep zooepidemicus
What is the cause of “alpaca fever” in South America?
Strep zooepidemicus
What is the natural habitat of strep zooepidemicus?
Skin
Upper respiratory mucosa
Tonsillar & phyarngyeal lymphoid tissues
