Exam 1 Lecture 10 Flashcards
What group does Streptococcus pyogenes fall under?
Group A
Name some important characteristics of S. pyogenes (think structure, hemolysis, enzyme presence)
- Gram positive cocci that comes in pairs and chains
- beta hemolytic
- catalase negative
Where can S. pyogenes be found as part of the normal microbiota?
skin and nasopharynx
How does S. pyogenes spread? (2 things)
- respiratory droplets
2. direct contact
________ ____ and ______ _ bind epithelial fibronectin, which enhances bacterial adherence and entry into human cells
lipoteichoic acid
protein F
What protein is a scaffold for lipoteichoic acid and is important in binding keratinocytes?
M protein
What does the M protein bind to?
fibrinogen
The M protein is a key virulence determinant. What makes it increase virulence of S. pyogenes? (4 things)
- limits complement deposition via the alternative pathway
- it is anti-phagocytic
- sequesters and neutralizes antimicrobial peptides
- M-like proteins
What kind of capsule does S. pyogenes have?
Hyaluronic acid capsule
What is hyaluronic acid a major component of?
connective tissue (thus it disguises itself by blending in)
What is the role of C5a peptidase is S. pyogenes?
It inactivates c5, which normally functions to recruit host phagocytes
List the types of Streptococcal pyrogenic exotoxins
SPE A, B, C
Out of the 3 SPEs, which one(s) are superantigens?
A & C
_____ _ is surface bound, a cysteine protease, and an adhesin that binds host laminin. it also leads to the production of IL-1, TNFa, IL-6, which all lead to _____.
SPE B
fever
What is the function of streptokinase?
activates host plasminogen –> plasmin –> fibrin degradation (thus it degrades blood clots and further blocks the blood clotting response so that it can move more freely thru the host’s circulation)
What age group is pharyngitis common in?
school age children 5-15 yrs
What treatment is used to avoid complications of pharyngitis?
penicillin
What is the immunological complication of pharyngitis?
acute rheumatic fever
Fibrillar coiled-coil M protein share homology with _____.
myosin
The host makes antibodies to the M protein of Group A strep, but the antibodies can cross react w/ ______. These antibodies are known as ____ _____.
myocardium (muscle of the heart)
x-reactive antibodies
True or False: When acute rheumatic fever occurs, the individual may get life-long susceptibility to bacterial endocarditis.
True
What is scarlet fever?
pharyngitis (strep) w/ a characteristic rash
What leads to scarlet fever?
SPE intoxication
What are symptoms associated w/ scarlet fever? (4 things)
punctate hemorrhages on soft & hard palate, strawberry tongue, red cheeks, circumoral pallor
What is impetigo?
A form of transient skin colonization
How is impetigo spread?
Direct contact w/ an infected individual, whether it be by indirectly touching the same items or directly contacting their lesions
True or False: Impetigo is more common in young children, specifically of children aged 2-5yrs and in their face and lower extremities
True
Impetigo is more often caused by __ ______, but increased by S. pyogenes
S. aureus
What layer of skin does impetigo colonize?
superficial layers of skin (top skin layer)
How are erysipelas and cellulitis different from impetigo?
They penetrate deeper into the dermis
With erysipelas and cellulitis, the lesion is clearly demarcated and rapidly spreads. Where does infection frequently occur?
Face, often follows pharyngitis
What are symptoms associated w/ erysipelas and cellulitis?
fever and enlargement of the lymph nodes
When does acute glomerulonephritis occur?
1-4 weeks after pharyngitis and 3-6 weeks after skin infection
The M protein of some nephritic strains share ______ similarity with _______ proteins
antigen
glomerulus
Traditionally, only nephritogenic strains of group A strep pyogenes lead to ____ _________
acute glomerulonephritis
What is the most severe complication from infection w/ Group A strep pyogenes?
Streptococcal Toxic Shock Syndrome (STSS)
List the symptoms of STSS (3)
- muscular pain
- chills
- pain at focus of initial infection site
When there is enhanced invasiveness into skin and soft tissue, the bacteria begin to distribute along lines of _____.
fascia
What is necrotizing fasciitis?
Bacterial infection along our fascia that leads to death of the body’s own tissue
______ is part of our muscle and is part of what allows our muscle to move and flex without resistance or friction.
Fascia
What are the symptoms of STSS? (5)
- nausea
- renal impairment
- diarrhea
- hypotension
- shock –> organ damage
