10 - Group A Streptococcal Infections Flashcards
Regarding case 10, what was the initial clinical finding that 3 of 4 kids and their mother developed? What is the pathogen that usually causes this symptom?
Sore Throat
Group A strep
Regarding case 10, what was the skin finding that 2 children developed? What were the 3 potential causes for this finding?
Sun burn like rash
Strep scarlet fever
Strep TSS
Staph TSS
Regarding case 10, when assumed that the pharyngitis was caused by strep, the drug chosen to treat was _. Why?
Penicillin G
Majority of Group A strep strains are penicillin sensitive
Regarding case 10, the infecting organism was _ hemolytic. What were 2 other characteristics of the cultured colonies?
Beta hemolytic
Highly mucoid and bacitracin sensitive
Regarding case 10, what strain was found to cause the family’s illness? What is its virulence factor?
M18 Group A strep
Superantigen SPE-C
What type of inflammatory disease is associated with M18 Group A strep? This organism produces superantigen SPE-C. What is another name for the super antigen?
Rheumatic fever
Scarlet fever toxin type C
What is the criteria for rheumatic fever?
Repeated group A
streptococcal infection with the last one approximately 10 days ago, carditis, arthritis, and shaking palsy known as Sydenham’s chorea
What is the neurological disease associated with group A strep?
PANDAS
What are the 2 drugs that are used to treat M18 group A strep?
Augmentin
Clindamycin
Why must all group A strep be treated with antibiotics?
Prevents progression to rheumatic fever
What are the 4 medically significant beta hemolytic streptococci? Which causes 90% of all infections?
- Group A (β-hemolytic) S. pyogenes (90%)
- Group B (β-hemolytic) S. agalactiae
- Group C (β-hemolytic) S. equisimilis
- Group G (β-hemolytic) S. dysgalactiae
What are the 2 members of group D strep? What type of hemolysis do they display?
Enterococcus, S. bovis
α-hemolytic
What is the major criteria by which streptococci are categorized?
Acid extractable C carbohydrates allow placements in various groups
What usually alpha hemolytic streptococcus is usually part of the normal flora of the throat?
Viridans
Group A strep are typed based on their M proteins. How many of these M proteins exist? How do they assist virulence?
Over 150 M proteins
Form antiphagocytic surface proteins (MSCRAMM)
In the presence of oxygen, what mediates beta hemolysis for group A strep? What about in the absence of oxygen?
In O2 - Streptolysin S
W/out O2 - Streptolysin O and S
What is the most common infection caused by group A strep? What are 2 ways it is transmitted?
Pharyngitis
Droplet and Direct contact
What is the major skin infection transmitted by Group A strep? How is it transmitted?
Impetigo
Direct Contact
Undet what conditions is group A strep able to cause invasive disease?
It needs to get through breaks in skin
What are the 5 cell surface virulence factors associated with Group A strep?
M protein C5a peptidase Hyaluronic acid capsule Fibronectin binding proteins IgA and IgA Fc binding proteins
What cell surface virulence factors of group A strep is associated rheumatic fever? How?
M protein
Antibodies to M protein cross react with hear myosin and tropomyosin
What is the cell surface virulence factor of group A strep that repels PMNs and macrophages?
Hyaluronic acid capsule
What are the 4 secreted exotoxins associated with group A strep?
Hemolysin-Cytolysin
Streptokinase
Streptococcal pyrogenic exotoxin
Cysteine protease
What virulence factors of Group A strep are associated with necrotizing tissue damage?
Streptolyin S
Streptokinase
Cysteine Protease
What Group A strep virulence factor is diagnostic by antibody testing?
Streptolysin O
What are the serotypes of streptococcal superantigen? How do they cause illness?
SPE A, C, G-L, SMEZ, and SSA
Cause massive cytokine production and TSS
Inflammatory throat infection with fever, involving the tonsils. This is a description of _. This is associated with high or low M types of group A strep?
Pharyngitis
Low M types
Inflammatory skin infection, usually with fawn-colored
patches around mouth and nose. This is a description of _. This is associated with high or low M types of group A strep?
Impetigo
High M types
Subcutaneous, highly inflammatory infection; usually
highly marginated and having high fever. This is a description of _.
Erysipelas
When group A strep causes invasive infections, what are the 2 descriptions of likely disease provided in the notes?
– Sepsis without hypotension ± necrotizing fasciitis and
myositis
– TSS with hypotension ± necrotizing fasciitis and myositis
What is the cause of rash associated with scarlet fever? What region of the US is more associated with scarlet fever like rash?
- Delayed hypersensitivity to strep antigens and the superantigens
- More common in Northern US
Strawberry tongue is a finding associated with _
Scarlet fever
Under what conditions can superantigen cause a blunted immune response?
When it is produced in overwhelming quantities
What are the 5 diseases discussed as part of the delayed sequelae associated with Group A strep?
Rheumatic fever Acute Glomerulonephritis Guttate Psoriasis Erythema nosodum PANDAS
Development of rose-petal shaped lesions in genetically
susceptible persons following group A strep infection describes _
Guttate psoriasis
A disease of valves and veins, with painful nodular lesions, usually on arms and legs due to immune complex disease following group A strep infection describes _
Erythema nodosum
Neuropsychiatric disorder that develops followng group A strep infection refers to _
PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococci)
Carditis, fever, arthritis, Sydenhams chorea are all associated with _. This is cause by high or low type group A strep? How is it diagnosed?
- Rheumatic fever
- Low type, especially M18
- ASO (antistreptolysin O) antibody titer
How long before the manifestation of group A strep delayed sequelae diseases?
Occur 10-15 days following last infection
A immune system kidney disease associated with hypertenstion, proteinuria or hematuria that develops after group A strep Infection is likely _. Is this disease associated with high or low levels of complement in the blood? What 2 antibodoes are diagnostic?
Acute glomerulonephritis
Low circulating complement levels
Antibodies against DNase B or ASO
What type of disease is associated with a aschof bodies? Where are they found?
Rheumatic fever
Found in heart tissue
Beyond penicillin, what is another drug that can be used to treat acute pharyngitis, impetigo and erysipelas?
Azithromycin
What are the 5 steps needed for the treatment of sever invasive diseases caused by group A strep?
- Multiple antibiotics (clindamycin to shut off exotoxins)
- Supportive care for hypotension
- Tissue debridement for necrotizing diseases
- IVIG for TSS
- Activated protein C for purpura fulminans.
For children who develop rheumatic fever, how long are they treated with antibiotics? What other type of drug can be used for their treatment?
Antibiotics till 21
Also use anti-inflammatories
