Micro: Rheumatic Fever Flashcards
Hx related to S.pyogenes infection (not yet RF)
Sore throat
Head Ache
Abdominal pain, N/V
Physical findings associated with S.pyogenes infection (not yet RF)
Pharyngeal erythema and exudate*
Enlarged/Tender Cervical lymph nodes
Palatal Petechiae
Running fever (102 or so)
The differential between viral and bacterial sore throats is …
presence of purulence with bacterial
Both viral and bacterial will present with redness
How is S.pyogenes infection Dx ?
Rapid Strep Test (antigen based)
If this is negative, does not mean there is no strep (80-90% sensitive. Bacterial antigen titers may not be high enough to detect early on)
If Neg: Throat culture !
Streptoccoci Characteristics
General: Gram + Catalase - Coagulase - Faculative Anaerobes Capnophilic (Like CO2)
Lab:
Beta hemolytic
Bacitracin sensitive
PYR positive(L-pyrrolidonylarylamidase enzyme)
What else is PYR+? Enterococcus (vert similar to streptococcus)
ASO titer
anti-streptolysin O
ASO destroys RBC’s. This test can be useful in determining strep throat after the infection has been cleared. Good for determining cause of rheumatic fever
Anti-Dnase B test
Good for Strep skin infections (can be used for throat as well)
what are two physical finding associated with Scarlett Fever ?
Sandpaper Rash
Strawberry tongue
What is the S.pyogenes virulence factor associated with Strawberry tongue and Sandpaper rash ?
Pyrogenic Exotoxin
What is the most dangerous disease state associated with pyrogenic exotoxin ?
Necrotizing fasciitis
Describe the chronology of Rheumatic Fever
Patient developes strep. throat
2-3 weeks later patient presents with symptoms associated with disease
Most likely will be + for ASO
What is the virulence factor associated with Rheumatic fever ?
M-Protein
How does M-protein lead to developement of RF ?
Binds fibrinogen
Binds IgG–> Strong response –> bind auto-antigens !!!**
Binds complement factor H
discourages binding of C3b to surface
Which strains of Strep are NOT associated with causing Acute RF ?
Those which are pyodermal in nature (cause purulent rash )
What happens to virulence of Strep which have been passed between many people ?
Virulence increases !
Where will you find auto-antigens that are similar to M-protein ?
Cardiac myosin–>myocarditis etc.
Sarcolemmal membrane protein
Synovium (joints)
Articular cartilage (joints)
What percentage of people with asymptomatic pharyngitis will go on to develop Acute RF (ARF) ?
33% (1/3 as the ppt states)
Age group associated with ARF ?
School children 5-15
Which HLA type predisposes African americans to ARF ? Caucasians ?
HLA DR-2
HLA-DR4
What syndromes associated with ARF are females more prone to ?
Syndeham Chorea
Mitral Valve Stenosis
What valve is most commonly affected with ARF associated endocarditis ?
Mitral (as always)
Aschoff bodies are associated with ARF that affects what heart layer?
Myocardium
Describe ARF associated pericarditis
Inflammatory lesions of epicardial connective tissue
Fibrinous or serofibrinous exudate
Usually resolves without lesions
Jones Criteria for ARF
- Evidence of GABHS + Two major indicators
2. 1 Major indicator + 2 Minor indicators
Jones Criteria: Major manifestations
Carditis Polyarthritis Chorea Erythema marginatum Subcutaneous nodules
Jones Criteria: Minor Manifestations
Arthralgia Fever Elevated acute phase reactants Erythrocyte sedimentation rate (ESR) C-reactive protein (CRP) Prolonged PR interval Supporting evidence of GABHS infection
Clinical Manifestations that peak within the first month of ARF
Polyartheritis
Carditis
Erythema marginatum
Clinical Manifestations that peak after the first month of onset with ARF
Chorea
Subcutaneous nodules
Murmurs associated with ARF
High-pitched blowing holosystolic apical murmur of mitral regurgitation
Low-pitched apical mid-diastolic flow murmur
High-pitched decrescendo diastolic murmur of aortic regurgitation
Is mitral and aortic stenosis associated with Chronic or Acute RF associated valvular disease ?
CHRONIC (Only)
Chronic scarring of Mitral valve is described as
“fish mouth”
What happens to the chordae tendinae in Chronic rheumatoid valvulitis
shortened and thickened (these connect the papillary muscles to the Tri/Bicuspid valves)
percent of patients with polyarthritis on first attack of ARF ?
75%
Increases with age
Polyartheritis is associated with which joints in the body
Knees, ankles, elbows, wrists
What is the prognosis for polyarthritis ?
May migrate to other joints but will typically resolve in 4 weeks with no residual damage
Syndeham Chorea
St. Vitus dance
15% of cases exhibit
Rapid, purposeless movements of face, upper extremities
Seen in women more than men
What is often seen when patients with Syndeham Chorea sleep ?
The chorea subsides
Describe the hypothesis on how Syndeham chorea occurs in the setting of ARF ?
antistreptococcal antibodies cross react with proteins in basal ganglia of brain triggering an inflammatory response (PANDAS is sub-type of Syndeham that may cause OCD, Tourettes etc)
Describe erythema marginatum
serpiginous
Rash appears intermittently for weeks to months
Nonpruritic, nonpainful, erythematous
Due to vasomotor response ?
Subcutaneous nodules (Aschoff bodies in heart) are formed from edmeatous fragmented collagen fibers. Where do you often see these nodules ?
extensor surfaces of wrists, elbows, knees
Allegedly can be seen in the myocardium of the heart (known as Aschoff bodies there)
Subcutaneous nodules are associated with …
Severe Carditis !
How could ARF lead to hemoptysis ?
Valves incompetent –> backflow into lungs –> bloody coughing
