Rheumatic fever Flashcards
What is acute rheumatic fever?
Systemic multiorgan illness
When does acute rheumatic fever tend to occur?
2-4weeks after pharyngitis
Why does acute rheumatic fever occur?
Cross reactivity to group A beta haemolytic streptococcus (strep pyogenes)
B cells stimulated to produce anti-M protein antibodies against the infection that cross react with other tissues (heart, brain, joints and skin)
How many children worldwide are affected by rheumatic fever?
4 million
Where is the incidence of rheumatic fever highest?
Less developed tropical countries - overcrowding
Which sex experiences more rheumatic fever?
Female
What gram stain is Streptococcus pyogenes?
Gram positive cocci
Name the two cytolytic toxins that streptococcus pyogenes produces
Streptolysin O and S
What proteins do rheumatogenic strains contain in their cell walls?
M proteins
Which criteria is used to diagnose rheumatic fever?
Revised Jones diagnostic criteria
What is the clue in the history that someone may be presenting with rheumatic fever?
Recent sore throat or scarlet fever
What clinical sign may be present in severe acute rheumatic fever
Heart murmur
Which valve is most often affected in rheumatic fever?
Mitral
Describe the diagnostic requirements of rheumatic fever
Positive throat culture for group A beta haemolytic streptococcus or elevated anti-Streptolysin O (ASO) or anti-deoxyribonuclease B titre
Describe the diagnostic requirements of rheumatic fever
Positive throat culture for group A beta haemolytic streptococcus or elevated anti-Streptolysin O (ASO) or anti-deoxyribonuclease B titre
AND
2 major criteria or 1 major and 2 minor criteria present for initial ARF
List the major criteria for acute rheumatic fever
SPECS Sydenham's chorea Polyarthritis Erythema marginatum Carditis Subcutaneous nodules
List the minor criteria for initial ARF diagnosis
CRP/ESR
Arthralgia
Pyrexia/fever
ECG
What is seen on ECG of someone with ARF
Prolonged PR interval
List the differential diagnosis for acute rheumatic fever
Septic arthritis
Reactive arthropathy
Infective endocarditis
Myocarditis
What investigations are done for rheumatic fever?
Bloods - CRP, ESR, FBC (WCC) Blood cultures - exclude sepsis Rapid antigen detection test Throat culture Anti-streptococcal serology - ASO and anti-DNASE B titres ECG - prolonged PR interval CXR - if carditis suspected, heart failure may be seen due to valvular damage Echo
What is the initial management of rheumatic fever?
Antibiotics - benzathine benzylpenicillin, phenoxymethylpenicillin, amoxicillin. In confirmed penicillin allergy, use alternatives such as cephalosporins, macrolides and clindamycin
Aspirin and NSAIDs - naproxen and ibuprofen
Assess for emergency valve replacement
In severe carditis - glucocorticosteroids and diuretics
What is the secondary prophylaxis of rheumatic fever?
IM benzathine benzylpenicillin every 3-4weeks
Oral phenoxymethylpenicillin BD
Oral sulfadiazine daily or oral azithromycin in penicillin allergy
What percentage of the population get chronic rheumatic heart disease and valvular damage from rheumatic fever?
2%
How long should ARF resolve with treatment?
2 weeks but cardiac inflammation may take months to fully resolve and relapse is common
