10 - Rheumatic Fever + IE

What is the pathogen that causes rheumatic fever?

Streptococcus pyogenes, group A

How do we identify S. pyogenes in…

• Microscope

• Labs

• Gram positive cocci in chains

• Coagulase negative, catalase negative, beta hemolysis

What is rheumatic fever, simply?

An autoimmune condition that occurs 1-4 weeks after a S. pyogenes infection where the body mistakes the body’s proteins, such as the heart valves, for bacteria and attacks them via complement, macrophage, and neutrophils

Another sequelae that can be seen with rheumatic fever is

• Post-streptococcal glomerulonephritis

What part of S. pyogenes is the one that causes rheumatic fever, through what process?

M protein, since they can look alike to heart proteins and other body proteins called molecular mimicry

Acute rheumatic fever demographic and recurrent RF chance

Children 5-15, and if we’ve had it before, the chance of getting it again is 50%

Do we look for the GAS or antibodies when a patient show up w rheumatic fever symptoms, and why? How do we know if the test results are enough?

Antibodies, because the bacteria is one by then

• ASO(Antistreptolysin O titer)

• Anti-DNA B(Anti-DNase B)

If the serum titer exceeds the ULN

5 major criteria of ARF, and how many are needed?

• Carditis, arthritis, chorea, erythema marginatum, subcutaneous nodules

• 2 major criteria are needed, or 1 major with 2 minor manifestations

What is carditis, and how does it happen in rheumatic fever?

Carditis is inflammation of the heart, and it can happen to all of the endocardium, myocardium, and pericardium, specifically the left sided valves, aka part of the endocardium

• It can cause long term damage called rheumatic heart disease

What is arthritis, and how does it happen in rheumatic fever?

Arthritis is inflammation of the joints, and it happens because it shares some structural reference to M proteins as well, and can get attacked

• The joints damaged here are the major ones, and in a migratory fashion, one joint first, then another one next

What is sydenham chorea, and how does it happen in rheumatic fever?

Involuntary dance-like movements along with mood swings and slurred speech due to the cross reaction of antibodies vs neurons in the basal ganglia

• This shows up later than the other symptoms

What is erythema marginatum, and how does it happen in rheumatic fever?

A well-defined rash with a red border and non-red center due to the antibodies causing local effects at the skin

What is are subcutaneous nodules, and how does it happen in rheumatic fever?

Small bumps under the skin, painless and found over bony tendons also due to inflammatory processes

Minor criteria of rheumatic fever

• Monoarthralgia

• Fever over 38 celcius

• ESR 30 mm/hr and more and/or CRP 3 mg/dL or more

• Prolonged PR interval

Why are ESR and CRP signs of rheumatic fever?

Erythrocyte sedimentation rate is a test to see how quickly the RBCs fall to the bottom and settle, and it happens faster in inflammatory states, while CRP is a protein made during inflammatory states by the liver

What are these cells and where are they found?

These are aschoff giant cells and anitschow cells, found in aschoff bodies, aka an area of inflammation in the heart during rheumatic carditis.

• Aschoff giant cells are multinucleated macrophages

• Anitschkow cells are also caterpillar cells, actiated macrophage that has a wavy, elongated protein pattern like a caterpillar(But can also appear like an eye in transverse section)

Vegetation meaning

A small growth/mass found on a heart valve, typically made of fibrin, platelets, immune cells, bacteria

Stenosis vs regurgitation

• What are they

• Relation to rheumatic fever

• Stenosis: Narrowed valve leads to smaller opening for blood to squeeze through

  • More common in chronic rheumatic heart disease, where fibrosis has lead to the valves thickening and calcifying

• Regurgitation: Valve doesn’t close completely, so blood leaks backward

  • More common in acute rheumatic fever, where the inflammation makes it harder for valves to shut properly

What is infective endocarditis?

• An infection of the endocardium, the inner lining of the heart, including the valves, most commonly caused by bacteria in the bloodstream

Infective endocarditis is more common in ___

People with other heart diseases

Types of infective endocarditis

Acute(Days) and subacute/chronic(Weeks/months)

What are the main infective endocarditis pathogens, and which ones are the main causes of acute IE?

1. S. aureus, classic cause of acute IE

2. Strep viridans, classic source during dental procedures

3. Enterococcus, enters via the GI

4. HACEK, gram negative, often missed in culture due to slow growth

Why is IE so hard to treat, and how does it affect treatment?

The biofilm, so we have to extend treatment to 4-6 weeks

Infective Endocarditis symptoms

1. Local: Damages the heart valves and surrounding areas, causing regurgitation, fistula, etc.

2. Emboli: Can travel to other parts of the body and cause infarcts, strokes, and signs like Janeway lesions

3. Immune complex mediated signs like Roth spots and Osler nodes

What is this?

Janeway lesions at the eminences(Septic embolism), Osler nodes at the fingertips(Immune complex)

What is this?

Roth spots, note their central pallor

4 Diagnostic Pillars of IE

1. Matching clinical picture and risk factors(New murmur, IV drug us, prosthetic valve, etc.)

2. Microbiological evidence(3 or more positive cultures all one hour apart)

3. Cardiac imaging

4. Body imaging for end organ damage

A combination of these are required

Treatment of IE

1. Parenteral anti microbial drugs

2. Surgery if there is valve destruction bad enough to cause heart failure or shock, uncontrolled infection even after antibiotics, preventing embolism(if the vegetation is massive)