Infectious Endo/Myo/Pericarditis

Question 1

Borrelia

Answer 1

• Gram (-) spirochete
• Microaerophile w/ aerobic metabolism
• Lyme carditis manifests as AV block (first, second, or third) - direct spirochetal infiltration/edema fibrosis of conduction system/molecular mimicry

Responsible for Lyme disease

Question 2

Leading cause of cardiac issue in Middle/South America

Answer 2

Chaga’s disease (T. cruzi)

Tryptomastigotes invade cardiac muscle and turn into amastigotes

Question 3

Cocksackie B virus

Answer 3

• Naked, icosahedral capsid
• (+) ssRNA genome
• Acid/Bile stable (fecal-oral pathogen)
• Inactivated by chlorine

Question 4

What immunoglobulin blocks initial infection/transmission of Cocksackie B virus?

Answer 4

IgA

Question 5

Physical signs/symptoms of Coxsackie B infection

Answer 5

• Pleurodynia
• Acute myopericarditis (may progress to dilated cardiomyopathy and CHF - fatal in neonates)

Pathoglogy causes ion channel pathology in heart leading to ventricular arrythmia

Question 6

Leading cause of infective endocarditis

Answer 6

S. aureus

Most common among drug users

Viridans streptococcus = second
Enterococci = third

Question 7

HACEK group causing endocarditis

Answer 7

• Haemophilus,
• Actinobacillus
• Cardiobacterium
• Eikenella
• Kingella

Question 8

What patient population does pseudomonas endocarditis present in?

Answer 8

IV drug users

Question 9

Coagulase is specific to what Staphylococcus species?

Answer 9

S. auereus

Question 10

A-disk tests sensitivity for what?

Answer 10

Bacitracin

Group A strep is

Question 11

P-disk tests sensitivty for what?

Answer 11

Optochin

Streptococcus pneumoniae is sensitive for optochin

Question 12

Endocarditis risk factors

Answer 12

Question 13

Protein A

Answer 13

Protein on S. aureus that binds Fc regions of immunoglobulins - immune evasion

Question 14

SCCmec genotypes of HA-MRSA

Answer 14

Types I-III

Question 15

SCCmec genotypes of CA-MRSA

Answer 15

Types IV-V

Question 16

Group A hemolysis

Answer 16

beta-hemolytic

Question 17

What streptococcus bacteria are alpha hemolytic

Answer 17

S. pneuomiae

Also some of the Viridans groups (S. mutans/mitins/gallolyticus)

Viridans groups result in sub-acute endocarditis

Question 18

In which phase of Trypanosoma cruzi infections is cardiomyopathy most likely to occur?

Answer 18

During chronic infection

Question 19

A 12-yr-old boy presents with dyspnea, chest pain, fever, malaise, and a skin rash. Upon chest X-ray, an enlarged cardiac silhouette is noted and an EKG shows abnormalities. A coxsackie B viral infection is suspected. In which way is the disease most likely to be transmitted?

Answer 19

Fecal/Oral transmission

Question 20

Staphylococcus aureus has the ability to convert fibrinogen to fibrin on its surface. This virulence factor prevents immune cells from getting close to it. The enzyme responsible for this activity is called?

Answer 20

Coagulase

Question 21

Enterococci bacteria are well known to be resistant to vancomycin by acquiring the van A or B resistance gene. This gene encodes for an enzyme that performs what molecular function?

Answer 21

Alters the terminal alanine residue (to lactate with Van A gene) on the NAM/NAG peptide subunit

Question 22

Which virulence factor of Staphylococcus aureus is present on the cell surface and binds to the Fc region of antibodies to prevent immune cells from gaining access to the Fc region?

Answer 22

Protein A

Question 23

Of the following symptoms of Lyme disease, which is characterized as the most defining and well-known and the most common?

Answer 23

Erythema migrans (bullseye rash)

Question 24

What family does Coxsackie B belong to?

Answer 24

The Picornavirus family

Question 25

Answer 25

D. Borrelia burgodorferi

Borrelia is tropic for the connective tissue of the heart - preferentially infiltrating the tissue of the SA/AV node

Question 26

Answer 26

C. Antibodies to Borrelia antigens

CDC now reccomends ELISA followed by ELISA w/ different Borrelia antigen for confirmatory testing

Question 27

Answer 27

C. Tuberculous pericarditis

Calcifications unique to TB pericarditis out of listed disease processes

Question 28

Answer 28

D. Red/pink bacilli

Question 29

TB cell wall composition

Illustration

Answer 29

Acid-fast staining strips away mycolic acid

Question 30

Answer 30

A. About 10%

Question 31

Answer 31

C. IFN-gamma release assay

Vaccination against TB results in positive PPD skin test

Question 32

Answer 32

C. Trypanosoma cruzi

Question 33

Answer 33

D. Romana’s sign

Question 34

Answer 34

D. Megasyndromes

Results from the infection of smooth muscle by Trypanosoma cruzi - usually esophagus and colon (tissue loses its elasticity)

Question 35

Answer 35

B. Coxsackie B virus

Pleurodynia is characteristic of Coxasckie B

Question 36

Answer 36

All are characteristic of Coxsackie B virus

Question 37

Answer 37

C. Inhibition of bacterial cell synthesis

Question 38

Answer 38

A. The Hacek group

Primary clinical presentation is endocarditis for HACEK group but rarely cause disease

Question 39

Answer 39

C. Mouth

Part of the Veridans family of streptococcus - cause dental carries

Following dental procedure - most will get a transient bacteremia - scar tissue on the heart acts as a good substrate for bacteria to form vegetations

Question 40

Answer 40

C. Alpha-hemolytic gram (+) cocci

Question 41

Answer 41

Roth spot

Microtrhombi formation and immune complex deposition seen in infective endocarditis

Question 42

How to differentiate Strep from Staph

Answer 42

Catalase test - all Staph produce catalase

Strep lack catalase

Question 43

How to differentiate S. aureus from other types of Staph

Answer 43

Coagulase test - only S. aureus is coagulase positive