Intro to CV Infectious Disease Flashcards
What are the 7 CV infectious diseases we learn about?
endocarditis myocarditis pericarditis rheumatic heart diseae catheter-related infections machine infections (valves, pacemakers, defibrillators,) Rocky Mountain Spotted Fever
Is infectious endocarditis a bacterial or viral disease?
bacterial
What is a physical predisposing factor to infectious endocarditis? WHy?
an underlying heart defect - congenital or prior/chronic damage to endocardium
injury to the epithelium causes aberrant blood flow and allows for infection directly by organisms (and for clots)
What do the bacteria grow to form on valves and heart tissue in infectious endocarditis?
vegetations - collections of bacteria, platelets, fibrin and inflammatory cells
What is a behavioral predisposing factor to endocarditis?
IV drug use (typically right-sided infecitons)
What are the common portals of entry for the pathogens that cause endocarditis?
oral cavity, skin and upper respiratory tract into the bloodsream
What culture will typically be positive in infectious endocarditis?
blood cultures will be positive for bacteria
What symptoms are associated with subacute onset of infectious endocarditis?
low grade fever, night sweats, chills, fatigue, malaise, weakness, anorexia and low back pain
What physical exam findings will be noted in subacute infectious endocarditis?
cardiac murmur conjuncitval petechiae splinter hemorhage in the nails Osler Nodes Roth's spots Janeway lesions
What lab findings will also be positive in endocarditis besides the blood cultures?
anemia elevated sed rate elevated CRP presence of rheumatoid factor circulating immune complexes
What are the most likely causative microorganisms for infectious endocarditis?
streptococcus spp. (viridans) - most common community acquired
Staphylococcus aureus - most common Nosocomial and in IV drug users)
Enterococci
Coagulase-negative staphylococci
Some can be culture-negative
IV drug users can also have polymicrobial infections or gram-negative bacillia
Is myocarditis typically a viral or bacterial infections?
viral
What are the common symptoms of myocarditis?
flu-like illness with chest pain
some patients will have an arrhythmia and feel like they are having a heart attack
What are the two more common microorganisms for myocarditis? Which one in chidlren?
Coxsackie B virus
Adenovirus - children
Is pericarditis typically a bacterial or viral illness?
viral
but bacterial can also occur by hematogenous spread, trauma or cardiac surgery
What time of the year is viral pericarditis more common? Coinciding with what?
spring and summer; coinciding with higher incidence of enterovirus infections
In pericarditis, when does the chest pain because exacerbated?
When they swallow or when they are supine
What will all patients have on exam in pericarditis?
tachycardia
characteristic three-component friction rub
EKG changes frequent
Lab tests after what procedue can help establish etiology in pericarditis?
pericardiocentesis
What are the 4 most common viruses to cause pericarditis?
coxsackie A and B
Echoviruses
Influenza virus
What are the 4 most common bacteria to cause pericarditis?
stpahylococcus aureus
Strep pneumoniae
Haemophilus influenza
Neisseria meningitidis
Rheumatic heart disease follows what bacterial infection?
strep pyogenes pharyngitis
In Rheumatic heart disease, the damage to the heart muscle and valves is attributed to what?
autoantibodies
What is the definitive clinical indicator for rheumatic heart disease?
mitral stenosis following pharyngitis with rash
What is the main source of the bacteria in intravascular-catheter-related infections?
the skin
What viral factor allows bacterial to colonize in catheter related infections?
biofilms
What’s the most common causative agent for catheter-related infections?
staph aureus
which valve is most often affected by endocarditis?
the mitral valve (tricuspid for IV drug users)
How do acute and subacute endocarditis differ?
acute - extremely febrile with rapid progression to death. seeds infection in distal sites and rapidly damages the heart
subacute - more indolent course, gradually progressive, rarely seeds ifnection, damages heart slowly
What are ROth spots
white-centered retinal hemorrhages seen on fundoscopic exam in endocarditis
What does strep viridans refer to?
strep that undergoes alpha hemolysis - green on blood agar
what’s the most common species of strep viridans?
strep mutans
What are the Duke Criteria for endocarditis?
2 major criteria or 1 major criteria/3 minor or 5 minor met:
major: 1. positive blood cultures (2 separate in time) 2. evidence of endocardial involvements
minor; 1. predisposition (heart condition or drugs) 2. fever above 38 C or 100.3 F
3. Vascular phenomena (arterial emboli) 4. Immunological phenomena Roth’s spots
5. Microbial evidence - postivie blood culture but not meeting major criteria
What are janeway lesions?
non-tender small haemorrhagic lesions on palms and soles
What are osler’s nodes?
painful, red, raised lesions on hands and feet (immune complex deposition)
What is the number one cause of endocarditis?
staph aureus from the skin
How does strep aureus evade the host defenses?
protein A to bind Fc of IgG
coagulase (forms fibrin coast around organism)
hemolysins and leukocidins to destroy blood cells
How does staph auerus penetrate deep tissues?
hyaluronidase to break down CT
staphylokinase to lyse formed clots
lipase to break down fat
Which one can infect HEALTHy valves: staph aureus or step viridans?
staph
What can the viridans species produce to help glycocalyx formation go assist colonization?
dextran
what’s the most common strep viridans species?
strep mutans
How can a strep pyogenes infection lead to damaged heart valves?
It has an M protein (resists phagocytosis) which our body will mount an immune response to. the antibodies then cross react with heart valve tissue
What type of hypersensitivity reaction is the strep pyogenes damage to the heart?
type 2 (antibody mediated)
What’s the general treatment for endocarditis?
high dose, long-term treatment with an orgnism-specific bactericidal antibiotic
What is myocarditis an infection of?
the myocardium, or middle layer of the heart wall
Why do Coxsackie B virus and Adenovirus cause myocarditis, but not coxsackie A?
Because it can’t bind the receptor present on the myocardial cells, the CAR receptor
When does rhematic fever/ heart disease typically occur? in what age group?
2-4 weeks after strep infection
5-15 year olds most common
What are the symptoms of rheumatic fever?
pain and swelling of alrge joints, fever, weakness, muscle aches, SOB, CP, N/V, cough, circular rash, lumps under skin
Prosthetic valve infections during the initial year following surgery are usually from what? How about later than a year after?
staphylococcus epidermidis
after - streptococcus viridans
Infections within the first two weeks post pacemaker/defibrillator implant are usually from what? How about after 2 weeks?
staphylococcus aureus
then coagulase negative staph species like Staph epidermidis
A high percentage of patients with an infected valve, pacemaker or defibillator will also have what type of infection?
endocarditis
What’s the most common rickettsial infection in the US?
rocky mountain spotted fever
How does rocky mountain spotted fever cause hemorrhages?
The rickettsia spread through the body in the blood and are engulfed by the endothelial cells, were they multiply. This multiplication causes leakge of RBCs from the vessels, causing the petechial rash and hemorrhages.
What are the symptoms or rocky mountain spotted fever?
fever, HA, abd pain, vomiting, muscle pain. Rash may develop after the first few days or never develop
What is the first line of treatment ro rocky mountain spotted fever?
Doxycycline
What tick spreads rickettsia?
the dermacentor wood tick or the dog tick
