Cardiac infections Flashcards
Invasion and multiplication of microorganisms on the endocardial surface, within the endocardium, within the myocardium, and/or on the prosthetic material within the cardiac structure
Infective endocarditis
Causes of bacteremia potentially leading to infective endocarditis
Oro-dental extraction/surgery
Respiratory tract intubation/scope
GI tract scope/biopsy
Urinary tract scope/surgery
IVDU
AV fistula
Potential pathogens in infective endocarditis related to indwelling catheter, AV fistula, or hemodialysis
S aureus
S epidermidis –> coagulase negative
Potential pathogens in infective endocarditis related to dental procedure
Strep viridans
HACEK
Potential pathogens in infective endocarditis related to GI procedure
Enterococcus species
Strep gallotycius/bovis
Potential pathogens in infective endocarditis related to urinary tract procedure
Enterococcus species
Potential pathogens in infective endocarditis related to IVDU
S aureus
Pseudomonas
Candida
Virulence factors of Strep viridans that contribute to infective endocarditis
Dextran
FimA –> surface adhesins
Virulence factors of S epidermidis that contribute to infective endocarditis
Glycocalyx and slime layer –> adhesion
Common pathogens in prosthetic valve endocarditis within 2 mos of surgery
Strep epidermidis
S aureus
Gram negative aerobic bacilli
Candida
Common pathogens in prosthetic valve endocarditis that develops >2 mos after surgery
S epidermidis
Strep viridans
HACEK
Constitutional symptoms of infective endocarditis
Fever, chills, rigors
Malaise
Weight loss
Night sweats
Myalgias
Cardiac symptoms of infective endocarditis
New or changing murmur
Arrhythmia (heart block)
HF (valve insufficiency)
Major modified duke’s criteria for diagnosing infective endocarditis
2 positive blood cultures
Positive echocardiogram
New valvular regurgitation
Minor modified duke’s criteria for diagnosing infective endocarditis
Predisposing heart condition of IVDU
Fever
Vascular phenomenon
Immunologic phenomenon
Microbiological evidence of positive blood culture not meeting criteria
Amount of Duke’s criteria needed for diagnosis of infective endocarditis
2 major OR 1 major and 3 minor OR 5 minor
Bacteria that can contaminate blood cultures
Staph epidermidis
When to suspect endocarditis when
blood culture is negative
Recent antibiotic therapy or consider non-bacterial endocarditis
Gram positive cocci in chains. Alpha hemolysis on blood agar with greenish discoloration. Catalase negative. Optochin resistant. Resistant to bile.
Strep viridans
Gram positive cocci in pairs and short chains, with acute angles. Usually non-hemolytic and catalase negative. Grows in 6.5% NaCl and tolerates 40% bile. Hydrolyzes esculin.
Enterococcus species –> fecalis and faecium
Gram positive cocci in clusters. Beta hemolysis of blood agar with golden colonies. Coagulase and catalase positive.
S aureus
Gram positive cocci in clusters. Beta hemolysis of blood agar with golden colonies. Coagulase negative and catalase positive.
S epidermidis
HACEK –> slow/difficult to culture
Hemphilus
Aggregatibacter
Cardiobacterium
Eikenella
Kingella
Group of bacteria that are all gram negative baccilli/coccobacilli and part of normal oro-dental flora. All are fastidious and may be missed on routine blood cultures.
HACEK bacterias
Gram negative rod that is strictly aerobic. Blue-green pigment produced on culture with a sweet/fruity odor. Oxidase positive.
Pseudomonas aeruginosa
Duration of antibiotics in infective endocarditis
4-8 wks
Conditions where prophylaxis for infective endocarditis is indicated
Valvular defects
Hx of endocarditis
Congenital heart disease
Prosthetic valve
Post cardiac surgery/transplant
Prophylaxis for infective endocarditis
Antibiotic administered 30-60 min before dental, GI, urinary, or respiratory procedures, and I&D.
Typically amoxicillin or ampicillin
Antibiotics used for infective endocarditis prophylaxis in those with penicillin allergy
Azithromycin
Clindamycin
Latent period between GAS pharyngitis and acute rheumatic fever
1-3 wks
Main hypersensitivity reaction type in acute rheumatic fever
Type II hypersensitivity
Major JONES criteria for diagnosis of acute rheumatic fever
Erythema marginatum
Carditis
Skin nodules
Migratory polyarthritis
Number of major and/or minor JONES criteria required for diagnosis of acute rheumatic fever
2 major OR 1 major and 2 minor
Minor JONES criteria for diagnosis of acute rheumatic fever
Fever
Arthralgia
Raised ESR
Raised CRP
Prolonged PR interval
Hx of rheumatic fever or rheumatic heart disease
Positive ssRNA non-enveloped viruses spread via feco-oral route that can cause viral myocarditis
Coxsackie
Enterovirus
ECHOvirus
Risk factors for development of viral myocarditis
Children - severe
20-40 yo
Long-term steroid of NSAID use
Alcohol
Nutritional deficiencies
Pathogenesis of acute phase of viral myocarditis
IFN-alpha, IFN-beta, NK cells and other inflammatory cytokines destroy infected myocytes. Non-infected myocytes survive. Spontaneous resolution.
Pathogenesis of subacute phase of viral myocarditis
CD8 cells stimulate cytokine production. B cells recruited and lymphocytic infiltration. Results in myocardiocyte inflammation
Pathogenesis of chronic phase of viral myocarditis.
Fibrotic replacement of dead myocardiocytes or viral persistance/inflammation. Results in cardiac remodeling leading to dilated cardiomyopathy and CHF.
Clinical features of viral myocarditis
CP
Fever
Rash
Fatigue
Myalgia
Respiratory and/or GI upset
ECG findings in viral myocarditis
Non-specific ST segments elevations and T wave changes
Chronic manifestations of viral myocarditis
Dilated cardiomyopathy
CHF
Morphological forms of Trypanosoma cruzi in the body
Amastigote –> in tissue
Trypomastigote –> in circulation
Chagoma
Swelling that forms at site of infection/bite in Chagas disease
Romana’s sign
Chagoma of eyelid
ECG changes in Chagas disease dilated cardiomyopathy
Arrhythmias
Complete right bundle branch block
Cardiac complications of Chagas disease
Dilated cardiomyopathy
Cardiomegaly
Apical LV aneurysm
Causal agent in Lyme disease
Borrelia burgdorferi
Signs and symptoms of stage 1, early localized, Lyme disease
Erythema migrans
Flu-like symptoms
Erythema migrans
Bulls-eye rash seen in early Lyme disease
Signs and symptoms of stage 2, early disseminated, Lyme disease
Secondary lesions
Carditis
3rd degree complete AV block
Bell’s palsy
Migratory myalgias and/or transient arthritis
Signs and symptoms of stage 3, late disseminated, Lyme disease
Chronic arthritis
Encephalopathy
Bacteriophage encoded virulence factor that inhibits eukaryotic protein synthesis by inhibiting elongation factor 2. Affects respiratory tract epithelium, myocardium, and CNS.
Diphtheria toxin
Clinical manifestation of diphtheria toxin
Arrhythmias
Circulatory collapse
Symptoms of infectious pericarditis
Fever (viral)
Sharp, pleuritic, substernal CP that radiates to shoulder/neck
Intense pain when supine relieved when upright
Clinical signs of infectious pericarditis
Pericardial friction rub
Pericardial effusion –> muffled heart sounds
ECG changes in acute pericarditis
Widespread concave ST segment elevation
Widespread PR segment depression
Reduced QRS amplitude –> pericardial effusion
Complication of infectious pericarditis
Cardiac tamponade
Pathogenesis of syphilitic heart disease
Obliterative endarteritis (vasculitis) and vasa vasorum which weakens the aortic root wall
Result of weakening of the aortic root wall in syphilitic heart disease
Aortic dilation and aneurysm
Aortic valve regurgitation