Flashcards in Microbiology of Heart Disease Hersh DSA Deck (53)
acute endocarditis- clinical features
-fevers, chills, weakness, lassitude
-fever- most consistent sign!!
-murmurs- 90% of pts with left-sided IE
acute endocarditis- complications
-GN (glomerular ag-ab complex deposition)
-erythematous or hemorrhagic nontender lesions on palms/soles (Janeway lesions)
-subcutaneous nodules in pulp of digits (Osler nodes)
-retinal hemorrhages in eyes (Roth spots)
4 major forms of vegetative endocarditis- morphology
-RHD- small, warty vegetations along closure lines of valve leaflets
-IE- large, irregular masses on valve cusps that extend onto chordae
-NBTE (nonbacterial thrombotic endocarditis)- small,bland vegetations attached at line of closure
-LSE (libman-sacks endocarditis)- medium vegetations on either/both sides of valve leaflets
Duke criteria- pathologic
-microorganisms by culture or histologic examination in a vegetation, embolus, or intracardiac abscess
-histologic confirmation of active endocarditis in vegetation or intracardiac abscess
Duke criteria- clinical- major
-2 blood cultures + for characteristic organism or persistently + for an unusual organism
-echocardiographic ID of valve-related or implant-related mass or abscess
-new valvular regurgitation
Duke criteria- clinical- minor
-predisposing heart lesion or IV drug use
-immunological phenomena (GN, osler nodes, roth spots)
-microbiologic evidence- culture positive for unusual organism
-echocardiographic findings- consistent with but not diagnostic of endocarditis- worsening/changing of preexistent murmur
Viridans Group Streptococci- 3 main types of infection
-dental infections (streptococci mutans)
-endocarditis (viridans streptococcus- slowly/subacute; staph aureus- fast/acute)
-abscesses (streptococcus intermedius)
Viridans Group Streptococci- virulence, treatment, diagnostics
-normal oral flora and GI tract
-extracellular dextran- helps bind to heart valves
-gram stain, culture, resistant to optochin
Group D streptococci- 2 subtypes
-Enterococci (faecalis, faecium)
-normal bowel flora
-subacute bacterial endocarditis
-2/3rd most common cause of hospital acquired infection- prosthetic valve endocarditis!!
-resistant to ampicillin, vancomycin!
staphylococcus aureus- causes? morphology? treatment?
-acute endocarditis- high fever, chills, myalgias- no history of valvular disease; grow rapidly
-most are penicillin resistant- use nafcillin, dicloxacillin
-cephalosporins- cefazolin, cephalexin
staphylococcus epidermis- morphology, treatment, infects?
-catalase-positive; coagulase neg!!
-lives in our skin- compromised hospital pts withI lines
-infections of prosthetic valves!!- most frequent organism from infected prosthetic devices!!
HACEK organisms- characteristic
-fastidious, very slow growing
myocarditis- pathogenesis- most common cause?
-viral infections- most common cause!!
-Coxsackie viruses A and B- most cases
-CMV, HIV, influenza- other cases
-infl cytokines can cause myocardial dysfxn
myocarditis- other causes
-nonviral agents- mostly Trypanosoma cruzi (Chagas disease)
-Trichinosis (Trichinella spiralis)- most common helminthic disease
-Lyme disease (Borrelia burgdorferi)
-Diphtheritic myocarditis (Corynebacterium diphtheriae)
active myocarditis- morphology
-interstitial infl infiltrate assoc with focal myocyte necrosis
-diffuse, mononuclear, predominantly lymphocyte infiltrate
infective endocarditis- essentials of diagnosis
-preexisting organic heart lesion
-positive blood cultures
-evidence of vegetation on echocardiography
-new or changing heart murmur
-evidence of systemic emboli
native valve endocarditis- caused by?
-Group D streptococci
-duration- few days/wks
-peripheral lesions- petechiae, subungual (splinter) hemorrhages, osler nodes, Janeway lesions, Roth spots
endocarditis- diagnostic studies
-modified Duke criteria
endocarditis- blood cultures
-3 sets at least 1 hr apart before starting antibiotics
-agents against staphylococci, streptococci, enterococci
-vancomycin (1 gm every 12 hrs) plus ceftriaxone (2 gm every 12 hrs)!!!!