Micro-Pai quiz for Infective endocarditis, Myocarditis and Pericarditis

Common bugs causing subacute endocarditis of native valve

Streptococcus viridans group: S. mutans/ S.mitis/ S.anginosus/ S. salivarius/ S. mitis

Important pathogen causing acute endocarditis in prosthetic valve

Staphylococcus aureus, S. epidermidis

Most common pathogens associated with endocarditis in IV drug abusers

S.aurues, S.epidermidis, Candida albicans, Pseudomonas

For endocarditis, common valve involved in drug abusers

Tricuspid valve

Most common valve involved in endocarditis (except in IV drug abusers)

Mitral valve

Predisposing factor for S.aureus endocarditis

IV Drug abuse; valve replacement surgery

Predisposing factor for S.viridans and HACEK group infection

Dental manipulations- Tooth extraction/ root canal treatment/ oral surgeries

HACEK organisms

Haemophilus

Aggregatibacter

Cardiobacterium

Eikenella

Kingella

HACEK organisms

Slow growing gram negative organisms causing infective endocarditis

Eikenella corrodens

gram negative rod, bleach like odor, corrodes/ pits agar medium, part of human oral flora- imp cause of human bite infections

Pseudomonas aeruginosa

GNB, green pigment, fruity odor, oxidase positive

Staphylococcus aureus

GPC clusters, Catalase positive, Coagulase positive

Staphylococcus epidermidis

Infects prosthetic devices and catheters. Component of normal skin flora. Contaminates blood cultures.

Staphylococcus epidermidis

GPC clusters, catalase positive, Coagulase negative

Candida albicans

Yeast like fungus, budding yeast cells, pseudohyphae, Germ tube test-positive

Enterococcus faecalis/ faecium

UTI, endocarditis

predisposing factor for enterococcus

Cystoscopy/ colonoscopy/ bladder manipulations

Features of enterococcus

GPC in short chains or pairs, Catalase negative, gamma hemolytic mostly, can tolerate higher salt concentrations, Bile esculin hydrolyisis positive

Commonly associated with IE in patients with carcinoma of colon

Streptococcus bovis( now called Strep gallolyticus)

Trypanosoma cruzi

causes Chagas disease

Trypanosoma cruzi infective form for man

trypomastigote forms

Reservoir and Vector for Trypanosoma cruzii

Reservoir-Armadillos; Vector-Reduviid bug also called Kissing bug/ Assasin bug

Trypanoma cruzii-diagnostic forms

Amastigotes inside tissue cells and macrophages and trypomastigotes in blood

Underlying basis for Rheumatic Heart Diseases (RHD)

Molecular mimicry. Resemblance between S. pyogenes M proteins and cardiac/ joint tissues. Type II hypersensitivity.

Diagnosis of RHD-Test for past strep infection as active Strep not found in throat

Anti-Streptolysin O titer (serological test)