04-23 Bacteremia & Endocarditis Flashcards
(35 cards)
Intermittent vs. Continuous Bacteremia
—intermittent is due to infx and obstruction (e.g. pylo, cholecystitis), undrained abscesses
—Continuous is due to an endovascular source (e.g. infectious endocarditis, infected grafts/shunts, infected arterial aneurysm
Sort these pathogens into normal flora (often contaminant) vs. likely pathogen. —Coag-neg staph —Anaerobes —Propionibacterium acnes —Bacillus spp —Strep viridans —Strep pyogenes —Strep pneumoniae —Gram neg bacilli —Staph aureus
nl flora —Coag-neg staph (unless FB) pathogen—Anaerobes nl flora —Propionibacterium acnes nl flora —Bacillus spp nl flora —Strep viridans pathogen—Strep pyogenes (GROUP A) pathogen—Strep pneumoniae pathogen—Gram neg bacilli pathogen—Staph aureus
Contaminants usually:
—grown on just on one of the two or three cultures you drew.
—present without left-shift
—have no 1°infx or predisposing
infective vs. marantic endocarditis
infective is infection of valves or mural endocardium
marantic has sterile vegetations due to malig or CT dz
Acute vs. Subacute endocarditis
Acute: rapid progression, presents w/in 1 wk of sx onset
—abrupt onset (pt remembers start)
—due to INVASIVE pathogen (S. aureus, β-hemolytic strep, Pneumococcus)
—occurs on normal or abnl valves
—heart murmur ∆ing rapidly → CHF
—systemic sx: rigors & high fever
—More cutaneous and visceral emboli
Subacute: SBE sx may start weeks to months before presentation
—due to low-grade pathogens (Viridans strep, coag-neg staph)
—occurs on ABNORMAL valves
Pathogenesis
- jet lesion (turbulent flow) or trauma (catheters, particles from IVDU) or chronic inflammation →
- local thrombosis →
a. acts as nidus for infection
b. fibrin-plts blocks PMNs from bacteria
Predisposing factors to endocarditis in native valves besides IVDU, MVP, degen valve, rheumatic heart dz etc.
—poor dental hygiene
—dialysis
—prev. endocarditis
Viridans strep
—species
—sp. esp common in elderly?
Viridans streptococci are part of nl oral and colonic flora
—S. sanguis, S. bovis, S. mutans, S. mitis
—S. bovis common in elderly w/ chronic lesions, cancer
Microbe causing IE in older men?
enterococci in men with BPH or other persistent bladder outlet obstruction
—also generally common in nosocomial
Polymicrobial IE common in?
IVDU (putting needle in mouth, wiping it on something)
Top Causes of IE?
S. aureus now = Viridans Strep spp.
—Staph esp in IVDU and nosocomial
Group of non-classic organisms that can also causes IE
HACEK —Haemophilus —Actinobacillus —Cardiobacterium hominis —Eikenella —Kingella
Other non-classic IE organisms
Bartonella spp. (cat-scrath, trench fever) Q fever (Coxiella burnetii) Nutritionally-variant strep Chlamydia spp. Legionella spp. Brucella spp. Fungi
Most common non-culture finding in SBE?
—Others?
Fever (95%)
Others: anorexia, wt loss, malaise, night sweats myalgias murmur emoblic stigmata (petcchiae on skin, conjuctivae) splenomegaly
Osler’s nodes
tender subQ nodules often in pulp of digits or thenar eminence; due to immune complex
Splinter hemorrhages
linear, red at first then brown, lesions under the nails due to emboli
Janeway lesions
nontender erythematous, hemorrhagic, or pustular lesions, often on palms or soles
Embolus sites
Stroke Amaurosis fugax Acute abd pain, ileus, GI bleed MI Spleen Kidney (micro hematuria, renal insuff)
IE in IVDUs
—Usual organisms
—Which valve?
—Presentation
Organisms
—S. aureus, Gm-negs (esp Pseudomonas), polymicrobial, Candida albicans
—Tricuspid valve often
–Present w/ high fever, cough, chills, malaise, pleuritic CP (septic pulmonary emboli = hallmark of R-sided IE)
True or false: mechanical valves have a higher rate of IE than bioprosthetic valves?
False, the two types have comparable rates of IE
Incidence of IE in prosthetic valve pts?
—Time correlation w/ source of infx?
1-3% w/in 1 year s/p inplant
—if w/in 2 mos, infx likely nosocomial
—if >12 mos s/p = “community acquired”
Duke Criteria for Dx of IE
MAJOR CRITERIA
—Typical orgs or 2 sep BCs or persistently (+) BCs
—Endocardial involve (regurg, echo proof)
MINOR CRITERIA —Predispos (IVDU, prev IE, valvulopathy) —Fever >38°C —Vascular phenomena —Immun phenom (RF, GN, Osler's nodes, Roth spots) —Micro findings that don't meet MAJ CRIT
[Definitive if 2 MAR or 1 MAJ + 1 MINOR or 3 MINOR]
Roth spots
retinal hemorrhages with white or pale centers composed of coagulated fibrin
What IE Complications do you need to worry about?
—CHF —heart block (if in septum) —purulent pericarditis —myocard abscess —stroke or brain abscess —mycotic aneurysm rupture (Dx w/ CT or MRI) —splenic, renal and/or hepatic emboli/abscesses —iliac/mesenteric ischemia
mycotic aneurysm
“an aneurysm arising from bacterial infection of the arterial wall. It can be a common complication of the hematogenous spread of bacterial infection” [wiki]
—classic mushroom shape (thus “mycotic”)
