EXAM 1 Intravascular Infections Flashcards
what is bacteremia?
the presence of bacteria in the blood stream
describe how bacteremia can be transient
- clearance exceeds entry
- source is local infection somewhere
- skin, lungs, bone, joint, abdomen
describe how bacteremia can be continuous
- seeding exceeds clearance capacity
- endovascular infections
- septicemia (sepsis syndrome)
- resists clearance mechanisms (virulence)
what are some examples of endovascular infections?
- infective endocarditis
- infected thrombus (blood clots)
- septic thrombophlebitis
- mycotic aneurysm
- arterial wall infection
- infections of intravascular devices
describe some examples of inftavascular devices that can cause endovascular infections
- catheters
- pacemaker and defibrillator wires
- left ventricular assist devices (LVADs)
- arterial conduits
describe blood cultures
- blood removed aseptically
- dilution of blood sample into broth
- the special case of IE - timing
describe the sensitivity and specificity of blood cultures
- sensitivity
- important variable is volume
- the larger the sample, the more sensitive
- specificity
- false positivity rate varies
what are risk factors for the predisposition of endocarditis?
- congenital heart disease
- rheumatic heart disease
- conditions leading to bacteremia
- dental, urological, gastrointestinal
- intravenous drug abuse
- hospitalization
T or F
survival rates for endocarditis during pre-antibiotic era was 0%, with all dead within one year
true
describe the pathogenesis of endocarditis
- turbulent blood flow
- brings about endothelial cell activation
- body reacts by clotting
- fibrin and platelet distribution
- silent or clinical bacteremia seed sterile vegetations
- bacteria grow within fibrin vegetations
what are the host defenses for endocarditis?
- endocardium including valves, chordae, papillary muscle attachments, and atria receive their nourishment from the blood stream
- therefore, endocardium lacks capillary circulation required for neutrophil access to the site of infection
- thus, the innate and acquired immune mechanisms are subverted
given that the endocardium lacks capillary circulation, what happens to bacteria embedded within vegetations?
the bacteria is impossible to entire eradicate
infective endocarditis is characterized by ___ within vegetaitons leading to ___
- unrestricted microbial replication
- in vivo bacterial colonies
describe the two major criteria for infective endocarditis diagnosis
- continuous bacteremia
- target lesion on valve, supports, or endocardium (by ECHO or new murmur)
describe the 5 minor criteria for the diagnosis of infective endocarditis
- fever
- predisposing heart condition
- injection drug use
- embolic phenomena
- immunological phenomena
describe the microbiology of infective endocarditis
-
staphylococci
- s. aureus
- coagulase-negative staphylococci sp.
-
streptococci
- viridans species and gamma strep sp.
- enterococci
- gram negative bacilli
- HACEK
- enteric bacilli (IVDA)
- fungi (candida sp.)
- many others
- culture negative IE
what are some complications that arise form infective endocarditis?
- congestive heart failure
- stroke
- infarcts
- glomerulonephritis
- mycotic aneuysms
- abscesses
- local (myocardium)
- distant (embolic seeding)
what is the incidence of bacteremia after periodontal surgery?
60-90%
what is the incidenc eof bacteremia after tooth extraction?
18-85%
what is the incidence of bacteremia after brushing or oral irrigation device?
7-50%
what is the incidence of bacteremia after tonsillectomy?
33-38%
what are the high risk outcomes from infective endocarditis?
- prosthetic heart valves or prosthetic material inserted for cardiac valve repair
- previous infective endocarditis
- congenital heart disease
- cardiac transplant patients who develop valvulopathy
describe the prevention of infective endocarditis
-
prophylactic antibiotics prior to procedures
- prosthetic heart valves
- previous infective endocarditis
- congenital heart diseases
- heart transplant with valvulopathies
- IV or PO regimens at time of procedures
describe the treatment of infective endocarditis
- cure depends upon treatment
- IV therapy (no pills)
- bactericidal regimen
- length of treatment - 2, 4, 6, 8 weeks
- special tests for antibiotic sensitivity
- surgery
- AHA treatment guidelines