Bacterial infections of the circulatory system Flashcards
Is bacteremia required for sepsis?
No
Systemic inflammatory response syndrome (SIRS) is two or more of what conditions?
- Fever or hypothermia 2. Tachypnea 3. Tachycardia 4. Abnormal WBC count (leukocytosis or leukopenia)
What is severe sepsis?
Sepsis with one or more signs of organ failure
What is septic shock?
Severe sepsis + hypotension
What is refractory septic shock?
Septic shock that lasts for 1 hour and does not respond to fluid and pharmacologic treatment
What is multiorgan failure?
Dysfunction of one or more organs + disseminated intravascular coagulation (DIC)
What leads to DIC?
- Early cytokines in systemic inflammation 2. IL-6 –> tissue factor –> DIC
What initiates septic shock?
LPS, lipid A, TSST-1, polysaccharides of C. albicans, teichoic acid of staph, capsule of S. pneumo
What is the pathophysiology of LPS-induced sepsis?
- LPS binds to CD14 and TLR4 on phagocytes / APCs 2. Immune system activated 3. Inflammation / septic shock via TNFa, IL-1, IL-6
What is the gram stain for staph aureus?
Gram positive
What is the catalase test for staph aureus?
Catalase positive
What is the coagulase test for staph aureus?
Coagulase positive
How does strep TSS differ from staph TSS?
- Strep TSS is usually accompanied by bacteremia 2. Strep TSS may also include necrotizing fasciitis
What virulence factors are responsible for the clinical manifestations of strep TSS?
SpeA and SpeC
During septic shock what percentage of patients will be positive for blood cultures?
40-70%
What are the localized sites of infection for staph aureus and strep pyogenes?
Generalized erythroderma (looks like sunburn)
What is the most common cause of acute endocarditis?
Staph aureus
What is the most common cause of subacute endocarditis?
Viridans strep
What are the clinical features of acute endocarditis?
- High fever 2. Rapid damage to heart 3. Death within weeks
What are the clinical features of subacute endocarditis?
- Low fever 2. Slow damage to heart 3. Death over weeks to months 4. Skin lesions (splinter hemorrhages, Roth spots, Janeway lesions, Osler nodes)
What are the viridans strep species associated with subacute endocarditis?
S. mitis and S. salivarius
What is the hemolysis pattern for viridans strep?
Alpha or gamma
What is the treatment for subacute bacterial endocarditis?
Penicillin + aminoglycoside (vancomycin for resistant strains)
Viridans strep species are resistant to what agent?
Optochin
What are the two main predisposing causes of infective endocarditis?
- Susceptible cardiovascular substrate 2. Source of bacteremia
What are the major criteria for bacterial endocarditis?
- Positive blood culture with typical organism 2. Evidence of endocardial involvement
What are the minor criteria for bacterial endocarditis?
- Predisposition 2. Fever 3. Vascular phenomena 4. Immunologic phenomena 5. Microbiologic evidence
What is the treatment for bacterial endocarditis?
Aggressive and prolonged antimicrobial therapy
