Unit 2 - Blood Stream Infections Flashcards
what are factors contributing to increasing incidence of sepsis?
- increasingly aggressive oncological chemotherapy and radiation therapy
- widespread use of corticosteroid and immunosuppressive therapies for organ transplantation and/or inflammatory diseases
- increasing survival of patients predisposed to sepsis (neonates, elderly, diabetics, cancer, major organ failure, granulocytopenia)
- increased use of invasive devices (surgical prostheses, inhalation equipment, IV and urinary catheters)
- indiscriminate use of antimicrobial drugs that create conditions for overgrowth, colonization, and subsequent infection by aggressive, antimicrobial-resistant pathogens
mortality of sepsis?
varies according to degree of pathologic derangement and presence of documented infection
- SIRS up to 7%
- sepsis 16-28%
- septic shock 45-65%
what are complications from sepsis?
19% CNS dysfunction 2-8% ARDS 12% liver failure 9-23% acute renal failure 8-18% DIC
what are complications from septic shock?
18% ARDS
38% DIC
50% ARF
what is the definition of infection?
presence of microorganisms in a normally sterile site
-not the same as colonization
what is the definition of colonization?
presence of microorganisms on an epithelial surface
-not the same as infection
what is the definition of bacteremia?
cultivatable bacteria in the bloodstream
- may be transient or associated with sepsis and organ failure
- may be primary (w/o identifiable source) or secondary (with intravascular or extravascular focus of infection)
what is the definition of septicemia?
same as bacteremia, but implies presentation of clinical manifestations associated with the bacteria in bloodstream
what is the definition of sepsis?
confirmed or clinical evidence of infection plus evidence of systemic response
- SIRS is called sepsis in American consensus
- with the exceptions of leukopenia and hypothermia, these changes are among the body’s normal systemic responses and don’t imply poor prognosis
what is the definition of SIRS?
systemic inflammatory response syndrome (whole body, without proven source of infection)
- systemic response to a wide range of stresses; need 2+ of the following:
- -temp > 38 C or < 36 C
- -HR > 90bpm
- -RR > 20, or PaCO2 < 32 mmHg
- -WBC > 12K, 10% bands
what is severe sepsis?
sepsis associated with dysfunction of organ(s) distant from the site of infection, plus 1+ of the following:
- hypotension (reversible by administering fluids)
- confusion
- oliguria
- hypoxia (not explained by primary respiratory disease)
- metabolic (lactic) acidosis)
- DIC
- hepatic dysfunction (not explained by primary liver disease)
also known as sepsis syndrome
what is the definition of septic shock?
sepsis-associated hypotension associated with lactic acidosis or organ hypoperfusion
- cannot be reversed by IV fluids
- if lasts for > 1 hr and doesn’t respond to vasopressor administration, use the term “refractory septic shock”
what happens if you have SIRS with proof of bloodstream infection?
it’s called sepsis
what are complications of SIRS?
results in multiple organ dysfunction syndrome
what are causes of SIRS other than BSI?
- severe trauma
- surgical complication
- burns
- acute pancreatitis
- immunodeficiency (like AIDS)
how is SIRS related to cytokine storm?
subset of cytokine storm/dysregulation
describe the role of TLRs in mediating SIRS?
- TLR4 - plays the most critical role in mediating severity, recognizing and transmitting LPS signal to cell interior
- -engagement of TLR4 leads to release of proinflammatory mediators (TNF-alpha, IL-1, IL-6) in cytokine storm
- TLR2 - peptidoglycan and lipoteichoic acid
explain what occurs in endotoxic (G-) shock
excessive release of cytokines, often triggered by LPS of G- bacteria
-diffuse intravascular coagulation with consequent defective clotting, changes in vascular permeability, loss of fluid into tissues, fall in BP, circulatory collapse, hemorrhagic necrosis
