Flashcards in Microbiology - Vosler - Sepsis Deck (23):
What is SIRS? How is it classified? What are the symptoms? What are the value cut-offs?
Systemic inflammatory response syndrome
2 or more of the following:
hyperthermia or hypothermia - Temperature > 38° C or 90 beats/min
tachypnea or hyperventilation - Respiratory rate > 20 breaths/min or PaCO2 (partial pressure of CO2 in the
blood) 12,000 cells/mm3 or 10% immature (band) forms
What differentiates sepsis from severe sepsis from septic shock?
Sepsis - SIRS, which has been induced by an infection
Severe sepsis - defined as having the sepsis criteria plus evidence of organ dysfunction (1 or more):
o Cardiovascular: Systolic BP 1.5 x upper normal.
Septic shock - sepsis-induced hypotension persisting despite adequate fluid resuscitation that requires the use of vassopressors. May include lactic acidosis, oliguria, altered mental status, and acute lung injury
Is SIRS associated with infection?
Sometimes (sepsis) but doesn't have to be: e.g. acute pancreatitis, autoimmune disorder, pancreatitis, vasculitis, thromboembolism,
What is TLR4? What type of bacteria have it?
component of gram negative bacterial cell wall - can also be release as immunologic endotoxin leading to
"cytokine storm" or "gram negative shock"
What is bacteremia? What is the difference between primary and secondary bacteremia?
Cultivatable bacteria in the bloodstream - may or may not be symptomatic or lead to spesis
primary=intravascular without identifiable source of infection (e.g. Catheter Associated Bloodstream Infections, Infective endocarditis, Supprative thrombophlebitis,
secondary = intravascular bacteria with extravascular source of infection (e.g. skin infection, a catheter, pneumonia, or a urinary tract
What are the symptoms of sepsis?
change in mental status, such as reduced alertness or confusion (particularly in the elderly)
fever and shaking/chills or very low body temperature decreased urination
Transient bacteremia - causes?
minutes to hours
can be during dental procedures; after gastrointestinal biopsy; after percutaneous catheterization of the vascular system, bladder, or common bile duct; and after surgical debridement drainage
intermittent bateremia - causes?
bacteremia due to the same microorganism that is detected intermittently in the same patient because of a cycle of clearance and recurrence
caused by abscesses, cholangitis, and focal infections, including pneumonia, osteomyelitis, and spondylodiscitis.
Persistent (continuous) bacteremia - causes?
characteristic of infective endocarditis (IE) and
other intravascular infections, such as vascular-graft infection, a mycotic aneurysm, or an
infected thrombus. Persistent bacteremia also occurs during the early stages of systemic
bacterial infections, such as brucellosis and typhoid fever.
infective endocarditis is what type bacteremia (primary or secondary)?
What are the two biggest risk factors?
What are the three most common associated bacteria?
primary - no documented source of infection and organism is intravascular
IV drug use and heart valve damage
1) Staphylococcus aureus
2)Streptococci of the viridans group
3)coagulase negative Staphylococci
What are the most common bacteria associated with Mycotic (infectious) aneurysm
What is Supprative thrombophlebitis
associated with inflammation
in the setting of bacteremia.
Peripheral vein suppurative
thrombophlebitis occurs most
frequently in the setting of an
intravenous catheter or
peripherally inserted central
venous catheter (i.e. PICC
What is the most sensitive method for detection of bacteremia?
NOTE:normal white blood count does not rule out bacteremia
Why are multiple blood cultures, each containing large
volumes of blood, required to detect bacteremia?
patients with bacteremia are likely to have low quantities of bacteria in the blood (less than one
bacterial cell/mL of blood), even in the setting of severe clinical symptoms
What is a blood culture "set"?
two culture bottles one for aerobic bateria, one for anaerobic bacteria
Each bottle is inoculated with 10 mL of
blood (20 mL total),
What is the protocol for blood sampling prior to beginning antimicrobial therapy?
at least two sets of blood cultures taken from separate
venipuncture sites should be obtained with minutes of eachother. A total of three blood culture sets over 24
hours is usually adequate (more volume – better likelihood for detection)
One set: 80% of bacteremia’s detected
Two sets: 90% of bacteremia’s detected
Three sets: 99% of bacteremia’s detected
Does having a fever at the time of blood culture collection increases the likelyhood of detecting bacteremia?
NO. Fever is neither sensitive nor specific for presence of bacteria.
What is the most common source of contamination for blood cultures? What are the agents?
What are the consequences of contamination?
normal skin flora
Frequent skin contaminants include coagulase negative staphylococci,
Corynebacteria (a.k.a. Diptheroids), and Propionobacteria.
bacterial skin flora can cause systemic disease. contamination can make it difficult to distinguish
between false positive results and true infection
1) Where does primary bacteremia arise from?
a. An endovascular source
b. The lung
c. The liver
d. The gastrointestinal tract
What type of bacteremia may result when a procedural manipulation of a
particular body site that is colonized by normal flora occurs?
a. Continuous bacteremia
b. Intermittent bacteremia
c. Transient bacteremia
What is the most common clinical manifestation associated with continuous
Which statement best describes SIRS (Systemic Inflammatory Response
a. An inflammatory response at the source / site causing bacteremia.
b. An inflammatory response that only arises in response to bacteremia.
c. An inflammatory response that occurs only in the intravascular space.
d. An abnormal generalized inflammatory reaction in organs remote from the