Septicemia

What are the 3 risk factors/ targets of sepsis?

immunocompromised/severely ill patients

those overusing broad-spectrum antibiotics

those undergoing invasive procedures (organ transplant, catheters, extended surgery)

What are some pathogens that can cause sepsis? (6)

Staph aureus & coag-neg staph

Beta hemolytic strep

S. pneumonie & viridans

enterococcus

e. coli & other enterics

yeast (50% candida albicans)

What is the difference between bacteremia and septicemia?

bactermia is the presence of bacteria in blood, septicemia is the disease caused by bacteria in blood

What are the 4 classifications of bacteremia/septicemia?

by site of origin

by microbiology (causative agent)

by place of acquisition

by duration

What is primary vs secondary bacteremia? (By site of origin)

primary: endovascular source (infected cardiac valve or intravenous catheter)

secondary: extravascular source such as lungs

What are the 2 settings where septicemia can be acquired? (by place of acquisition)

community-acquired and nosocomial

What are the 3 distinguished durations of septicemia?

transient (dental, colonoscopic)

intermittent (miningococcemia, pneumonia)

continuous (endocarditis)

What is the difference between extravascular and intravascular sepsis?

extravascular: originating outside the cardiovascular system (CV) and entering bloodstream via lymphatic system

intravascular: originating in the CV system

What are the sources of extravascular and intravascular sepsis? (4 extra, 2 intra)

extravascular: GU tract 25%, Resp tract 20%, Abcesses/Wounds 15%, others 35%

intravascular: infective endocarditis or intravenous, catheter-associated)

What are the 4 examples of the effects of sepsis?

hypotension or shock

disseminated intravascular coagulation (DIC)

major organ system failure

possible clue to undiagnosed cancer

What are the 5 critical issues (important aspects) of handling blood cultures?

proper specimen collection

rapid detection of pathogen

astute gram stain evaluation & timely/appropriate reporting of results

culture evaluation/identification

susceptibility testing & rapid detection of important resistance

What are the 4 steps for preparing the draw site? (proper specimen collection)

cleanse w/ 70% alcohol

apply 1-10% iodine. let dry thoroughly

draw blood w/out touching draw site

cleanse draw site w/ alcohol again to remove iodine

How many blood culture specimens should be collected per 24 hours?

2-3 specimens, each >3 hours apart

What is the appropriate volume that should be collected for a blood culture?

20 mL

10 mL from 2 separate venipuncture sites (using 2 separate needles/syringes)

What is the time frame and temperature in which a blood culture should be transported?

room temp within 2 hours

What is the bacterial load (bugs/mL) in adults vs. children who have septicemia? And what is the minimum volume of blood required to detect septicemia?

adults: <30 microbes/mL. 10 mL minimum

childen: up to 10³ microbes/mL. any volume should be cultured (1 mL per year old)

What is the anticoagulant additive in blood culture media? What is the ratio of blood to broth medium?

Sodium polyanethol sulfonate (SPS 0.03%)

1 blood 5 broth

What is added to blood culture media to absorb inhibitors? What may be required to support obligate anaerobes?

resin or charcoal

venting (control flow of gases)

What are the 3 manual blood culture systems?

conventional (visual inspection)

Septi-Chek (biphasic media)

Isolator (lysis-centrifugation system)

What is the advantage & disadvantage of the Septi-Chek?

advantage: self-subculturing

disadvantage: poor anaerobe recovery

What are the 4 pros of automation for blood culture detection?

saves time/labor

continuous shaking/monitoring for positives

variety of media formulations

barcode driven & interfaced w/ LIS

What is a primary challenge when evaluating/identifying a blood culture?

Whether the isolate is a skin contaminant or not

In what time frame are most blood cultures positive for septicemia? What would a pathogen vs a contaminant look like in blood culture detection?

72 hours

multiple bottles would be positive, vs 1 bottle in the case of a contamination

what are some common contaminate species?

diphtheroids and coag neg staph

How long are are cultures kept for slow-growers?

up to 4 weeks