Bacteremia vs contaminated blood cultures: Difference between revisions
 
(6 intermediate revisions by 3 users not shown)
Line 3: Line 3:


==Suggestive of Contamination<ref name="perez">Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp</ref>==
==Suggestive of Contamination<ref name="perez">Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp</ref>==
#Typical commensal organisms of the skin flora '''in the abscence of an intravenous catheter'''
*Typical commensal organisms of the skin flora '''in the abscence of an intravenous catheter'''
##Coagulase-negative [[Staphylococcus]] species
**Coagulase-negative [[Staphylococcus]] species
##Certain [[Streptococci]]
**Certain [[Streptococci]]
##[[Gram-Positive]] bacilli
**[[Gram-Positive]] bacilli (rods)
#Only 1 out of 2 or more blood cultures are positive
*Only 1 out of 2 or more blood cultures are positive
##When positive for coagulase-negative [[Staphylococcal Species]]
**When positive for coagulase-negative [[Staphylococcal Species]]
#[[Antibiotic Susceptibility Pattern]] of one organism is different from the pattern of the other organisms in the same or subsequent set of cultures (as long as the organisms are of the same species)
*[[Antibiotic Susceptibility Pattern]] of one organism is different from the pattern of the other organisms in the same or subsequent set of cultures (as long as the organisms are of the same species)
##For example, if 2 sets of blood cultures are both positive for Staphylococcus epidermidis but one set is sensitive to a particular antibiotic while the other set is resistant to the same antibiotics, both sets are likely contaminated
**For example, if 2 sets of blood cultures are both positive for [[Staphylococcus epidermidis]] but one set is sensitive to a particular antibiotic while the other set is resistant to the same antibiotics, both sets are likely contaminated


==Risk Factors for Bacteremia<ref name="perez"></ref>==
==Risk Factors for Bacteremia<ref name="perez"></ref>==
Line 23: Line 23:
*Intravenous drug use
*Intravenous drug use
*Loss of skin integrity
*Loss of skin integrity
*Malnutrition and hypoalbuminemia
*Malnutrition and [[hypoalbuminemia]]
*Neutropenia
*Neutropenia
*Parenteral nutrition
*Parenteral nutrition
Line 32: Line 32:
! Organism !! False positives
! Organism !! False positives
|-
|-
| Bacillus spp. || >90%
| [[Bacillus]] spp. || >90%
|-
|-
| Coag-negative [[Staphylococcus]] spp. || >90%
| Coag-negative [[Staphylococcus]] spp. || >90%
|-
|-
| Propionibacterium spp. || >90%
| [[Propionibacterium]] spp. || >90%
|-
|-
| Corynebacterium spp. || >80%
| [[Corynebacterium]] spp. || >80%
|-
|-
| [[Viridans-Group Streptococci]] || 50%
| [[Viridans-Group Streptococci]] || 50%
|-
|-
| Clostridium spp. || 40%
| [[Clostridium]] spp. || 40%
|-
|-
| [[Staphylococcus aureus]] spp. || 25%
| [[Staphylococcus aureus]] spp. || 25%
|-
|-
| Enterococcus spp. || 15%
| [[Enterococcus]] spp. || 15%
|}
|}


Line 52: Line 52:
*[[Microbiology (Main)]]
*[[Microbiology (Main)]]


==Sources==
==References==
<references/>
<references/>
[[Category:ID]]

Latest revision as of 15:09, 21 May 2020

Background

Suggestive of Contamination[1]

  • Typical commensal organisms of the skin flora in the abscence of an intravenous catheter
  • Only 1 out of 2 or more blood cultures are positive
  • Antibiotic Susceptibility Pattern of one organism is different from the pattern of the other organisms in the same or subsequent set of cultures (as long as the organisms are of the same species)
    • For example, if 2 sets of blood cultures are both positive for Staphylococcus epidermidis but one set is sensitive to a particular antibiotic while the other set is resistant to the same antibiotics, both sets are likely contaminated

Risk Factors for Bacteremia[1]

  • Advanced age
  • Corticosteroids
  • Immunosuppressing medications (transplant patients, rheumatologic diseases, etc)
  • Chronic liver disease
  • Chronic renal failure (especially if on hemodialysis)
  • Hematological malignancies
  • HIV infection
  • Intravenous catheters
  • Intravenous drug use
  • Loss of skin integrity
  • Malnutrition and hypoalbuminemia
  • Neutropenia
  • Parenteral nutrition

Contamination Rates for Specific Organisms[1]

Organism False positives
Bacillus spp. >90%
Coag-negative Staphylococcus spp. >90%
Propionibacterium spp. >90%
Corynebacterium spp. >80%
Viridans-Group Streptococci 50%
Clostridium spp. 40%
Staphylococcus aureus spp. 25%
Enterococcus spp. 15%

See Also

References

  1. ↑ 1.0 1.1 1.2 1.3 Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
Retrieved from "https://www.wikem.org/w/index.php?title=Bacteremia_vs_contaminated_blood_cultures&oldid=256073"