Bacteremia vs contaminated blood cultures: Difference between revisions
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==Background== | ==Background== | ||
*Staphylococcus aureus and Candida sp. isolated from the blood should never be considered a | *Staphylococcus aureus and Candida sp. isolated from the blood should never be considered a contaminant<ref>Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp</ref> | ||
==Suggestive of | ==Suggestive of Contamination<ref>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 Staphylococcal species | ##coagulase-negative Staphylococcal species | ||
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##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 | ==Risk Factors for Bacteremia<ref>Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp</ref>== | ||
*Advanced age | *Advanced age | ||
*Corticosteroids | *Corticosteroids | ||
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*Parenteral nutrition | *Parenteral nutrition | ||
==Contamination Rates for Specific | ==Contamination Rates for Specific Organisms<ref>Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp</ref>== | ||
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Revision as of 06:56, 22 April 2014
Background
- Staphylococcus aureus and Candida sp. isolated from the blood should never be considered a contaminant[1]
Suggestive of Contamination[2]
- Typical commensal organisms of the skin flora in the abscence of an intravenous catheter
- coagulase-negative Staphylococcal species
- certain Streptococci
- Gram-positive bacilli
- Only 1 out of 2 or more blood cultures are positive
- Most commonly used 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)
- 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[3]
- 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[4]
| 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
- ↑ Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
- ↑ Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
- ↑ Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
- ↑ Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp