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Innovation for reducing blood culture contamination: initial specimen diversion technique
Richard G Patton1, Timothy Schmitt
1Clinical Laboratory, Northwest Hospital and Medical Center/University of Washington Medicine, Department of Pathology, 1550 N. 115th Street, Seattle, WA 98133, USA. rpatton@MagnoliaMT.com
Abstract:
We hypothesized that diversion of the first milliliter of venipuncture blood-the initial specimen diversion technique (ISDT)-would eliminate incompletely sterilized fragments of skin from the culture specimen and significantly reduce our blood culture contamination rate (R). We studied our hypothesis prospectively beginning with our control culture (C) definition: one venipuncture with two sequentially obtained specimens, 10 ml each, the first specimen (M1) for aerobic and the second (M2) for anaerobic media. The test ISDT culture (D) was identical, with the exception that each was preceded by diverting a 1-ml sample (DS) from the same venipuncture. During the first of two sequential 9-month periods, we captured D versus C data (n=3,733), where DMXR and CMXR are R for D and C specimens. Our hypothesis predicted DS would divert soiled skin fragments from DM1, and therefore, CM1R would be significantly greater than DM1R. This was confirmed by CM1R (30/1,061 [2.8%]) less DM1R (37/2,672 [1.4%]; P=0.005), which equals 1.4%. For the second 9-month follow-up period, data were compiled for all cultures (n=4,143), where ADMXR is R for all (A) diversion specimens, enabling comparison to test ISDT. Our hypothesis predicted no significant differences for test ISDT versus all ISDT. This was confirmed by DM1R (37/2,672 [1.4%]) versus ADM1R (42/4,143 [1.0%]; P=0.17) and DM2R (21/2,672 [0.80%]) versus ADM2R (39/4,143 [0.94%]; P=0.50). We conclude that our hypothesis is valid: venipuncture needles soil blood culture specimens with unsterilized skin fragments and increase R, and ISDT significantly reduces R from venipuncture-obtained blood culture specimens.
Insights
Diversion of the initial blood specimen (ISDT) effectively removes skin fragments, significantly reducing blood culture contamination rates. This simple technique improves the accuracy of blood cultures for better patient diagnosis.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Diagnostic Laboratory Medicine
Background:
- Blood culture contamination is a significant issue in clinical diagnostics.
- Contamination can lead to misdiagnosis, unnecessary antibiotic use, and increased healthcare costs.
- Skin flora are a primary source of blood culture contamination during venipuncture.
Purpose of the Study:
- To evaluate the efficacy of the initial specimen diversion technique (ISDT) in reducing blood culture contamination.
- To determine if diverting the first milliliter of blood from venipuncture eliminates skin contaminants.
- To compare contamination rates between standard blood collection and ISDT.
Main Methods:
- Prospective study comparing standard blood cultures (C) with ISDT (D).
- Control cultures involved two sequential 10ml specimens (M1 aerobic, M2 anaerobic).
- ISDT cultures diverted 1ml (DS) before collecting M1 and M2 specimens from the same venipuncture.
Main Results:
- The initial specimen diversion technique (ISDT) significantly reduced contamination in the first specimen (DM1R: 1.4%) compared to standard collection (CM1R: 2.8%; P=0.005).
- Overall contamination rates for ISDT (DM1R: 1.4%, DM2R: 0.80%) were comparable to all diversion specimens (ADM1R: 1.0%, ADM2R: 0.94%), showing consistency.
- ISDT demonstrated a 1.4% reduction in contamination, confirming its effectiveness.
Conclusions:
- The initial specimen diversion technique (ISDT) is a valid and effective method to reduce blood culture contamination.
- Venipuncture needles can introduce unsterilized skin fragments into blood culture specimens, increasing contamination rates.
- ISDT significantly lowers contamination rates in blood cultures obtained via venipuncture.
