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Contamination of blood cultures during venepuncture: fact or myth?
E Shahar1, B S Wohl-Gottesman, L Shenkman
1Department of Medicine C, Meir General Hospital, Sapir Medical Center, Kfar-Saba, Israel.
Abstract:
Contamination of blood cultures is believed to occur mainly during the venepuncture procedure. Consequently, meticulous preparation of the venepuncture site is widely recommended. To determine whether the contamination rate is indeed affected by the quality of the antiseptic procedure at the venepuncture site, 181 paired cultures were collected from 176 patients during a 6-month period after either strict antiseptic cleansing of skin with alcohol followed by povidone-iodine, or after brief disinfection with alcohol alone. The contamination rate was not influenced by the antiseptic procedure, and corresponded to the accepted percentage reported in most other studies. Eight false positive cultures (4.4%) were obtained after strict antisepsis of the skin and 6 (3.3%) after short simple cleansing with alcohol (P = 0.39). Our results suggest that contamination of blood cultures may not be related to the venepuncture procedure--regardless of the antiseptic technique used--but may be due to later stages of laboratory handling and processing of the specimens. Review of the literature has provided further indirect evidence to support this conclusion.
Insights
Blood culture contamination is not affected by skin antisepsis quality. Results suggest contamination may stem from laboratory handling, not venepuncture site preparation.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
Background:
- Blood culture contamination is a significant issue in clinical diagnostics.
- Meticulous venepuncture site preparation is standard practice to minimize contamination.
Purpose of the Study:
- To investigate the impact of different antiseptic procedures on blood culture contamination rates.
- To determine if venepuncture site disinfection quality influences false positive results.
Main Methods:
- 181 paired blood cultures were collected from 176 patients over 6 months.
- Cultures were compared based on two skin antisepsis protocols: strict (alcohol + povidone-iodine) vs. brief (alcohol alone).
Main Results:
- No significant difference in contamination rates was observed between the two antiseptic procedures (4.4% vs. 3.3%, P = 0.39).
- The contamination rate was within accepted ranges reported in other studies.
Conclusions:
- The quality of skin antisepsis during venepuncture does not appear to significantly affect blood culture contamination rates.
- Findings suggest that contamination may originate from post-venepuncture laboratory handling and processing rather than the venepuncture procedure itself.