BACKGROUND Blood culture contamination leads to inappropriate or unnecessary antibiotic use. However, practical guidelines are inconsistent about the routine use of sterile gloving in collection of blood for culture.

OBJECTIVE To determine whether the routine use of sterile gloving before venipuncture reduces blood culture contamination rates.

DESIGN Cluster randomized, assessor-blinded, crossover trial (ClinicalTrials.gov registration number: NCT00973063).

SETTING Single-center trial involving medical wards and the intensive care unit.

PARTICIPANTS 64 interns in charge of collection of blood for culture were randomly assigned to routine-to-optional or optional-to-routine sterile gloving groups for 1854 adult patients who needed blood cultures.

INTERVENTION During routine sterile gloving, the interns wore sterile gloves every time before venipuncture, but during optional sterile gloving, sterile gloves were worn only if needed.

MEASUREMENTS Isolates from single positive blood cultures were classified as likely contaminant, possible contaminant, or true pathogen. Contamination rates were compared by using generalized mixed models.

RESULTS A total of 10 520 blood cultures were analyzed: 5265 from the routine sterile gloving period and 5255 from the optional sterile gloving period. When possible contaminants were included, the contamination rate was 0.6% in routine sterile gloving and 1.1% in optional sterile gloving (adjusted odds ratio, 0.57 [95% CI, 0.37 to 0.87]; P = 0.009). When only likely contaminants were included, the contamination rate was 0.5% in routine sterile gloving and 0.9% in optional sterile gloving (adjusted odds ratio, 0.51 [CI, 0.31 to 0.83]; P = 0.007).

LIMITATION Blood cultures from the emergency department, surgical wards, and pediatric wards were not assessed.

CONCLUSION Routine sterile gloving before venipuncture may reduce blood culture contamination.