Multidose medication vial sterility: an in-use study and a review of the literature.

Contaminated multiple-dose medication vials (MDV) have been implicated in transmission of bacterial infections. It has been suggested that MDV be discarded after 24 hours or even after a single use. At our hospital, we cultured 1,223 weekly samples from 863 MDV in-use over a three-month period. Medications included xylocaine, insulin, heparin, immunizations, and miscellaneous agents. None of the samples was culture-positive. The duration of use was 9.5d (median), 18d (mean), and 1-402d (range) with 13% of vials in-use for more than 30 days. The mean duration of use was significantly shorter for medicine wards, emergency room, and outpatient clinics than for surgery and ob-gyn wards (p less than 0.05). Heparin and insulin MDV were in-use for significantly less time than xylocaine and miscellaneous agents (p less than 0.05), and insulin MDV were more regularly dated (p = 0.001). The percentage of undated MDV declined significantly by month during the study (p = 0.003). These results lend support to our current guideline that MDV should be dated upon opening and that, unless visible or suspected contamination occurs, vials are discarded either when empty or at the manufacturer's expiration date.