Multiple withdrawals from single-use vials: a study on sterility.

Background: Reutilization of single-use vials containing medical drugs is still under discussion. This practice has been adopted as a standard to avoid drug wastage, particularly in developing countries and in the aftermath of disasters. Some studies have assessed sterility of medications stored in single-use vials after utilization as multiple doses; however, most of these were limited to one single drug, included a low number of samples and did not consider an intermediate transfer step from the vial to a disposable syringe. The purpose of this study was to assess microbial contamination of samples withdrawn over three days from disposable syringes prepared from single-use vials.

Methods: A prospective sterility study was conducted. A total of 600 initial samples were prepared from six-hundred 10 mL single-use vials of physiological solution into six-hundred 20 mL disposable syringes. Samples were prepared in three different standard operating rooms, on six different days and by the same operator, using basic sterile technique. All syringes were capped, placed together in a non-sterile steel container, covered with a clean drape and stored in the refrigerator at 4°C under non-sterile conditions. Using basic sterile technique, four samples were withdrawn daily and cultured from each syringe over the next 3 days. Microbial growth was examined on Sabouraud agar and chocolate agar culture media.

Results: A total of 7200 samples were collected and 14,400 cultures were performed. No evidence of microbial growth in any of the culture media plates was found.

Conclusion: This study demonstrated that contents initially stored in single-use vials and subsequently transferred into disposable syringes in an operating room using sterile technique, maintain sterility after 4 withdrawals per day for a total of 3 days.