Reallocation of sterile injectable preparations: what is the microbiological risk ?

Introduction
The reallocation of non-administered injectable anticancer preparations has progressively emerged as an alternative to disposal and thus contributes to reducing drug waste. Performing reallocation within an isolator and implementing analytical testing have been identified as risk-reduction measures in our unit. The aim of this study was to assess the risk of microbiological contamination of non-administered preparations returned from clinical wards and its potential impact on the microbiological control of isolators.

Materials and Methods
An experimental study simulating reallocation within an isolator was conducted. Twelve infusion bags filled with nutrient broth were stored for 24 hours in an uncontrolled environment under four conditions (n = 3 bags per group) : maintenance in intact sterile packaging (C1) ; opening of the sterile packaging without handling the infusion bag (C2) ; removal of the infusion bags from their sterile packaging and handling with gloves (C3) or without gloves (C4) followed by repackaging and closure. The infusion bags were then successively reintroduced into the isolator by category and relabelled to simulate reallocation. A 5 mL sample of the contents of each infusion bag (n = 12) was collected and the external surface and Luer-lock connector of each infusion bag were sampled using a wet eSwab^® followed by inoculation onto Tryptic Soy Agar (n = 24). The surfaces and sampling method had been previously validated. Environmental samples from the isolator (gloves and work surface) were collected using Count-Tact^® contact plates (n = 36). An air sampler using an impaction method was activated upon the introduction of each group of infusion bags (n = 4). All samples were incubated for 72 hours at a temperature > 30°C. The broth was visually inspected and colonies on agar plates were counted.

Results
No contamination of the contents of the infusion bags or of the isolator environment was detected. Surface contamination was observed on the external surface of the third infusion bag in group C3, more than 48 hours after incubation.

Discussion/Conclusion
The results suggest a limited microbiological risk associated with reallocation under the studied conditions. However, the limited sample size and the experimental nature of the study should be taken into consideration. This work supported the reallocation within isolators of non-administered preparations that had remained outside a controlled environment for less than 24 hours and had been kept in their sterile packaging, provided that strict acceptance criteria and rigorous traceability were implemented.

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