Centralization of vitamin-lipid blend production: validation of membrane filtration for sterility testing

Context
Vitamin-Lipid Blend (VLB) are sterile preparations used for nutritional supplementation for premature newborns. Currently, VLB syringes are prepared by .nurses within the care units. As part of an effort to improve their safety and their quality, the Pharmaceutical Technology department was asked to centralize the production of these syringes.
This standardization requires the implementation of an appropriate microbiological control. The objective of this study is to validate a membrane filtration sterility test method in conformity with the European Pharmacopoeia (EP) (11th ed., Chapter 2.6.1)

Method
The experiments were conducted by inoculating 6 microbial strains defined by the EP (C. sporogenes, P. aeruginosa, S. aureus, A. brasiliensis, B. subtilis, and C. albicans) at 50 CFU, with 3 repetitions performed by 3 different operators on 3 different days, and including positive and negative controls for each test series in order to validate the parameters of sterility, fertility, and applicability.
The cultures were incubated for 14 days at 25°C and 35°C depending on the medium used (respectively casein-soy broth and thioglycolate broth), with readings taken from the canisters on Day 1, Day 3, Day 5, Day 7, and Day 14.

Results
On average, the microbial strain cultures turned positive within 3 days. After 5 days, all cultures tested positive, and growth rates were equivalent between the VLB canisters and the positive controls. The negative controls showed no microbial contamination after 14 days of incubation. The identification of the microorganisms present in the culture mediums was consistent with the inoculated strains.

Discussion - Conclusions
The various parameters tested validated the use of membrane filtration to check the sterility of VLB syringes.
However, this technique has limitations and requires a prolonged incubation time that is not well suited to the limited stability (7 days) of VLBs, which necessitates early release for daily use. It therefore seems worthwhile to explore the use of alternative methods for daily VLB testing.

Mesh terms: pharmaceutical preparations, parenteral nutrition, microbiological techniques

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