Disposable syringes are regularly used as final containers for aseptic products prepared within hospital units. SMTL offer the microbiological integrity test from the protocol developed by the NHS Pharmaceutical Quality Assurance committee.

The principle of the test is to fill the syringe system with sterile nutritive media (performed by trained technicians in an aseptic pharmacy unit), the outside of the syringe is then challenged with an actively growing microorganism in order to assess container integrity. The test consists of three parts:

  • The whole immersion test where the whole syringe is submerged in broth.
  • The partial immersion test where the plunger/ barrel interface is challenged.
  • The partial immersion test where the hub/ luer fitting is challenged.


The syringes are pre-incubated to confirm the aseptic fill has been carried out correctly and the contents are sterile.  The challenge organism is Brevundimonas diminuta a small motile rod shaped bacterium, which the syringes are incubated with for 14 days. The integrity of the syringes plunger or hub system is confirmed providing that the broth in all syringes remains free from microbial growth.

SMTL have modified the partial immersion test where the plunger/ barrel interface is challenged to ensure that sufficient broth remains (down the barrel) after the incubation period, the syringe is only filled to half the maximum fill volume.

SMTL have previously published test reports on the use of this test for neuraxial syringes as part of the aborted Welsh contracting process for neuraxial non-Luer products in 2011-2013.

For further information and pricing, please contact the Biological testing team at SMTL.

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