Related Experiment Video
Updated: Aug 18, 2026
Ocular Therapeutic Delivery and Advanced Tissue Retrieval in Adult Rats
Published on: May 23, 2025
Microbiologic studies of multiple-dose containers of triamcinolone acetonide and lidocaine hydrochloride
Rodney S Bucher1, Mark W Johnson
1Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, USA.
Purpose:
Reports of high endophthalmitis rates following intravitreal triamcinolone acetonide (TA) injection have raised concerns about safety. One possible risk factor is the use of multiple-dose containers. The purpose of this study was to determine whether there is a substantial risk of contamination of multiple-dose containers.
Methods:
Microbiologic Challenge Study: Suspensions of a known quantity of several microorganisms were placed in samples of TA to determine whether the preservative, benzyl alcohol 0.99%, is rapidly bacteriocidal. Simulated Clinical Use Study: After ten days of simulated clinical use of multiple-dose containers of TA and lidocaine hydrochloride 4%, samples were cultured. Additionally, samples from lidocaine containers in actual clinical use were cultured.
Results:
Microbiologic Challenge Study: Four of five challenge organisms demonstrated moderate growth, even after 24 hours of exposure to the benzyl alcohol preservative. Simulated Clinical Use Study: Simulated clinical use of multiple-dose containers of TA and lidocaine did not result in contamination, nor did actual clinical use of multiple-dose lidocaine containers.
Conclusions:
No culture-proven contamination of multiple-dose containers in simulated or actual clinical use was found. However, TA suspension is capable of harboring viable bacterial and fungal pathogens. The use of multiple-dose containers of triamcinolone for intravitreal injections is therefore discouraged.
Insights
Multiple-dose containers of triamcinolone acetonide (TA) showed no contamination in simulated use, but TA suspension can harbor pathogens. Intravitreal injections using these multi-dose vials are discouraged due to potential endophthalmitis risks.
Area of Science:
- Ophthalmology
- Microbiology
Background:
- Intravitreal triamcinolone acetonide (TA) injections are associated with high endophthalmitis rates.
- The use of multiple-dose containers for TA injections is a potential risk factor for contamination.
Purpose of the Study:
- To assess the risk of microbial contamination in multiple-dose containers of triamcinolone acetonide (TA).
- To evaluate the efficacy of the preservative benzyl alcohol in TA suspensions.
Main Methods:
- A microbiologic challenge study assessed the bacteriocidal properties of benzyl alcohol (0.99%) in TA.
- A simulated clinical use study cultured multiple-dose TA and lidocaine containers after 10 days.
- Samples from lidocaine containers in actual clinical use were also cultured.
Main Results:
- Four of five tested microorganisms showed moderate growth in TA with benzyl alcohol, indicating incomplete bacteriocidal activity.
- No contamination was detected in multiple-dose TA or lidocaine containers during simulated clinical use.
- No contamination was found in lidocaine containers from actual clinical use.
Conclusions:
- While simulated use showed no contamination, triamcinolone acetonide (TA) suspension can support bacterial and fungal growth.
- The study discourages the use of multiple-dose TA containers for intravitreal injections due to potential pathogen harboring.
- Further research into safe practices for intravitreal medication delivery is warranted.
