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Updated: Jun 25, 2026
Intravitreal Injection and Quantitation of Infection Parameters in a Mouse Model of Bacterial Endophthalmitis
Published on: February 6, 2021
Bacterial contamination of needle points after intravitreal injection
Martin Nentwich1, Yazmin Yactayo-Miranda, Steffen Weimann
1Department of Ophthalmology, Ludwig-Maximilian University, Munich - Germany. Martin.Nentwich@med.uni-muenchen.de
Purpose:
Evaluation of the magnitude and pattern of bacterial contamination of needle points with conjunctival bacteria during the intravitreal injection. Analysis of the efficacy of preinjection prophylaxis.
Methods:
A total of 550 intravitreal injections were done in 414 patients (n=425 eyes). A total of 289 patients were injected once, while 125 patients received several injections. Before the intravitreal injection in the operation room, the following standard preoperative preparation of the eye-10% povidone iodine scrub on the eyelids, eyelashes, and forehead and irrigation of the conjunctival sac with 1% povidone iodine-was carried out. Immediately after the injection, the needle points were rinsed three times in thioglycolate broth, which was cultured at 35 degrees C for 5 days afterwards. As a negative control, 200 sterile unused needle points were treated the same way.
Results:
Only 2 out of 550 (0.36%) needle points were contaminated after intravitreal injection. In sensitivity testing, the isolated Staphylococcus epidermidis and Corynebacterium sp did not show multidrug resistance. All 200 unused needle points proved to be sterile after 5 days of cultivation.
Conclusions:
Contamination of needle points is minimal after iodine irrigation prophylaxis before intravitreal injection. Therefore, we recommend this prophylaxis technique before intravitreal injections. The low incidence of contaminated needle points, however, shows that there still is a risk of bacteria entering into the eye during injection.
