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Updated: Jun 7, 2026
Intravitreal Injection and Quantitation of Infection Parameters in a Mouse Model of Bacterial Endophthalmitis
Published on: February 6, 2021
Bacterial contamination of needles used for intravitreal injections: a prospective, multicenter study
Jay M Stewart1, Sunil K Srivastava, Anne E Fung
1University of California, San Francisco, Department of Ophthalmology, San Francisco, California, USA. stewartj@vision.ucsf.edu
Purpose:
To determine the incidence of bacterial contamination of needles used for intravitreal injections.
Methods:
Patients undergoing intravitreal injections were enrolled prospectively. No pre-injection antibiotics were administered. Following povidone-iodine irrigation, conjunctival cultures were taken and the injection was performed. The needle was cultured. A dry control needle was exposed to the surgical field and cultured.
Results:
No patients developed endophthalmitis. Eighteen injection needles (18%) yielded positive bacterial growth. The most commonly encountered organisms were Propionibacterium acnes (n = 8) and Staphylococcus epidermidis (n = 6). Four control needles showed positive growth, in 2 cases with the same organism as a matching positive used needle. The difference between contamination rates of used and control needles was significant (p = .002, McNemar's test).
Conclusions:
Bacterial contaminants are present on a substantial proportion of needles. Since the needle contacts both the ocular surface and the vitreous, it is possible that inoculation of the vitreous cavity occurs in such cases.
