Ocular Microbiology and Immunology Group
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2015 OMIG Abstract 4

Is Benzalkonium Chloride (BAK) Effective against Adenovirus?
EG Romanowski, KA Yates, RMQ Shanks, RP Kowalski.
The Charles T. Campbell Laboratory, UPMC Eye Center, Ophthalmology and Visual Sciences Research Center, Eye and Ear Institute, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA

Purpose: Benzalkonium chloride (BAK) is a common preservative used in ophthalmic medications. The goal of the current study was to determine whether BAK, at concentrations contained in ophthalmic medications, is effective in reducing titers of common ocular adenovirus (Ad) types. 
Methods: The direct inactivating activity of BAK was determined in duplicate trials by incubating high titer stocks of clinical isolates of Ad3, Ad4, Ad5, Ad7a, Ad8, Ad19, and Ad37 ATCC, with 0.001%, 0.003%, 0.005%, 0.01% BAK (concentrations found in ophthalmic medications) and a higher BAK concentration (0.1%) and control media for 1h at 33^oC. Following incubation, standard plaque assays were performed on the reaction mixtures to determine the Ad titers after BAK or control treatment. Ad titers were Log₁₀ converted and Log₁₀ reductions in titers from the control were calculated.
Results: A BAK concentration of 0.1% was virucidal (> 3 log₁₀ decrease) for Ad3, Ad5, Ad7a, Ad19, and Ad37. 0.1% BAK reduced titers >1 Log₁₀ but < 3 Log₁₀ for Ad4 and Ad8. A >1 log₁₀ decrease was demonstrated for BAK concentrations of 0.003%, 0.005% and 0.01% for Ad5 only. A <1 log₁₀ decrease was noted for 0.001% BAK against all adenovirus types.
Conclusions: BAK, at concentrations used in common ophthalmic medications, demonstrated variable efficacy in reducing titers of the Ad types tested. However, 0.1% BAK was effective in reducing titers of all of the Ad types tested. BAK at concentrations used in common ophthalmic medications appears not to be consistently effective as an agent against Ad, but higher concentrations should be further investigated as a topical treatment for adenoviral ocular infections.

Disclosure Code: N

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