Defective Plastic Bottles, Improper Storage Temperature, and the Worldwide Fusarium Keratitis Epidemic of 2004-2006

Purpose: To demonstrate the effects of container properties and storage temperatures on the ability of a contact lens solution, previously implicated in the Fusarium keratitis epidemic of 2004-2006, to inhibit growth of Fusarium species. A 2006 FDA inspection indicated that the manufacturer had failed to regulate storage and transport temperatures of its products. Bullock et al [Arch Ophthalmol 2008;126(11):1493-1498] later demonstrated that fungistatic failure occurred when the solution in its plastic bottle was exposed to prolonged temperature elevation, whereas boiling the solution in a glass tube did not degrade its fungistatic capability, suggesting that the plastic container, in combination with heat, could have been detrimental.

Methods: The solution was divided into six aliquots and stored separately for four weeks at room temperature (RT), 42oC, and 60oC, in both their original plastic bottles and similarly-sized glass containers, then tested in triplicate for their ability to inhibit the growth of seven Fusarium isolates associated with the epidemic.

Results: When stored in glass containers, the solution demonstrated no fungistatic deterioration at all three temperatures. However, when the original plastic container was stored at 60oC, a highly statistically significant fungistatic deterioration was noted compared to those stored in plastic at either RT (P=4.0x10-7) or 42oC (P=2.10x10-6).

Conclusions: When stored in its original plastic (as opposed to a glass) container and exposed to prolonged temperature elevation (60oC), the contact lens solution implicated in the Fusarium keratitis epidemic of 2004-2006 loses its in vitro fungistatic capability. The temperature required for fungistatic failure is >42oC and ≤60oC.