Differential Antimicrobial Efficacy of Multipurpose Solutions against Acanthamoeba Trophozoites

Abstract

Significance: This investigation examines the effectiveness of several common contact lens solutions in the disinfection of Acanthamoeba, which causes a serious eye infection most often resulting from dysfunctional or improper use of contact lens products.

Purpose: Acanthamoeba keratitis is an eye infection caused by a free-living amoeba, which can lead to extensive corneal damage and frequently blindness. Acanthamoeba keratitis is linked with contact lens use combined with noncompliance with contact lens care cleaning regimens. The patient's choice and use of multipurpose solutions (MPSs) continue to be a risk factor for Acanthamoeba keratitis. Thus, it is critical that the Acanthamoeba disinfection efficacy of the popular MPSs be determined. Here we compare the efficacy of seven major MPSs on the global market.

Methods: Using standard methods of Acanthamoeba disinfection and quantification, Acanthamoeba ATCC 30461, 30868, 50370, and 50676 trophozoites were inoculated into each MPS and held for the manufacturer's recommended disinfection time. Acanthamoeba recovery plates were incubated for 14 days, after which positive wells were identified and cell concentrations determined using the 50% endpoint method.

Results: Members of the OPTI-FREE products (Express, Replenish, and Puremoist [Alcon, Fort Worth, TX]) demonstrated significantly higher percentages of antimicrobial activity compared with the renu Advanced Formula (Bausch + Lomb, Rochester, NY), Biotrue (Bausch + Lomb), Acuvue RevitaLens (Johnson & Johnson, Santa Ana, CA), and Lite products (Cooper Vision, Scottsville, NY) for four of the trophozoite strains tested.

Conclusions: Many of the popular MPS biocides maintain little or no antimicrobial activity against Acanthamoeba trophozoites, and the number of biocides in an MPS does not necessarily indicate its antimicrobial activity.

FIGURE 1

OPTI-FREE products (Express, Replenish, and Puremoist Multi-Purpose Disinfecting Solutions) maintain a significantly higher percentage of Acanthamoeba antimicrobial efficacy vs. other global market products. Quantifications are represented as mean ± standard error percent reduction vs. inoculum controls. All seven products were tested against ATCC 30461 (A), ATCC 30868 (B), ATCC 50370 (C), and ATCC 50676 (D). n = 3 to 6 per group. ^aaP < .05 vs. renu Advanced Formula, ^aP < .005 vs. renu Advanced Formula, ^bP < .005 vs. Biotrue, ^cP < .005 vs. Acuvue RevitaLens, and ^dP < .005 vs. Lite.

FIGURE 1

OPTI-FREE products (Express, Replenish, and Puremoist Multi-Purpose Disinfecting Solutions) maintain a significantly higher percentage of Acanthamoeba antimicrobial efficacy vs. other global market products. Quantifications are represented as mean ± standard error percent reduction vs. inoculum controls. All seven products were tested against ATCC 30461 (A), ATCC 30868 (B), ATCC 50370 (C), and ATCC 50676 (D). n = 3 to 6 per group. ^aaP < .05 vs. renu Advanced Formula, ^aP < .005 vs. renu Advanced Formula, ^bP < .005 vs. Biotrue, ^cP < .005 vs. Acuvue RevitaLens, and ^dP < .005 vs. Lite.

FIGURE 2

Representative images of ATCC 30461 Acanthamoeba cell death after exposure to multipurpose solutions. Propidium iodide staining results in red stain indicating cell death or lysis, whereas gray color indicates living cells. Scale bar, 100 μm; ×20 magnification.

FIGURE 3

Representative images of ATCC 50370 Acanthamoeba cell death after exposure to multipurpose solutions. Propidium iodide staining results in red stain indicating cell death or lysis, whereas gray color indicates living cells. Scale bar, 100 μm; ×20 magnification.

FIGURE 4

Representative images of ATCC 50676 Acanthamoeba cell death after exposure to multipurpose solutions. Propidium iodide staining results in red stain indicating cell death or lysis, whereas gray color indicates living cells. Scale bar, 100 μm; ×20 magnification.