Comparison of Hydrogen Peroxide Contact Lens Disinfection Systems and Solutions against Acanthamoeba polyphaga

Abstract

Acanthamoeba is a free-living amoeba causing a potentially blinding infection of the cornea. Contact lens wearers are most at risk and account for some 95% of cases. Hydrogen peroxide is used for contact lens disinfection due to its broad antimicrobial activity. Lenses must be neutralized before use to avoid pronounced stinging and possible corneal damage. Neutralization is achieved by adding a catalyst during the disinfection process (one-step) or afterwards (two-step). Here, the activities of commercial peroxide systems and individual solutions against trophozoites and cysts of Acanthamoeba polyphaga were compared. All disinfection systems were active against trophozoites, giving a >3-log (99.9%) kill within 1 h. Of the four one-step systems, only one showed some cysticidal activity, giving a 1.28 ؎ 0.41-log reduction. Both two-step systems were cysticidal, giving a >3-log kill at 4 h. All system peroxide solutions were cysticidal, giving a >3-log kill by 4 to 6 h. Variation in the cysticidal rate was observed with two solutions that gave a 1.8-to 2.1-log kill at 4 h compared with 3.0 to 4.0 for the rest (P < 0.05). No cysticidal activity was found with the peroxigen sodium perborate or the contact lens protein remover subtilisin A. Two-step systems are cysticidal providing contact times of at least 4 h are employed. Variation in cyst killing occurs between peroxide solutions, possibly due to formulation differences. One-step systems are less effective against Acanthamoeba cysts due to rapid peroxide neutralization. The cysticidal activity of one-step systems could be improved if neutralization rates were retarded.

One- and two-step hydrogen peroxide contact lens disinfection solutions against Acanthamoeba: How effective are they?

“…18 An incubation of 15 min is sufficient to kill most bacteria and to inactivate HIV, for Acanthamoeba an incubation of 1-3 h with 3% hydrogen peroxide is necessary. [18][19][20] However, hydrogen peroxide is toxic to the ocular epithelium. 21 In one-step systems neutralisation of the hydrogen peroxide is achieved by a catalytic platinum disk or a tablet containing catalase which is located into the contact lens storage case.…”

“…Our results showing the good cysticidal activity of the two-step system Oxysept 1 correspond to those of other studies and can be explained by the long exposure time to 3% hydrogen peroxide which is not deactivated by a catalytic system (tablet or disk). 20,23 Although the Titmus H 2 O 2 system for disinfection of soft and rigid contact lenses works with hydrogen peroxide at a concentration of only 0.6%, it is more effective than the one-step systems, that contain 3% H 2 O 2 , but in that the neutralisation process starts immediately. This shows clearly, that also with 0.6% H 2 O 2 a complete destruction of Acanthamoeba cysts can be achieved, if this concentration is held up during 8 h and not deactivated by a catalytic system.…”

Avaliação da ação antimicrobiana de soluções multiuso para desinfecção de lentes de contato hidrofílicas, in vitro

“…O "Food and Drug Administration" (FDA, Estados Unidos da América), em conjunto com o "International Standards Organization" (ISO 14729, Estados Unidos da América), têm padrões rigorosos para a aprovação da efetividade das soluções de desinfecção para LC (17)(18) . Os testes desenvolvidos pelo ISO 14729 avaliam a interação direta da solução com o microrganismo, sem intermédio das LC.…”

How Could Contact Lens Wearers Be at Risk of Acanthamoeba Infection? A Review

“…111 Old contact lenses could colonise more microorganisms due to the increased lens surface tear and wearrelated scratches 40 or to the accumulated deposits. [43][44][45] The relationship between repeated use of daily disposable lenses and risk of Acanthamoeba 112,113 and microbial keratitis 93,114 is well established.…”

“…40,41 The serine protease subtilisin A enzyme used for protein removal from contact lenses has been found to have no cysticidal action even after 24 hours of exposure. 45 However, it could lower the number of protozoa attached to lens surface through protein removal.…”