The Application of Cold Atmospheric Gas Plasma CAP to Inactivate 1 Acanthamoeba and other Ocular Pathogens 2 3 4
27 Objectives: Currently there are estimated to be approximately 3.7 million contact lens wearers 28 in the UK and 39.2 million in North America. Contact lens wear is a major risk factor for 29 developing an infection of the cornea known as keratitis due to poor lens hygiene practices. 30 Whilst there is an international standard for testing disinfection methods against bacteria and 31 fungi (ISO 14729) no such guidelines exist for the protozoan Acanthamoeba which causes a 32 potentially blinding keratitis most commonly seen in contact lens wearers, and as a result many 33 commercially available disinfecting solutions show incomplete disinfection after 6 and 24 hr 34 exposure. 35 36 Methods: Challenge test assays based on international standard (ISO 14729) were used to 37 determine the antimicrobial activity of Cold Atmospheric Gas Plasma (CAP) against 38 Pseudomonas aeruginosa, Candida albicans and trophozoites and cysts of Acanthamoeba 39 polyphaga and Acanthamoeba castellanii. 40 41 Results: The complete inactivation of P. aeruginosa and C. albicans was achieved in 0.5 min 42 and 2 min respectively. Trophozoites of A. polyphaga and A. castellanii were completely 43 inactivated in 1 min and 2 min respectively. Furthermore, for the highly resistant cyst stage of 44 both species complete inactivation was achieved after 4 min exposure to CAP. 45 46 Conclusions: This study has demonstrated that the CAP technology is highly effective against 47 bacterial, fungal and protozoan pathogens. The further development of this technology has 48 enormous potential as this approach is able to deliver the complete inactivation of ocular 49 pathogens in minutes compared to commercial multipurpose disinfecting solutions which 50 require a minimum 6 hrs. 51 52 Importance 53 This study has demonstrated that the CAP technology is highly effective against bacterial, fungal and protozoan pathogens. The further development of this technology has enormous potential as this approach is able to deliver the complete inactivation of ocular pathogens in minutes compared to commercial multipurpose disinfecting solutions which require a minimum