Enhanced killing of Acanthamoeba cysts with a plant peroxidase-hydrogen peroxide-halide antimicrobial system.
The activity of H(2)O(2) against the resistant cyst stage of the pathogenic free-living amoeba Acanthamoeba was enhanced by the addition of KI and either horseradish peroxidase or soybean peroxidase or, to a lesser degree, lactoperoxidase. This resulted in an increase in the cysticidal activity of 3% (wt/vol) H(2)O(2), and there was >3-log killing in 2 h, compared with the 6 h required for comparable results with the peroxide solution alone (P < 0.05). With 2% H(2)O(2), enhancement was observed at all time points (P < 0.05), and total killing of the cyst inoculum occurred at 4 h, compared with 6 h for the peroxide alone. The activity of sublethal 1% H(2)O(2) was enhanced to give 3-log killing after 8 h of exposure (P < 0.05). No enhancement was obtained when KCl or catalase was used as a substitute in the reaction mixtures. The H(2)O(2) was not neutralized in the enhanced system during the experiments. However, in the presence of a platinum disk used to neutralize H(2)O(2) in contact lens care systems, the enhanced 2% H(2)O(2) system gave 2.8-log killing after 6 h or total cyst killing by 8 h, and total neutralization of the H(2)O(2) occurred by 4 h. In contrast, 2% H(2)O(2) alone resulted in <0.8-log killing of cysts in the presence of the platinum disk due to rapid (<1 h) neutralization of the peroxide. Our observations could result in significant improvement in the efficacy of H(2)O(2) contact lens disinfection systems against Acanthamoeba cysts and prevention of acanthamoeba keratitis.
Hughes
Reanne
R
Department of Microbiology and Immunology, University of Leicester, Leicester LE1 9HN, United Kingdom.
Andrew
Peter W
PW
Kilvington
Simon
S
D000048:Acanthamoeba / Q000187:drug effects* / Q000254:growth & development / Q000472:pathogenicity; D015823:Acanthamoeba Keratitis / Q000517:prevention & control; D000818:Animals; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects / Q000469:parasitology; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D010544:Peroxidases / Q000494:pharmacology; D010944:Plants / Q000201:enzymology; D010984:Platinum / Q000494:pharmacology; D011193:Potassium Iodide / Q000494:pharmacology
D004202:Disinfectants; D011193:Potassium Iodide; D010984:Platinum; D006861:Hydrogen Peroxide; D010544:Peroxidases