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.
Department of Microbiology and Immunology, University of Leicester, Leicester LE1 9HN, United Kingdom.
Reanne
R
Hughes
Peter W
PW
Andrew
Simon
S
Kilvington
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