Role of fatty acid salts as anti <i>Acanthamoeba</i> agents for disinfecting contact lens

Abstract

Acanthamoeba is found in seawater, fresh water, and soil and is an opportunistic pathogen that causes a potentially blinding corneal infection known as Acanthamoeba keratitis. The antiamoeba activity of 9 fatty acid salts potassium butyrate C4K , caproate C6K , caprylate C8K , caprate C10K , laurate C12K , myristate C14K , oleate C18:1K , linoleate C18:2K , and linolenate C18:3K was tested on Acanthamoeba castellanii ATCC 30010 trophozoites and cysts . Fatty acid salts 350 mM and pH 10.5 were prepared by mixing fatty acids with the appropriate amount of KOH. C8K, C10K, and C12K showed growth reduction of 4 log-units 99.99% suppression in A. castellanii upon 180 min incubation at 175 mM, whereas the pH-adjusted control solution showed no effect. After the amoeba suspension was mixed with C10K or C12K, cell membrane destruction was observed. The minimum inhibitory concentration of C10K and C12K was also determined to be 2.7 mM. Confirmation tests were conducted using contact lenses to evaluate the effectiveness of C10K and C12K as multi-purpose solutions. Experiments using increasing concentrations showed reduced numbers of living cells in C10K 5.5 mM, 10.9 mM and in C12K 5.5 mM, 10.9 mM . These results demonstrate the inhibitory activity of C10K and C12K against A. castellanii and indicate their potential as anti-amoeba agents.

Acanthamoeba keratitis: a review of biology, pathophysiology and epidemiology

“…As noted in the scientific literature, 16,19,53,[80][81][82][83] the first report of AK was described by Nagington in 1974. 84 In the following years, AK was mainly related to ocular trauma.…”

Anti-amoeba Effect of Branched Medium Chain Fatty Acids and Their Salts on Acanthamoeba Castellanii

“…The results of this study suggest that the branched medium chain fatty acids have higher anti-amoeba effect on amoebae than their potassium salts. Previous anti-amoeba studies on A. castellanii showed a 4-log reduction in growth when treated with 175 mM potassium caprylate (C8K), potassium caprate (C10K), and potassium laurate (C12K) for 180 min [15]. In addition, cell membrane disruption was observed after mixing the amoeba suspension with C10K or C12K, and the MIC of C10K and C12K was 2.7 mM.…”

“…However, the disinfection effect of MPS is weaker than other contact lens disinfection methods, and hypersensitivity may occur, pointing to another disadvantage [12], [13]. Moreover, according to the 2009 National Consumer Center report in Japan, it was shown that anti-amoebic activity of commercially available MPS is very low [14], [15]. MPS contains polyhexanide hydrochloride as a main component [14], [16], [17], however, even after an incubation period of 8 hours, commercially available MPS decreased only 1/10 or less cells, in 4 of 8 strains [14], [15].…”

“…Moreover, according to the 2009 National Consumer Center report in Japan, it was shown that anti-amoebic activity of commercially available MPS is very low [14], [15]. MPS contains polyhexanide hydrochloride as a main component [14], [16], [17], however, even after an incubation period of 8 hours, commercially available MPS decreased only 1/10 or less cells, in 4 of 8 strains [14], [15]. In addition, MPS is mainly targeted for eliminating bacteria and fungi, and is hardly considered for preventing eye infections due to amoeba.…”

“…Previous studies on anti-amoebic activity have reported antibacterial tests using straight chain fatty acids and their salts [15], in addition to antibacterial tests against fungi [18], bacteria [19] and other microbial agents. Fatty acid salts are carboxylic acid salts of chain hydrocarbons, and are surfactants formed from fatty acids and alkalis with both hydrophilic and hydrophobic properties.…”