Abstract
Acanthamoeba castellanii is a protozoan that is found in natural and indoor environments and has been problematic in the development of intractable acanthamoeba keratitis and as a possible factor in the respiratory disease legionellosis. Acanthamoeba keratitis is mainly caused by the wearing of contaminated contact lenses, and it has been noted that disinfectant solutions have low anti-amoebic efficacy. In addition, in legionellosis, control of amoebae in biofilms in cooling towers is necessary to prevent outbreaks of Legionella spp. In this study, we investigated the amoebicidal effect of branched fatty acids and their salts, isoC12 and isoC12K, against A. castellanii. isoC12K, which was highly effective, was also evaluated for its bactericidal effect against S. aureus and E. coli. isoC12K showed an amoebicidal effect of 4 log of magnitude after 10 minutes of contact, at a concentration of 110 mM (2.5 wt%). Even at 1000 mM (20 wt%) of isoC12, complete killing could not be observed after 10 minutes of contact. (>1000 mM). In E. coli and S. aureus, 6 log reductions were observed at 2.5 wt% (105 mM) and 0.63 wt% (26.2 mM), respectively, after 10 min of contact. In amoebae, isoC12K caused plasmalemma disruption within a short period of time, suggesting that the mechanism of action is membrane action. We expect that isoC12K, which is highly effective in killing amoebae and has no characteristic pungent odor, will be used in care products and amoebicides.
