Effects of fragrance ingredients on the uptake of Legionella pneumophila into Acanthamoeba castellanii

Abstract

Acanthamoeba castellanii, a ubiquitous organism in water environments, is pathogenic toward humans and also is a host for bacteria of the genus Legionella, a causative agent of legionellosis. Fragrance ingredients were investigated for their antibacterial activity against planktonic Legionella pneumophila, amoebicidal activity against A castellanii, and inhibitory effect against L. pneumophila uptake into A castellanii. Helional® exhibited relatively high antibacterial activity [minimum inhibitory concentration (MIC), 32.0 μg/mL]. Anis aldehyde, canthoxal, helional® and vanillin exhibited amoebicidal activity (IC 50 values, 58.4±2.0, 71.2± 14.7, 66.8±8.3 and 49.1±2.5 μg/mL, respectively). L. pneumophila pretreatment with sub-MICs (0.25×MIC) of anis aldehyde, canthoxal, cortex aldehyde® 50 percent or vanillin evidently reduced L. pneumophila uptake into A castellanii (p < 0.01). Thus, fragrance ingredients were good candidates for disinfectant against L. pneumophila and A castellanii.