Identification of microbes coexisting with Legionella spp. in bathwaters

In Japan, bathwaters are a potential source of legionellosis; therefore, the bathwater in public facilities must be regularly tested for Legionella spp. Currently, Legionella spp. is detected using the culture method, which is time-consuming and has limited accuracy. Moreover, the reproductive environment of Legionella spp. in bathwater remains unclear. Here, we investigated the environment in which Legionella spp. reproduce by analyzing the bathwater microbiota and its relationship with Legionella spp. We identified the microbiota of 112 bathwater samples collected from bathing facilities by sequencing 16S and 18S rRNA genes. Differences in the microbiota were observed between samples that tested positive and negative for Legionella spp., according to 16S rRNA sequencing and culture methods. Methyloversatilis, Cupriavidus, Phenylobacterium, Vermamoeba, and Aspidisca were highly correlated with Legionella spp. Our results support the development of strategies against legionellosis and elucidate the relationships between Legionella spp. and the coexisting microbiota in various environments.

Automated summary

In Japan, bathwaters in public facilities are a potential source of legionellosis. However, the current culture method for detecting Legionella spp. is time-consuming and has limited accuracy. This study investigated the microbiota of bathwater samples and identified several microbial species, such as Methyloversatilis, Cupriavidus, Phenylobacterium, Vermamoeba, and Aspidisca, that were highly correlated with Legionella spp. These findings contribute to the development of strategies against legionellosis.