7th joint conference "Joint Microbiology & Infection Conference 2024" of the DGHM and VAAM

Abstract: Legionella are natural inhabitants of building plumbing biofilms (e.g. shower hoses), where interactions with other microorganisms influence their survival, proliferation, and death. Their interactions with their surrounding microbiome remain poorly understood. Here, we investigated the associations of Legionella with prokaryotic and eukaryotic microbiomes in biofilm samples extracted from 85 shower hoses of a single residential building. We used specific ddPCR quantification as well as general 16S rRNA and 18S rRNA amplicon sequencing to characterize the shower hose microbiomes. Sequencing data revealed a complex prokaryotic and eukaryotic microbiome in all samples. Legionella spp. relative abundance in the biofilms ranged between 0 - 7.8%, of which only 0 - 0.46% was L. pneumophila. Our data suggests that some microbiome members were associated with high Legionella relative abundance (e.g., Chthonomonas, Vrihiamoeba), while others were associated with low Legionella relative abundance (e.g., Aquabacterium, Vannella). Interestingly, the data analysis also revealed high genetic variability in the 16S rRNA sequences assigned to the genus Legionella (30 unique Amplicon Sequence Variants detected).  The correlations of the different Legionella variants with microbiome members showed distinct patterns, suggesting separate ecological niches potentially occupied by different Legionella species. This study provides insights into the ecology of Legionella with respect to: 1) the colonization of a high number of real shower hoses biofilm samples; 2) the ecological meaning of associations between Legionella and co-occurring prokaryotic/eukaryotic organisms; 3) the presence of multiple species of Legionella in building plumbing systems, and the potential of 16S rRNA based detection of Legionella diversity in the environment.

Frederik Hammes

Invited Speaker