Figure 4.

Prevalence and relative abundance of methanogens among elderly subjects living in community and according to the time spent in residential care. Prevalence and relative abundance are presented for Methanobrevibacter smithii (a and b), Methanosphaera stadtmanae (c and d), ‘Free-living clade’ Methanomassiliicoccales (e and f) and the ‘Host-associated clade’ Methanomassiliicoccales (g and h). In panels (a), (c), (e) and (g), the dark blue bars represent prevalence among subjects at T0, while the clear blue bars take into account subjects positive for at least one time point. For prevalence, Community (Com), n=125; Residential care 0–2 months (mth), n=61; 2–12 months, n=47; >1 year, n=51. Statistical analysis and representation of the relative abundance of methanogens were carried out on subjects with a positive detection of methanogens. *P<0.05, **P<0.01, ***P<0.001. Day hospital category is not presented for clarity but is never different from Community.