Oral, gut and skin microbiota characterization in patients with heart valve disease with or without infective endocarditis: a pilot study

Purpose: Few studies have explored the relationship between host microbiota and infective endocarditis (IE). We compared oral, gut, and skin microbiota in patients awaiting heart valve replacement with or without IE, and correlated findings with clinical data, including causative pathogens and prior antibiotics use.Patients and Methods. In this prospective pilot study, 36 patients were enrolled (25 IE cases, 11 controls). Oral, faecal, and skin samples were collected before surgery and analysed by 16S rRNA sequencing.Results. Cases and controls were similar except for higher inflammatory markers and prevalence of prosthetic valves in cases. Causative IE pathogens were Staphylococcus spp., Streptococcus spp. and Enterococcus spp. Dysbiotic features were observed in oral, gut, and skin microbiota of cases, with reduced diversity in oral and skin communities and overall community depletion compared to controls. A few taxa were enriched, including Oxalobacteraceae (oral) and Bacteroides (gut). Concordance between bacterial changes and blood isolates was low, suggesting dysbiosis may be potentially associated with IE risk rather than acting as a direct reservoir of specific pathogens.Conclusions. Dysbiosis may represent a relevant but underexplored factor linked to IE. Further studies are needed to clarify the underlying pathogenetic mechanisms.