Obstructive sleep apnea syndrome (OSAS) causes intermittent hypoxia and sleep fragmentation, which may alter gut microbiota composition. We primarily aimed to compare intestinal Desulfovibrio detection/abundance between patients with moderate-to-severe OSAS and healthy controls. Secondarily, we evaluated the association between Desulfovibrio and polysomnographic oxygen desaturation parameters, including ODI and minimum SpO2.

In this prospective cross-sectional study, 30 patients with moderate or severe OSAS and 20 healthy volunteers were included. All participants followed a balanced diet for 15 days before overnight polysomnography and fecal sampling. Fecal samples collected the morning after polysomnography were stored at −80°C and analyzed by quantitative real-time PCR. Between-group comparisons and associations with polysomnographic parameters were evaluated.

Desulfovibrio was detected in 11 of 50 participants (6 patients, 5 controls). Although bacterial concentration was numerically higher in the OSAS group, the difference was not statistically significant. No significant differences in demographic characteristics or sleep parameters were observed according to Desulfovibrio presence. Among patients with OSAS, Desulfovibrio was not significantly associated with apnea-hypopnea index or oxygen desaturation-related parameters.

This is, to our knowledge, the first human study to examine whether intestinal Desulfovibrio colonization is increased in OSAS and related to intermittent hypoxia. In this cohort, Desulfovibrio colonization did not differ significantly between OSAS and control groups and was not associated with polysomnographic desaturation indices. Larger, adequately powered studies with broader microbiome profiling are needed.