Invesitgation of fecal pH in Healthy Volunteers Receiving Oral Omadacycline or Vancomycin

Antibiotics have profound disrupting effects on the gut microbiome including pH. An easy method to measure gut dysbiosis is not currently available. This study aims to investigate the fecal pH in healthy volunteers receiving antibiotics and to assess the utility of fecal pH as a potential gut dysbiosis marker. Antibiotics have profound disrupting effects on the gut microbiome including pH. An easy method to measure gut dysbiosis is not currently available. The aim of this study was to investigate the fecal pH in healthy volunteers receiving antibiotics and to assess the utility of fecal pH as a potential gut dysbiosis marker. Healthy subjects aged 18 and 40 years were recruited and randomized to receive either oral omadacycline or vancomycin for 10 days. Fecal samples were collected at baseline, during therapy, and follow-ups. Approximately 100 mg of solid fecal sample was treated with 50 uL of NaCl for the pH measurement. A major shift from the baseline pH was observed on day 9 in the vancomycin group (7.12 ± 0.74; mean ± SD) while on day 5 in the omadacycline group (6.86 ± 0.8; mean ± SD). Both antibiotic groups had an increasing trend during therapy and a decreasing trend by the follow up days. The findings of our study suggest that both omadacycline and vancomycin modify the pH of the gastrointestinal tract of otherwise healthy adults to be more alkaline. Future studies are needed to better understand the implications of this phenomenon.