This clinical trial is focused on studying the effects of a probiotic treatment on the gut health of patients who are receiving antibiotic therapy for a condition known as erythema migrans, which is an early skin form of Lyme disease. The treatment being tested is called Saccharomyces boulardii CNCM I-745, a type of beneficial yeast that is often used to support gut health. The study will also involve the use of an antibiotic called amoxicillin, which is commonly prescribed to treat bacterial infections, including those associated with Lyme disease. Additionally, some participants will receive a placebo, which looks like the treatment but contains no active ingredients.

The purpose of the study is to understand how Saccharomyces boulardii CNCM I-745, either alone or in combination with amoxicillin, affects the gut microbiota, which is the community of microorganisms living in the intestines. Participants in the study will take the treatments orally in the form of capsules. The study will last for a period of up to 21 days, during which time participants will be monitored for changes in their gut health and any side effects they may experience.

Throughout the study, participants will be asked to keep a diary of their bowel movements and any symptoms they experience. This information will help researchers assess the impact of the treatments on gut health and the occurrence of antibiotic-associated diarrhea. The study aims to provide valuable insights into how probiotics like Saccharomyces boulardii CNCM I-745 can support gut health during antibiotic treatment for conditions such as erythema migrans.