Effect of Saccharomyces Boulardii CNCM I-745 on Gut Microbiota in Patients Undergoing Antibiotic Therapy (in the Context of Erythema Migrans (Early Skin Form of Lyme Borreliosis))

At inclusion visit (V1), the Investigator will dispense and ask the subject to take Amoxicillin 1000 mg bid for 14 days + Saccharomyces boulardii 250 mg x 2 twice a day for 21 days

At inclusion visit (V1),the Investigator will dispense and ask the subject to take Amoxicillin 1000 mg bid for 14 days + a matching placebo bid for 21 days

"The subject will be asked to collect thanks to four OMNIgene® •GUT OMR-200 kits :~* an initial stool collection when returning home at D1 (in any case before any intake of amoxicillin and of the investigational medication and up to 1 day after D1).~* a stool collection at home after the phone call 1, Day 7 (stool collection up to Day 7 + 1 day)~* a stool collection at home after the phone call 2, Day 14 (stool collection up to Day 14 + 1 day)~* at home the day of the Visit 2, Day 21 (stool collection up to Day 21 + 1 day)"

All included subjects will have to complete a stool diary BSFS (Bristol Stool Form Scale) daily and at each bowel movement, from Day 1 until the end of study treatment (Day 21). The patient will fill the form with the date, the time, and the stool texture.

All included subjects will have to complete a GSRS (Gastrointestinal Symptom Response Score) questionnaire weekly from Day 1 until the end of the study treatment (Day 21).