A randomized, double-blind, placebo-controlled clinical trial of azithromycin in Campylobacter concisus culture positive patients with diarrhea. The clinical characteristics of emerging Campylobacter concisus in adults is vomiting and persistent diarrhea. Whether patients may benefit from antibiotic treatment is unknown. The purpose of this trial is to investigate whether antibiotic treatment with azithromycin of Campylobacter concisus induced diarrhea can better the symptoms and shorten the duration of illness.

Inclusion Criteria:

• Patients with culture-positive stool sample with Campylobacter concisus
• Diarrheic patients ≥ 18 years
• symptoms of diarrhea defined as three or more watery stools per day or
• two watery stools per day + at least one of the following symptoms: abdominal pain, nausea, vomiting or fever.
• Diarrheic symptoms for a minimum of 24 hours before enrollment.
• Diarrheic symptoms for a maximum of 21 days before enrollment.
• Informed oral and signed written consent, with documentation that all relevant information about the study is given to the patient.
• The patient must be willing and able to participate in the trial.

Exclusion Criteria:

• Hypersensitivity to azithromycin, erythromycin, macrolide or other ketolide-antibiotics
• Pregnancy or breastfeeding (if relevant).
• Culture positive stool sample with a Co-pathogen.
• Treatment with other antibiotics (in any stage 21 days before the first stool sample).
• Patients with severe liver disease.
• Patients with severe renal impairment (GFR <10 ml / min).
• Patients with congenital or documented acquired QT prolongation.
• Patients treated with other active drugs that prolong the QT interval such as: antiarrhythmics of classes IA and III, cisapride and terfenadine.
• Patients with electrolyte disorders, particularly hypokalemia and hypomagnesemia.
• Patients with clinically relevant bradycardia, arrhythmia or severe heart failure.
• Inflammatory bowel diseases
• Chronic diarrhea of known cause.
• Dementia.
• Serious illness less than 21 days from the planned entry into the study.
• Patients treated with medications that have interactions with azithromycin e.g. alkaloids, ciclosporin or amiodarone.
• Patients involved in the planning or execution of the study.