This study is a randomized, double-blinded, placebo-controlled, in-patient trial evaluating the prophylactic efficacy of rifaximin against campylobacteriosis following challenge with C. jejuni.

30 healthy volunteers (2 of these were planned alternates) gave informed consent and were enrolled to participate in a study to determine the efficacy of prophylactic rifaximin in preventing diarrheal illness following challenge with C. jejuni, strain CG8421. Volunteers were screened for inclusion and exclusion criteria and were admitted to the inpatient unit of the Center for Immunization Research at Johns Hopkins University. Volunteers were treated with rifaximin or placebo in a double blind manner for four days, beginning the day prior to challenge. On the day of challenge, the volunteers were given 5x10(5) C. jejuni with bicarbonate buffer and were then monitored and treated for any symptoms. Stools were cultured daily for the excretion of C. jejuni and all subjects were treated with antibiotics to insure that the challenge strain has cleared prior to to discharge. Subjects were followed for six months following the inpatient phase to detect adverse events following the study.

Inclusion Criteria:

1. Male or female between 18 and 50 years of age, inclusive

2. General good health, without significant medical illness, abnormal physical examination findings or clinically significant laboratory abnormalities, as determined by the PI (may consult with the Research Monitor on a case-by-case basis)

3. Demonstrate comprehension of the protocol procedures and knowledge of Campylobacter illness by passing a written examination (pass grade ≥ 70%)

4. Willing to participate after informed consent obtained

5. Available for all planned follow-up visits and remain available for clinic visits (for examination, blood draws and stool collection) and monitoring for 90 days post-challenge and by phone for 180 days post-challenge

6. If the subject is female, she is eligible to enter if she is of:

   • Non-childbearing potential (i.e., physiologically incapable of becoming pregnant, including any female who is post-menopausal. For purposes of this study, postmenopausal is defined as one year without menses); or must have documentation of having undergone tubal ligation or hysterectomy. OR
   • Childbearing potential; has a negative serum pregnancy test at screening and a negative urine pregnancy test on admission (Study Day -1), and agrees to the use of an efficacious hormonal or barrier method of birth control during the study, abstinence is acceptable

Exclusion Criteria:

General health/issues

1. Presence of a significant medical condition (e.g., psychiatric conditions; gastrointestinal disease, such as peptic ulcer,symptoms or evidence of active gastritis/dyspepsia, inflammatory bowel disease, irritable bowel syndrome (as defined by the Rome III criteria or medical diagnosis); alcohol or illicit drug abuse/dependency) or laboratory abnormalities which in the opinion of the investigator preclude participation in the study
2. Evidence of Immunoglobulin A deficiency (serum IgA < 7 mg/dL or below the limit of detection of assay)
3. Positive serology results for HIV, HBsAg, or Hepatitis C virus antibodies
4. Positive urine toxicology screen
5. Significant abnormalities in screening laboratory hematology or serum chemistry, as determined by PI or PI in consultation with the Research Monitor and sponsor
6. Use of any medication known to affect the immune function (e.g., corticosteroids and others) within 30 days preceding receipt of the challenge inoculum or planned to be used during the active study period
7. Nursing mother on the day of admittance to the inpatient unit

Study-specific exclusionary conditions based on potential increased risk or complicating outcome ascertainment. (See protocol details for complete list of exclusions.)

84 days