Efficacy of Rifaximin in Preventing Campylobacteriosis

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.)