Rifaximin in Patients With Monoclonal Gammopathy

Inclusion Criteria: * Clinical diagnosis of monoclonal gammopathy of undetermined significance based on International Myeloma Working Group (IMWG) criteria * Patients will be enrolled into one of 3 cohorts: * Cohort A: IgA gammopathy * Cohort B: IgG gammopathy / or light chain gammopathy * Cohort C: IgM gammopathy / asymptomatic macroglobulinemia * Ability to understand and the willingness to sign a written informed consent document Exclusion Criteria: * Patients who have received antibiotics within last 3 weeks * Patients who are receiving any other investigational agents for gammopathy. Patients with clinical myeloma requiring anti-myeloma therapy are also excluded * History of allergic reactions or intolerance attributed to rifaximin or compounds of similar chemical or biologic composition to antibiotic under study * The effects of rifaximin on the developing human fetus are unknown. For this reason, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 4 months after completion of rifaximin administration