The purpose of this study is to evaluate if the antibiotic Ampicillin is safe and tolerated in patients that have generalized dystonia caused by the DYT-1 gene mutation, as compared to patients treated with a placebo. A placebo is a pill that looks and tastes the same as the real drug, but without the active ingredient. The second objective of this study is to determine if dystonia symptoms improve while on the study drug.

This is a double-blinded and randomized drug study: neither the patient nor the investigator know if patients are taking study drug (Ampicillin) or placebo.

Three study visits will include neurological exams, review of medical history, genetic test results and video-taped BFM-DRS motor scales. Patients will receive medication during baseline visit, consisting of either Ampicillin drug or placebo, which will be consumed twice daily for 28 days. Following a washout period (no drugs) of 7 days, patient will return to clinic for second study visit and receive second set of medication (placebo -vs- Ampicillin). Medication will be consumed twice daily for 28 days, with patient returning to clinic after a washout period of 7 days for final study visit in clinic.

Inclusion Criteria:

• DYT-1 dystonia, confirmed by genetic testing
• Between ages of 7 and 80 years
• BFM-DRS score greater than 6

Exclusion Criteria:

• Negative DYT-1 dystonia gene test
• Allergy to penicillins or cephalosporins
• Concurrent bacterial, viral or fungal infection at time of enrollment
• Pregnancy
• Inability to follow study protocol
• Lactose intolerance (placebo contains lactose powder)