STaph Aureus Resistance-Treat Early and Repeat (STAR-TER)

To evaluate the micro-biologic efficacy and safety of a streamlined treatment for early onset methicillin-resistant staphylococcus aureus (MRSA) in patients with cystic fibrosis.

Inclusion Criteria: 1. Male or female ≥ 2 and ≤ 45 years of age at the Screening Visit. 2. Documentation of a CF diagnosis as evidenced by one or more clinical features consistent with the CF phenotype and one or more of the following criteria: 1. sweat chloride ≥ 60 milliequivalents/liter by quantitative pilocarpine iontophoresis test (QPIT) 2. two well-characterized mutations in the cystic fibrosis transmembrane conductive regulator (CFTR) gene 3. abnormal nasal potential difference(NPD) (change in NPD in response to a low chloride solution and isoproteronol of less than -5 mV) 3. First OR early MRSA colonization defined as: 1. First MRSA colonization: first documented isolation of MRSA from respiratory tract occurred ≤ 6 months prior to screening 2. Early MRSA colonization: MRSA was previously isolated from the respiratory tract ≤ 2 times over the past 3.5 years, but this was followed by at least 1 year of documented negative cultures for MRSA 4. MRSA is available to the central laboratory - either the incident MRSA isolate from the clinic visit or the subject is MRSA positive at the screening visit 5. Clinically stable with no significant changes in health status within the 14 days prior to screening 6. Written informed consent (and assent when applicable) obtained from subject or subject's legal representative and ability for subject to comply with the requirements of the study Exclusion Criteria: 1. Received antibiotics with activity against MRSA within 28 days prior to screening 2. Use of an investigational agent within 28 days prior to screening 3. For subjects ≥ 6 years of age: FEV1 at screening \< 25% of predicted for age based on the Wang (males \< 18 years, females \< 16 years) or Hankinson (males ≥ 18 years, females ≥ 16 years) standardized equations 4. MRSA from the screening culture or the most recent clinical care visit within 6 months prior to screening resistant to TMP/SMX 5. History of intolerance to topical chlorhexidine or mupirocin 6. History of intolerance to both TMP/SMX and minocycline 7. \< 8 years of age and allergic or intolerant to TMP/SMX 8. ≥ 8 years of age and allergic or intolerant to TMP/SMX and MRSA isolate (from screening or clinical care visit)is resistant to minocycline 9. For females of child bearing potential: pregnant, breastfeeding, or unwilling to use barrier contraception through Day 42 of the study 10. Subjects with history of abnormal renal function will need screening labs showing normal function Abnormal renal function is defined as estimated creatinine clearance \