Early Methicillin-resistant Staphylococcus Aureus (MRSA) Therapy in Cystic Fibrosis (CF)

Inclusion Criteria:

1. Male or female ≥ 4 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:

- sweat chloride ≥ 60 mEq/liter by quantitative pilocarpine iontophoresis test
(QPIT)

- two well-characterized mutations in the cystic fibrosis transmembrane conductive
regulator (CFTR) gene

- Abnormal nasal potential difference (change in NPD in response to a low chloride
solution and isoproteronol of less than -5 mV)

3. First OR early repeat MRSA colonization defined as:

- First MRSA colonization: first documented isolation of MRSA from respiratory
tract occurred ≤ 6 months prior to screening

- OR Early repeat MRSA colonization:

MRSA was previously isolated from the respiratory tract (≤ 2 times), but this was
followed by at least 1 year of documented negative cultures for MRSA as noted below:

-- At least 2 cultures performed at least 3 months apart to document 1 year of
culture negativity. Each of these cultures should be documented to have been
collected at least 1 week after end of any antibiotic prescription with MRSA
activity.

Patient again recently positive for MRSA from the respiratory tract (within 6 months
prior to screening)

4. Clinically stable with no significant changes in health status within the 14 days
prior to screening

5. 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

A repeat culture from the respiratory tract is obtained at screening but does not have to
be positive to be able to enter the study.

Exclusion Criteria:

1. Received antibiotics with activity against MRSA within 28 days prior to screening
(see study manual for list of antibiotics)

2. Use of an investigational agent within 28 days prior to screening

3. For subjects ≥ 6 years of age: FEV1 at screening < 30% 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 resistant to rifampin OR resistant to both TMP/SMX
and minocycline

5. History of intolerance to oral rifampin, or topical chlorhexidine or mupirocin

6. History of intolerance to both TMP/SMX and minocycline

7. < 8 years of age and either allergic or intolerant to TMP/SMX or screening MRSA
resistant to TMP/SMX

8. ≥ 8 years of age and allergic or intolerant to TMP/SMX and screening MRSA resistant
to minocycline

9. ≥ 8 years of age and allergic or intolerant to minocycline and screening MRSA
resistant to TMP/SMX

10. For females of child bearing potential: pregnant, breastfeeding, or unwilling to use
barrier contraception through Day 15 of the study

11. Abnormal renal function at Screening, defined as estimated creatinine clearance <50
mL/min using the Cockcroft-Gault equation

12. Abnormal liver function at the time of screening, defined as ≥2x upper limit of
normal (ULN), of serum aspartate transaminase (AST) or serum alanine transaminase
(ALT)

13. History of solid organ or hematological transplantation

14. Presence of a condition or abnormality that in the opinion of the Investigator would
compromise the safety of the patient or the quality of the data.