- Presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the subject or the quality of the data NOTE: For subjects on continuous antibiotic therapy for at least 6 months one continuous antibiotic or alternating two different antibiotics, they can maintain their current therapy. If the subject is alternating between two different inhaled antibiotics each month, Visit 1 should coincide with the "on" cycle of one of the inhaled antibiotics for consistency during the treatment period. For subjects on alternate month TOBI®, colistin or Cayston therapy, the "off" cycle must coincide with the Treatment Phase of the study. Subjects should be scheduled for Screening Visit during their one-month "on" period, and may resume taking TOBI®, colistin or Cayston after completion of Visit 6 (Day 42) or early termination.