- Participants with any acute systemic administration of an antibiotic for any reason in the previous 4 weeks; however, a low stable dose of an antibiotic (such as azithromycin 250 or 500 milligram [mg] up to 3 times per week) is allowed. Moreover, chronic treatment (that is, daily for at least 1 month) with an inhalatory antibiotic (for example, colistin, tobramycin, or ceftazidime) is allowed