MODEL RELEASED. Antibiotic therapy for respiratory infection in cystic fibrosis (CF). Nurse preparing an intravenous infusion of the cephalosporin antibiotic Ceftazidime, delivered via a cannula in a vein in the girl's arm. Cystic fibrosis is an inherited disorder that results in an overproduction of thick mucus, which obstructs the bronchi, intestinal glands & pancreas. Severe respiratory infections are a common complication. Advances in molecular genetics have resulted in the identification of the CF gene, which is used as the basis for diagnostic tests & subsequent counselling of CF gene carriers.