Chronic lung infections, including in patients with cystic fibrosis, are often difficult to treat with antibiotics. Antibiotics that are effective in conventional antibiotic susceptibility assays do often not lead to clinical improvement in this patient population. Preliminary research from our laboratory indicates that lung micro-environmental factors (such as lung epithelial cells) influence the activity of antibiotics. This project aims at studying the influence of the patient-specific lung micro-environment on antibiotic efficacy.