CFTR and cystic fibrosis: Evenif primary infection is characterized by a low bacterial load, thesetypes of infections easily become chronic because of reduced mucociliaryclearance (caused by CFTR alteration), superficial airway fluid hypertonicity,and resistance toward β-lactam antibiotics, mainly due to PA strains that produce serine and metal β-lactamases.22,23 It is also important to underline how chronic infection in turnprompts pulmonary tissue destruction, thus further worsening the clinicalpicture for CF patients.