Tobramycin Delivered by Nebulized Sonic Aerosol for Chronic Rhinosinusitis Treatment of Cystic Fibrosis Patients

Cystic fibrosis (CF) is the most common lethal autosomal recessive disorder in the Caucasian population affecting ~1:3000 children, with a carrier frequency of 1:25. It is a multisystem disorder where pulmonary and sinonasal involvements occur in 90-100% of patients, and up to 86% of children have nasal polyps . Patients with CF develop chronic rhinosinusitis (CRS) due to the defect in the cystic fibrosis Transmembrane Regulator (CFTR) protein. The membrane lining the paranasal sinuses and the nose is identical to the membrane lining the lungs. As in lower airways (LAW) the defect CFTR protein result in viscous mucus . Consequently mucociliary function is reduced, which facilitates bacterial colonization and eventually infection leading to rhinosinusitis . In the past decades infection of the lower airways was the most prominent focus in treatment protocols for CF. Over the years infection of the upper airways (UAW) gradually gained more attention in CF.

Previous research in the microbiology of the upper airways (UAW) in CF displayed that Haemophilus influenzae, Pseudomonas aeruginosa and Staphylococcus aureus were most frequently cultures from the UAW . Since several studies showed concordance between organisms in the UAW and the LAW in CF, the hypothesis evolved that the UAW might influence the patient pulmonary status . Moreover, comparison of UAW and and LAW cultures in CF adult patients showed that Pseudomonas aeruginosa can be cultured from the UAW after eradication therapy which may suggest persistence of Pseudomonas aeruginosa in the UAW . This problem is highlighted in double lung transplant where UAW also appears as a protective niche of adapted clones of bacteria, which can intermittently spread this pathogen to the lung.

CRS treatment in CF patients is based on daily nasal lavages but above all on local or systemic antibiotic treatments to eradicate bacteria in sinuses . Local therapy is favoured in CRS treatment of CF patients to avoid antibiotic side effects, changing organisms or resistance patterns. Sonic aerosol therapy with antibiotics for 15 days is commonly used for CRS in non CF patients to improve sinonasal symptoms and reduce purulent secretions as sound addition in pneumatic aerosol in head corpse's models creates an acoustic pressure at the ostia to improve the aerosol penetration in maxillary sinuses . However its efficacy on bacterial carrying in sinuses is not proved . At the opposite, efficacy of aerosol of tobramycin to LAW was proved in CF patients with a decrease of the density of Pseudomonas aeruginosa, an improvement of FEV, and fewer pulmonary exacerbations .

At the present time, efficacy of antibiotic (tobramycin) delivered by nebulized sonic aerosol for CRS treatment of CF patients is unknown particularly on bacterial carrying.

The aim of this study is to demonstrate that nebulized sonic aerosol therapy with tobramycin in Cystic Fibrosis patients decreases significantly bacterial carrying in sinuses, sinus ostia of middle meatus and sputum compared to nebulized sonic aerosol therapy with placebo and that nebulized sonic aerosol therapy improves sino-nasal symptoms and endoscopic scores, quality of life and lung function.