Inclusion Criteria:  Patient older than 18 years and less than 70 years of age  Chronic rhinosinusitis (> 12 weeks of evolution) meeting the definition published in the European Paper Position2012 (1) and corresponding exclusively to the following endoscopic and CT criteria:  Nasal endoscopy showing bilateral and diffuse involvement associating edema of the mucosa of the nasal cavities and meatus with the presence of mucopurulent secretions in these areas Nasosinus CT scan showing diffuse and bilateral pansinus opacities involving at least the maxillary sinuses and the anterior and posterior ethmoids Persistent intractable purulent rhinosinusitis despite at least 2 antibiotic therapies Signed informed consent of the patient Membership in a health insurance plan or beneficiary  Exclusion Criteria:  Pregnancy or breastfeeding POS of identified primary cause (identified immune deficiency, cystic fibrosis) Chronic non-purulent rhinosinusitis (nasosinusal polyposis, allergic rhinosinusitis) Localized chronic suppurative rhinosinusitis (single sinus, unilateral) Severe hepatic insufficiency Severe renal insufficiency Severe cardiac insufficiency Documented moderate pre-existing hearing loss (>30dB) or single ear (unilateral cophosis) Major cognitive impairment or lack of French language skills preventing completion of SNOT-22 and SF-36 questionnaires Allergy to lactose Long QT on ECG (>440ms for men and >450ms for women) or cardiac arrhythmia or bradycardia (<60btm) Hypokalemia or hypomagnesemia on blood ionogram Allergy to macrolides Confirmed or suspected atypical mycobacteriosis (tuberculosis) Contraindicated drug combinations with macrolides (antivitamins K or drugs containing cisapride, colchicine, ergotamine or dihydroergotamine)  Cautionary drug combinations (non-inclusion criteria)  Atorvastatin (Increased risk of concentration-dependent rhabdomyolysis-type adverse events due to decreased hepatic metabolism of the cholesterol-lowering drug. Ciclosporin (risk of increase in ciclosporin blood levels and creatinine levels) Digoxin Drugs likely to cause torsades de pointes, in particular class anti-hypertensive and class III antiarrhythmics, antipsychotics, tricyclic antidepressants, certain fluoroquinolones Simvastatin (increased risk of rhabdomyolysis-type adverse effects (concentration-dependent), due to decreased hepatic metabolism of the cholesterol-lowering agent). Patient under guardianship or curators Lactose intolerant patient Participation in other category 1 research