Chronic rhinosinusitis (CRS) is one of the most common chronic diseases, affecting the quality of life of patients who suffer. Despite medical and surgical treatments available, there are a significant number of people suffering from CRS refractory to these standard treatments.

A preliminary clinical trial conducted at CHUM Hôtel-Dieu, has allowed us to evaluate the therapeutic potential of intranasal irrigation of probiotics in patients with CRS. This treatment administered twice daily for 14 days was well tolerated and resulted in improved chronic rhinosinusitis symptoms.

Prior to deployment on a larger scale, the safety of this therapy must be confirmed in a healthy population, free of sinus disease. Therefore, this study aims to assess the safety of the use of probiotic intranasal irrigation in healthy volunteers.

If the participant (healthy volunteer) agrees to participate in the study, and after signing the information consent form, her/his participation in this project will consist to receive the experimental treatment of probiotics, to come to four (4) medical assessment visits at CHUM, over a period of time of four (4) weeks, and answer to one (1) phone call.

This study will include five (5) periods :

1. Determination of eligibility period (Day 0)
2. Saline irrigation period (Day 0 to Day 7)
3. Elimination of saline period (Day 8 to Day 14)
4. Probiotic treatment period (Day 15 to Day 21)
5. Telephone follow-up period (Day 22 to Day 28)

Inclusion Criteria:

• Men and women aged 18 and older.
• Participant in general good health.
• Absence of nasal and ear signs or symptoms.

Exclusion Criteria:

• Participant suffering from acute rhinosinusitis, chronic rhinosinusitis, symptomatic allergic rhinitis, or other sinus disease.
• Participant with diseases of the middle ear causing impairment of the eardrum or middle ear, or have had surgery of the middle ear previously, except myringotomy with insertion tube.
• Primary or acquired immunodeficiencies documented.
• Antibiotic intake within 30 days before enrollment.
• Unable to do nasal rinse.
• Pregnant woman.
• Smell score from UPSIT-40 under normal smell threshold (<34).