Microbial Biomarkers of EArly Pseudomonas Aeruginosa Colonization in CHildren With Cystic Fibrosis

This is a multicentric study in 3 phases:

• Pre-inclusion: at the first visit to the CRCM (support for a positive screening confirmed by sweat test and genotyping CFTR)
• Inclusion: possible between the 2nd visit to the CRCM (about 2 months old) and the 6th month
• Follow-up: up to 36 months old. The pace of visits will be based on the usual follow-up rate of CF infants

The clinical data as well as samples (expectorations, stools) will be collected on a monthly basis up to 6 months old and then every 2 months until one year old and finally quarterly until 3 years old.

• Tracheo-bronchial secretions will be collected at the CRCM
• Stools samples will be carried out by the parents prior to consultation with the CRCM
• A blood collection will be carried out annually in an annual report.

Inclusion criteria

• Infants aged 6 months maximum at inclusion with a confirmed diagnosis of cystic fibrosis in its classical form (positive sweat test and/or two mutations of the CFTR gene from class I to III) -Children free from any antecedent of colonization to P. aeruginosa at the time of inclusion (certified by the microbiological history supplemented by a molecular test by qPCR according to the diagram of Le gal et al., 2013)---
• Affiliation to the social security system
• Consent signed by the holders of parental authority or the sole parent holding parental authority / and "oral" agreement of the second holder

Exclusion criteria

• Severe acute illness (other than cystic fibrosis) ongoing, or requiring surgery
• Children unable to undergo the tests required by the protocol
• Children whose parent(s) is/are minors
• Children whose legal guardians do not have sufficient command of the French language
• Children under exclusive parenteral nutrition
• Refusal to participate in the study