Microbiota of the respiratory tract in children with cystic fibrosis in various subjects of the North Caucasus Federal District

Introduction. The microbial biodiversity of the respiratory tract in children with cystic fibrosis (CF) in various subjects of the North Caucasus Federal District (NCFD) has not yet been sufficiently described. In the NCFD children with CF were previously shown to have specific clinical manifestations of the disease and changes in the frequencies of pathogenic variants of the CFTR gene. In this regard, the topic of the work is relevant. The aim of the study. To detect changes in the microbiota composition of the respiratory tract in CF children in various subjects of the NCFD. Materials and methods. There were examined one hundred 48 CF children, who underwent a study of the microbiota of the respiratory tract. The patients were divided into 2 groups: by subject (children of the Chechen, Karachay-Cherkess, Ingush, Kabardino-Balkarian, North Ossetia — Alania and Dagestan Republics) and by age (1 — infants under 12 months, 2 — 1–3 years, 3 — 3–7 years, 4 — 7–17 years). Results. For the first time, changes in the quantitative and qualitative composition of the respiratory tract microbiota in CF children in various subjects of the NCFD are presented. The quantitative composition of the microbiota of the respiratory tract of CF patients is represented by 45 species of bacteria and mold from the department of ascomycetes. Gram-negative microorganisms (86.3%) occupied a significant place in the composition of the microbiota of the respiratory tract in CF patients. The proportion of Gram-positive bacteria was 13.6%. The leading microbiota in the respiratory tract in CF patients in various subjects of the NCFD were: P. aeruginosa (68.9%), S. aureus (66.8%), of which 37.1% are MRSA, H. influenzae (51.3%), Moraxella catarrhalis and K. pneumoniae (30.4%), respectively. The biodiversity of the microbiota of the respiratory tract in CF children in various subjects of the NCFD differs from other regions of the Russian Federation in the high content of P. aeruginosa and H. influenzae, they are not characterized by the isolation of Achromobacter xylosoxidans. For the first time, a unique frequency distribution of the CFTR gene alleles was revealed in children with CF in various subjects of the NCFD. The most common pathogenic variants of the CFTR gene among all subjects of the NCFD were p.Y515 (150 alleles/51.9%), p.W1282 (48 alleles/16.6%), and p.E92K (26 alleles/8.9%). While the share of these pathogenic variants in the Russian Federation was 2.48%, 1.73%, and 3.67%, respectively. Conclusion. The established patterns of biodiversity of the microbiota of the respiratory tract in CF children are necessary to optimize their treatment and prevent exacerbations of the disease. Given the high content of hemophilic bacillus in the microbiota in CF children, special attention should be paid to vaccination of children against hemophilic infection type B