Microbiota of Bronchial Tree in Children with Bronchial Asthma: today and 20 years ago

Abstract

Study Objective: To analyze the microbiota of the lower respiratory tract in children with bronchial asthma, depending on the severity, period of the disease and inflammatory phenotype, as well as to compare the obtained data on the microbiota with the data obtained two decades ago. Study Design: The study is organized in a cross-sectional manner. Materials and Methods. The study involved 66 children with bronchial asthma aged 6 to 18 years old. All participants had their microbiota of the bronchial tree studied by bacteriological examination of induced sputum samples; in some children, the cytology of induced sputum was analyzed (n = 36). Statistical analysis was performed using Statistica 10.0. Intergroup differences in qualitative parameters were evaluated using χ2 and Fisher’s exact test. Statistically significant changes were are p < 0.05. Study Results. The predominant flora of the lower respiratory tract in children with bronchial asthma was Streptococcus spp. (66.7%), Staphylococcus spp. (33.3%) and Neisseria spp. (30.3%). There were no significant differences in the spectrum of the microflora of the bronchial tree depending on the period (exacerbation/remission) and the severity of the disease. When analysing the spectrum of the microbiota depending on the inflammatory phenotype, it was found that all sputum samples from patients with neutrophilic inflammatory phenotype were inoculated with Streptococcus spp., and in 25% of cases it was Streptococcus pneumonia. In patients with an eosinophilic inflammatory phenotype, most common was Staphylococcus spp. (75.0%), in particular Staphylococcus aureus (62.5%). When analysing the spectrum of microflora in a temporal aspect, it turned out that 20 years ago 41.2% of sputum samples did no demonstrate microflora growth. The growth of Streptococcus spp. and, in particular, Streptococcus pneumoniae, was significantly less frequent, Staphylococcus spp. were shown with the same frequency as now. Conclusion. The relationship between bronchial asthma and airway microbiota is complex and controversial. The revealed patterns show that the severity of bronchial asthma and the period of the disease do not affect the spectrum of microflora; however, statistically significant differences were found depending on the inflammatory phenotype. Since asthma phenotypes are immunological and physical-chemical characteristics of the mucous membrane of lower respiratory tract, this may be the reason for their selective impact of the microbial growth in respiratory tract, and on their biogeography, thus impacting the course and management of bronchial asthma. Keywords: bronchial asthma, respiratory tract microbiota, inflammatory phenotype, children.