RESPIRATORY MICROBIOTA DYSBIOSIS AND ANTIMICROBIAL RESISTANCE IN PEDIATRIC BRONCHIAL ASTHMA: A CLINICAL STUDY

ABSTRACT

The aim of this study was to investigate the composition of the nasopharyngeal microbiota and antimicrobial resistance patterns in children with bronchial asthma in the presence and absence of coinfection. The clinical study included 60 children aged 5–18 years, divided into three groups: children with bronchial asthma and coinfection, children with bronchial asthma without coinfection, and healthy controls. Microbiological examination of nasopharyngeal swabs was performed with identification of microorganisms and assessment of their antimicrobial susceptibility using the disk diffusion method. The results showed that children with bronchial asthma and coinfection were characterized by a predominance of clinically significant pathogenic microorganisms (Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Candida spp.) and a higher level of antimicrobial resistance, mainly to β-lactam antibiotics. The findings highlight the clinical significance of respiratory microbiota dysbiosis and the need for microbiological monitoring in the management of pediatric bronchial asthma.

АННОТАЦИЯ

Целью исследования явилось изучение особенностей состава носоглоточной микробиоты и характера антимикробной резистентности у детей с бронхиальной астмой при наличии и отсутствии коинфекции. В клиническое исследование были включены 60 детей в возрасте от 5 до 18 лет, разделённые на три группы: дети с бронхиальной астмой и коинфекцией, дети с бронхиальной астмой без коинфекции и группа здорового контроля. Проведено микробиологическое исследование мазков из носоглотки с определением видового состава микроорганизмов и их чувствительности к антибактериальным препаратам методом дисковой диффузии. Установлено, что у детей с бронхиальной астмой и коинфекцией преобладают клинически значимые патогенные микроорганизмы (Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Candida spp.) и отмечается более высокий уровень антимикробной резистентности, преимущественно к β-лактамным антибиотикам. Полученные результаты подчёркивают клиническую значимость дисбиоза респираторной микробиоты и необходимость микробиологического мониторинга при ведении детей с бронхиальной астмой.

Keywords: bronchial asthma; pediatric patients; respiratory microbiota; nasopharyngeal dysbiosis; coinfection; antimicrobial resistance; antibiotic susceptibility.

Ключевые слова: бронхиальная астма; детский возраст; респираторная микробиота; дисбиоз носоглотки; коинфекция; антимикробная резистентность; антибиотикочувствительность.

Introduction.  Bronchial asthma (BA) is one of the most prevalent chronic respiratory diseases among children, with a steadily increasing global incidence. According to the World Health Organization, more than 300 million people worldwide suffer from asthma, a substantial proportion of whom are children. Pediatric asthma represents a significant public health burden due to its early onset, recurrent exacerbations, long-term therapeutic requirements, and negative impact on physical development and quality of life [1].

In recent years, scientific understanding of asthma pathogenesis has expanded beyond the traditional concept of a purely immuno-allergic disorder. Growing evidence suggests that alterations in the respiratory tract microbiota play a critical role in the initiation, progression, and severity of asthma [1,2].

Coinfection represents an additional aggravating factor in children with bronchial asthma. The simultaneous presence of viral and/or bacterial pathogens is associated with more frequent exacerbations, increased symptom severity, and reduced effectiveness of standard therapeutic interventions. Numerous studies have demonstrated that pathogens such as Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus adversely influence the clinical course of asthma. Furthermore, fungal coinfection, particularly involving Candida species, may intensify immune dysregulation and further worsen clinical outcomes in asthmatic children by amplifying inflammatory responses and altering host–microbe interactions [3,4].

Antimicrobial resistance constitutes one of the most urgent challenges in modern pediatrics. Inappropriate or uncontrolled use of antibiotics contributes to the emergence of resistant microorganisms, thereby reducing the effectiveness of conventional antimicrobial therapies. In children with chronic conditions such as bronchial asthma, this problem is especially concerning, as recurrent infections often necessitate repeated antibiotic exposure [5,6].

Therefore, investigating changes in the nasopharyngeal microbiota and patterns of antimicrobial susceptibility in children with bronchial asthma, particularly in the presence of coinfections, is of considerable theoretical and practical importance. Such research provides a scientific basis for rational antibiotic selection, implementation of microbiological monitoring, and optimization of individualized therapeutic strategies. Ultimately, this approach may contribute to improved disease control, reduced exacerbation frequency, and better long-term outcomes in pediatric asthma patients.

Aim of the Study. The aim of this study is to investigate changes in the nasopharyngeal microbiota in children with bronchial asthma, both in the presence and absence of coinfections, and to assess the antimicrobial resistance characteristics of the identified microorganisms.

Materials and Methods. The study was conducted at the Pulmonology and Allergology Department of the Navoi Regional Multidisciplinary Children’s Medical Center. A total of 60 children aged 5 to 18 years were enrolled and divided into three groups. Group 1 (n = 20) consisted of children with bronchial asthma and concomitant coinfection; Group 2 (n = 20) included children with bronchial asthma without coinfection; Group 3 (n = 20) comprised healthy children who served as the control group. Nasopharyngeal swab samples were collected from all participants and subjected to microbiological examination to identify the composition of the respiratory microbiota. Antimicrobial susceptibility of the isolated microorganisms was assessed using the disk diffusion method.Statistical analysis was performed using the chi-square (χ²) test, Student’s t-test, and analysis of variance (ANOVA). Differences were considered statistically significant at a p-value of less than 0.05 (p < 0.05).

Results. In Group 1 (children with bronchial asthma and coinfection), potentially pathogenic microorganisms were detected with relatively high frequency. Streptococcus pneumoniae was isolated in approximately 12 out of 20 children, while Haemophilus influenzae was identified in about 8 cases. Fungal microorganisms were also observed, with Candida species detected in roughly 6 children. In addition, Staphylococcus aureus was isolated in about 5 participants in this group. Overall, Group 1 was characterized by a heterogeneous microbial composition dominated by clinically significant pathogens.

In Group 2 (children with bronchial asthma without coinfection), the nasopharyngeal microbiota was mainly represented by low-pathogenic and commensal flora. Staphylococcus epidermidis predominated and was detected in approximately 10 children. Other opportunistic microorganisms were identified sporadically and at significantly lower frequencies compared to Group 1.

In Group 3 (healthy control group), the nasopharyngeal microbiota was dominated by normal commensal flora. Neisseria species and Corynebacterium species were most frequently isolated, reflecting a balanced and stable microbial ecosystem typical of healthy children.

Table 1.

Nasopharyngeal microbiota composition in study groups

Analysis of antimicrobial resistance revealed marked differences between the groups. In Group 1, nearly half of the isolated strains demonstrated high-level resistance to β-lactam antibiotics, while resistance to macrolides and tetracyclines was also frequently observed. These differences were statistically significant (p < 0.05). In Group 2, antimicrobial resistance was present but occurred at a considerably lower frequency and was mainly limited to single antibiotic classes. In contrast, no clinically significant antimicrobial resistance was detected among isolates from the healthy control group.

Table 2.

Antimicrobial resistance patterns of isolated microorganisms (%)

Discussion. The findings of the present study confirm that the clinical course of bronchial asthma in children is closely associated not only with immuno-allergic mechanisms but also with alterations in the nasopharyngeal microbiota and the presence of coinfections. Children with bronchial asthma accompanied by coinfection demonstrated a pronounced shift in microbial composition toward clinically significant pathogenic microorganisms.

In the group of asthmatic children with coinfection, the predominance of Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus indicates an increased microbial burden and supports the concept of respiratory dysbiosis contributing to disease exacerbation. These pathogens are known to enhance airway inflammation, disrupt epithelial barrier function, and promote bronchial hyperresponsiveness, thereby worsening asthma control. The detection of fungal microorganisms further suggests immune dysregulation and impaired local defense mechanisms in this patient population.

In contrast, children with bronchial asthma without coinfection exhibited a microbiota composition dominated by low-pathogenic and commensal bacteria, particularly Staphylococcus epidermidis. This finding suggests a relatively preserved microbial balance, which may partially explain the milder disease course and reduced frequency of severe exacerbations observed in the absence of active coinfection.

The healthy control group showed a stable predominance of normal commensal flora, including Neisseria and Corynebacterium species, reflecting an intact and balanced nasopharyngeal ecosystem. These microorganisms are considered essential for maintaining mucosal immunity and preventing colonization by pathogenic species.

Antimicrobial resistance analysis revealed significantly higher resistance rates in the coinfection group, particularly against β-lactam antibiotics, followed by macrolides and tetracyclines. This observation is consistent with global data highlighting the impact of frequent and sometimes inappropriate antibiotic use in children with recurrent respiratory infections. Increased antimicrobial resistance in asthmatic children with coinfection may complicate treatment strategies, reduce therapeutic efficacy, and contribute to prolonged or recurrent disease exacerbations.

Overall, the results emphasize the importance of considering respiratory microbiota composition and antimicrobial resistance patterns in the comprehensive management of pediatric bronchial asthma. Targeted microbiological monitoring may help optimize antibiotic selection and reduce the risk of further resistance development.

Conclusion. The results of this study demonstrate that bronchial asthma in children, particularly when accompanied by coinfection, is associated with significant alterations in the nasopharyngeal microbiota and increased antimicrobial resistance. Asthmatic children with coinfection showed a predominance of clinically relevant pathogenic microorganisms and higher resistance to commonly used antibiotic classes, whereas children without coinfection and healthy controls exhibited a more balanced microbial profile.

These findings underline the clinical relevance of assessing nasopharyngeal microbiota composition and antimicrobial susceptibility in children with bronchial asthma. Incorporating microbiological monitoring into routine clinical practice may support rational antibiotic use, improve individualized treatment strategies, and contribute to better disease control and long-term outcomes in pediatric asthma patients.

Further large-scale and longitudinal studies are warranted to clarify the causal relationships between respiratory microbiota, coinfection, antimicrobial resistance, and asthma severity, as well as to explore potential microbiota-targeted therapeutic approaches.

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