Table 1.

Microbiota profiling in asthmatic and healthy individuals.

Sample method	Population	Asthmatic subjects	Healthy controls (Ref)
Superior airway
Nasopharyngeal aspirateS	Infants (0–12 months) n = 234	Increased Streptococcus. Strong asthma predictor. Streptococcus, Moraxella, or Haemophilus marked virus-associated with acute respiratory infections in asthma.	Dominated by Staphylococcus (41%) and Corynebacterium (22%). Antibiotic usage in the four weeks prior to sampling was associated with higher abundances of Haemophilus, Streptococcus, and Moraxella and lower abundances of Alloiococcus and Corynebacterium (Teo et al., 2015).
Nasal swabS	Children and adolescents (6–20 years) n = 14	Increased Moraxella Catarrhalis, Escherichia and Psychrobacter. Dominated by M. Catarrahalis and less diverse.	M. catarrhalis less abundant Corynebacterium tuberculostearicum. Found in high abundance (Castro-Nallar et al., 2015).
Nasal swabS	Adults (35.8 +/− 16) n = 72	Increased Bacteroidetes (Prevotella), Proteobacteria (Alkanindiges), Actinobacteria (Gardnerella).	Less Proteobacteria and Bacteroidetes (Fazlollahi et al., 2018).
Nasopharyngeal swabS	Elderly (<60 years) n = 40	Higher relative abundance of Moraxella. Higher abundance of Proteobacteria.	Higher relative abundance of Corynebacteriales (Lee et al., 2019).
Oropharyngeal swabS	Elderly (53.4+/− 17.1//55 +/− 13) n = 47	Proteobacteria (Pseudomonas s) and Firmicutes (Lactobacillus spp) are the most dominant populations in asthmatic subjects, these microorganisms not detected in healthy subjects.	Proteobacteria (Pseudomonas) and Firmicutes (Lactobacillus spp) no detected in healthy subjects Bacteroidetes (Streptococcus, Veillonella, Prevotella, and Neisseria) dominant in healthy oropharynx (Park et al., 2014).
Hypopharyngeal aspirate C	Neonates (~1 month) n = 321	Neonates colonized with Streptococcus pneumoniae, M. catarrhalis, Haemophilus influenzae showed increased asthma prevalence at 5 years.	Neonates not colonized with S. pneumoniae, M. catarrhalis or H. influenzae show less risk of a first wheezy episode (Bisgaard et al., 2007).
Hypopharyngeal aspirateS	Children (12–36 months) n = 68	Increase abundance of Moraxella, Haemophilus and Streptococcus, being Moraxella the predominant genera with mean relative abundance of 43.63%.	No healthy control was included (Thorsen et al., 2021).
Broncho-alveolar lavage (BAL)S	Children (11.8 +/− 2.8 years) n = 20	Increase Proteobacteria (Haemophilus) and Firmicutes (Streptococcus) in asthmatic children.	Increase Bacteroidetes (Prevotella) in healthy subjects (Hilty et al., 2010).
Inferior airway
Broncho-alveolar lavage (BAL)S	Children (11.8 +/− 2.8 years) n = 20	Increase Proteobacteria (Haemophilus) and Firmicutes (Streptococcus) in asthmatic children.	Increase Bacteroidetes (Prevotella) in healthy subjects (Hilty et al., 2010).
SputumS	Adults (39–62 years) n = 97	Main species present in airway of healthy and asthmatics patients include Streptococcus Mitis, Streptococcus Aliviarus and Veillonella Dispar.	Airway microbiota similar to asthmatic patients. No differences in airway diversity between asthmatic patients and healthy controls in the composition of microbiota (Ham et al., 2021).
Bronchial brushing S	Adults (20–63 years) n = 40	Increased Bacteroidetes and Firmicutes in severe asthma. Increased Actinobacteria (Mycobacteria, Streptomyces) and proteobacteria (Klebsiella).	Less abundant in Proteobacteria (Klebsiella) (Huang et al., 2015).
Induced sputumS	Adults (age 56–59) n = 167	Significant decrease of alpha diversity in neutrophilic phenotypes High abundance of Moraxella and Haemophilus in neutrophilic phenotypes. Negative correlation of sputum neutrophil percentages with Gemella, Porphyromonas and Streptococcus Taxa.	No healthy control was included (Taylor et al., 2018).
Gut
Broncho-alveolar lavage (BAL)S	Children 11.8 +/− 2.8 years) n = 20	Increase Proteobacteria (Haemophilus) and Firmicutes (Streptococcus) in asthmatic children.	Increase Bacteroidetes (Prevotella) in healthy subjects (Hilty et al., 2010).
Fresh stoolS	Adults (18–50 years) n = 67	Lower alpha diversity enrichment of Ruminococcus gnavus, Clostridium clostridioforme, and Bifidobacterium pseudocatenulatum Depletion of Roseburia intestinalis and Roseburia inulinivorans.	Richer alpha diversity Enrichment of Roseburia inulinivorans and Clostridium disporicum (Zou et al., 2021).
Fecal stoolS	Adults (39–62 years) n = 97	At genus level, the leading bacteria are Prevotella, Bacteroides, Faecalibacterium, and Rominococcus. The most common species were Prevotella Copri, Faecalibacterium prausnitzii, and Bacteroides Plebeius.	Similar to asthmatic patients. There were no significant differences between groups or associations between gut microbiota composition and asthma (Ham et al., 2021).

This table shows the microbial diversity in patients with asthma compared to other study groups, considering different life stages and respiratory/gut tract locations. Analysis Method. S: 16S rRNA gene sequencing. C: Culture. Ref.: Reference.