[Microbiological Characterization of Exacerbations in Severe Asthma and Their Impact on Therapeutic Decision-Making]

Severe asthma (SA) exacerbations impose a substantial healthcare burden. Microbiological characterization using molecular techniques may improve pathogen identification and contribute to a more individualized therapeutic approach.

To characterize the microbiological profile of exacerbations in patients with severe asthma and to analyze the prescription patterns for antibiotics (ATB) and systemic corticosteroids (SC).

This retrospective observational study was conducted in a Severe Asthma Unit. A total of 103 exacerbations were investigated using conventional microbiological methods and multiplex polymerase chain reaction (FilmArray™) performed on respiratory samples. Bacterial findings were classified according to operational criteria compatible with infection or colonization based on genomic load and culture results. Associations between clinical, microbiological, and therapeutic variables were explored using univariate analyses.

Microbiological detection was achieved in 78.6% of exacerbations. Viruses were identified in 59.2% of episodes, with rhinovirus representing the predominant pathogen (62.3% of viral detections). Bacteria were identified in 53.4% of exacerbations (H. influenzae 36,6%), frequently in association with viral coinfection. Bronchiectasis was associated with a higher probability of bacterial detection (OR 2.50; p = 0.031). ATB and SC were prescribed in 61.2% and 44.6% of exacerbations, respectively, with frequent use of combination therapy. No significant differences in overall microbiological detection rates were observed according to biologic therapy status. Considerable microbiological variability was observed across recurrent exacerbations in the same patient.

Microbiological findings were common during severe asthma exacerbations, with respiratory viruses, particularly rhinovirus, being the most frequently identified pathogens. Bronchiectasis was associated with higher rates of bacterial detection and ATB use. The marked variability observed between episodes supports the potential value of individualized microbiological assessment during exacerbations and warrants prospective studies aimed at optimizing therapeutic decision-making.