The importance of bacterial and viral infections associated with adult asthma exacerbations in clinical practice

PLoS One. 2015 Apr 22;10(4):e0123584. doi: 10.1371/journal.pone.0123584. eCollection 2015.


Background: Viral infection is one of the risk factors for asthma exacerbation. However, which pathogens are related to asthma exacerbation in adults remains unclear.

Objective: The relation between various infections and adult asthma exacerbations was investigated in clinical practice.

Methods: The study subjects included 50 adult inpatients due to asthma exacerbations and 20 stable outpatients for comparison. The pathogens from a nasopharyngeal swab were measured by multiplex PCR analysis.

Results: Asthma exacerbations occurred after a common cold in 48 inpatients. The numbers of patients with viral, bacterial, or both infections were 16, 9, and 9, respectively. The dominant viruses were rhinoviruses, respiratory syncytial virus, influenza virus, and metapneumovirus. The major bacteria were S. pneumoniae and H. influenzae. Compared to pathogen-free patients, the patients with pathogens were older and non-atopic and had later onset of disease, lower FeNO levels, lower IgE titers, and a higher incidence of comorbid sinusitis, COPD, or pneumonia. Compared to stable outpatients, asthma exacerbation inpatients had a higher incidence of smoking and comorbid sinusitis, COPD, or pneumonia. Viruses were detected in 50% of stable outpatients, but a higher incidence of rhinovirus, respiratory syncytial virus, and metapneumovirus infections was observed in asthma exacerbation inpatients. H. influenzae was observed in stable asthmatic patients. Other bacteria, especially S. pneumoniae, were important in asthma exacerbation inpatients.

Conclusion: Viral or bacterial infections were observed in 70% of inpatients with an asthma exacerbation in clinical practice. Infection with S. pneumoniae was related to adult asthma exacerbation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Asthma / complications
  • Asthma / epidemiology
  • Asthma / microbiology*
  • Asthma / virology*
  • Bacterial Infections / complications*
  • Comorbidity
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nasopharynx / microbiology
  • Nasopharynx / virology
  • Pneumonia / epidemiology
  • Pulmonary Disease, Chronic Obstructive / epidemiology
  • Virus Diseases / complications*

Grant support

This work was supported by a grant from the National Center for Global Health and Medicine (22-120 MI) and Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency (SN).The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.