title: The importance of bacterial and viral infections associated with adult asthma exacerbations in clinical practice.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Motoyasu
authors.initials: M
authors.lastname: Iikura
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hojo
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Rikiya
authors.initials: R
authors.lastname: Koketsu
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Ayano
authors.initials: A
authors.lastname: Sato
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Chino
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Shoki
authors.initials: S
authors.lastname: Ro
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Haruna
authors.initials: H
authors.lastname: Masaki
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Hirashima
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Ishii
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Naka
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Jin
authors.initials: J
authors.lastname: Takasaki
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Shinyu
authors.initials: S
authors.lastname: Izumi
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kobayashi
authors.affiliation: Laboratory of Systems Biology, Center for Experimental Medicine and Systems Biology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Laboratory of Systems Biology, Center for Experimental Medicine and Systems Biology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan; Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Nakae
authors.affiliation: Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Haruhito
authors.initials: H
authors.lastname: Sugiyama
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001249:Asthma / Q000150:complications / Q000453:epidemiology / Q000382:microbiology* / Q000821:virology*; D001424:Bacterial Infections / Q000150:complications*; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009305:Nasopharynx / Q000382:microbiology / Q000821:virology; D011014:Pneumonia / Q000453:epidemiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology; D014777:Virus Diseases / Q000150:complications*