Display Settings:


Send to:

Choose Destination
See comment in PubMed Commons below
Cough. 2012 Sep 14;8(1):5. doi: 10.1186/1745-9974-8-5.

PCR based bronchoscopic detection of common respiratory pathogens in chronic cough: a case control study.

Author information

  • 1Respiratory Research Group, Faculty of Medical and Human Sciences, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK. Jacky.Smith@manchester.ac.uk.



Viral respiratory tract infection is the most frequent cause of acute cough and is reported at onset in about one third of patients with chronic cough. Persistent infection is therefore one possible explanation for the cough reflex hypersensitivity and pulmonary inflammation reported in chronic cough patients.


Bronchoscopic endobronchial biopsies and bronchoalveolar lavage cell counts were obtained from ten healthy volunteers and twenty treatment resistant chronic cough patients (10 selected for lavage lymphocytosis). A screen for known respiratory pathogens was performed on biopsy tissue. Chronic cough patients also underwent cough reflex sensitivity testing using citric acid.


There was no significant difference in incidence of infection between healthy volunteers and chronic cough patients (p = 0.115) or non-lymphocytic and lymphocytic groups (p = 0.404). BAL cell percentages were not significantly different between healthy volunteers and chronic cough patients without lymphocytosis. Lymphocytic patients however had a significantly raised percentage of lymphocytes (p < 0.01), neutrophils (p < 0.05), eosinophils (p < 0.05) and decreased macrophages (p < 0.001) verses healthy volunteers. There was no significant difference in the cough reflex sensitivity between non-lymphocytic and lymphocytic patients (p = 0.536).


This study indicates latent infection in the lung is unlikely to play an important role in chronic cough, but a role for undetected or undetectable pathogens in either the lung or a distal site could not be ruled out.


Current Controlled Trials ISRCTN62337037 & ISRCTN40147207.

Free PMC Article
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for BioMed Central Icon for PubMed Central Icon for International Standard Randomised Controlled Trial Number Register
    Loading ...
    Write to the Help Desk