Source: Annual Congress 2008 - Mechanisms of respiratory infections: interaction between the pathogen and the host
Disease area: Airway diseases, Respiratory infections

Abstract

Recent studies have suggested that bacteria may play important roles in the asthmatic lung. By extension, it is important to detail what bacteria are present accurately and without bias. Here, our hypothesis was that the airways of severe asthmatic patients would contain potentially pathogenic or immunologically relevant bacterial species. To test this, a molecular approach that extracted nucleic acids from 24 induced sputa or bronchoalveolar lavage samples from 23 stable severe asthmatic patients was used. Bacterial ribosomal genes were amplified from these nucleic acids and analysed by Terminal Restriction Fragment Length Polymorphism (T-RFLP). In every case, bacteria were detected, with an average of 7.7 (± 4.5) species detected per sample. On average, T-RF bands with the first and second highest volume represented 58.5% and 17.3% of the total profile volume respectively. Clone sequence analysis identified a total of 23 distinct bacterial species in 115 ribosomal genes cloned from 5 patients. The species identified in descending rank order were Moraxella catarrhalis, Neisseria sp., Veillonella sp., Prophyromonas sp., Prevotella sp., Terrahaemophilus aromaticivorans, Pseudomonas aeruginosa, Streptococcus sp., and Haemophilus sp., As hypothesised, certain of these species can act as respiratory pathogens. Moreover, many species detected have not previously been reported in asthmatic lungs. Whilst more is needed to assess the significance of these bacteria as determinants in the persistence and severity of disease expression, this research highlights the potential importance of abnormal airway bacterial colonisation in asthma and may direct future treatment approaches for disease control.

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Citations should be made in the following way:
S. Wiriyachaiporn, B. Green, V. Kehagia, M. Carroll, P. Howarth, K. Bruce (London, Southampton, United Kingdom). Molecular characterisation of bacteria in sputum samples from severe asthma. Eur Respir J 2008; 32: Suppl. 52, 2291

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