Characterising the Microbiota in Asthma
Condition: Asthma
MeSH terms: Asthma
Study type: Observational

Summary: 
      Previous work has determined that there are significant differences in the communities of
      bacteria found in the airways of asthmatic patients compared to those found in the airways of
      healthy people.

      It is not yet clear if these bacterial communities are similar in all patients with asthma or
      if they are different in people with more severe asthma, with different types of asthma or
      between asthma patients taking different treatment. This is important to know as any
      differences in the bacteria present between groups may help to explain why people with asthma
      do not have the same features of disease.

      This research aims to determine if there are any differences in the number and type of
      bacteria found in the airways of asthmatic patients (1) with different severities of asthma
      and (2) who use different types of inhaled steroid treatment for asthma.

      We will do this by detecting the DNA of bacteria present in phlegm samples from these
      patients. We will also take measurements of the different components of asthma to see if the
      bacteria are different in people with different types of disease.

      As it is not yet clear if the bacteria detected in phlegm samples from one person may differ
      on different occasions, we will be taking more than one sample from some patients to see how
      similar this is over time.
    

Detailed description: 
      The main aim of this project is to determine if microbiota composition is correlated with
      disease severity (as determined by BTS step). Although initial studies suggest that
      asthmatics of different severities may have similar microbiota composition, there is no
      direct evidence to support this assertion. Also, the three main studies in this area so far
      have all used different sequencing methods, making comparisons difficult.

      The relationship between the microbiota composition of different subjects and clinical
      measures including bronchial hyperreactivity (as measured by methacholine challenge) and
      pattern of airway inflammation (as measured by sputum differential cell count and exhaled
      nitric oxide levels) will be investigated further. Comparisons will also be made between
      samples from asthmatic patients using the inhaled steroid fluticasone and those using
      budesonide, as there is evidence suggesting that fluticasone leads to an increased risk of
      pneumonia and non tuberculous mycobacterial disease in certain patient groups. Unpublished
      data (Astra Zeneca) suggests the excess risk of pneumonia with fluticasone compared to
      budesonide may be more pronounced after at least 12 months of treatment with inhaled
      corticosteroid. Microbiota composition of the sputum samples will be evaluated in conjunction
      with standard microbiological culture of these samples to allow a comparison between these
      two methods.

      In order to assess the reproducibility of the induced sputum method for assessing the lung
      microbiota, a repeat sputum sample will be taken from a subgroup of 20 patients within 24
      hours of the collection of the first sample and compared. A further sample will be taken from
      this subgroup of patients 2 weeks later to assess the longitudinal stability of the bacterial
      population.
    

Intervention name(s): Inhaled corticosteroid dose/type
Intervention type(s): Drug
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Adult asthmatic patients on Step 2 or Step 4 of the British Thoracic Society Asthma
        stepwise management protocol for asthma whose details are stored on the Nottingham
        Respiratory Research Patient Database or who attend respiratory clinics at the Nottingham
        City Hospital
      
Biospecimen description: 
      Sputum samples to be retained containing bacterial DNA
    
Keywords: Microbiota