Antibiotics of little benefit in poorly controlled asthma
MedWire News: Antibiotic treatment does not improve disease control in adults with mild-to-moderate asthma who have failed to respond to low-dose inhaled corticosteroids alone, study results suggest.
"Colonization of the upper and lower airways with typical and atypical bacterial pathogens has been postulated to be an important factor in the development and persistence of asthma," explain E Rand Sutherland (National Jewish Health, Denver, Colorado) and team.
This "has raised the possibility that macrolide antibiotics could be of benefit in patients with persistent asthma and evidence of infection or colonization with these organisms," they add.
To investigate whether treatment with the antibiotic clarithromycin can improve asthma control, the team studied 92 patients with asthma that remained poorly controlled despite 4 weeks of treatment with inhaled corticosteroids (fluticasone propionate).
Airway biopsies were collected from the participants and analyzed using polymerase chain reaction (PCR), which revealed evidence of Mycoplasma pneumonia and/or Chlamydophila pneumonia infection in 12 (13%) patients.
Patients with and without evidence of infection were then randomly assigned to receive 16 weeks of treatment with either clarithromycin or placebo in addition to fluticasone propionate. The Asthma Control Questionnaire was completed by the participants at randomization and at the end of the study period.
The researchers found that in PCR-positive participants, those assigned to take clarithromycin showed a 0.4-unit improvement in ACQ scores over the study period compared with a 0.1-unit improvement in those assigned to placebo - a non-significant between-group difference.
In participants who were PCR-negative, those assigned to take clarithromycin also showed a 0.4-unit improvement in ACQ score compared with a 0.2-unit improvement in those assigned to take placebo. Again, this between-group difference was nonsignificant.
Treatment with clarithromycin was not associated with any improvements in lung function or airway inflammation, but was associated with an improvement in airway hyper-responsiveness, increasing the concentration of methacholine needed to provoke a 20% fall in FEV1 (PC20) by a mean of 1.2 doubling doses.
Sutherland and team conclude in the Journal of Allergy and Clinical Immunology: "Adding clarithromycin to fluticasone in adults with mild-to-moderate persistent asthma that was suboptimally controlled by low-dose inhaled corticosteroids alone did not further improve asthma control."
They add that "further studies are warranted to characterize the role of microbial communities in the asthmatic airway and to determine whether evidence of bacterial colonization or infection in the lower airway is predictive of asthma phenotype or clinical improvement with antibiotic treatment."
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By Mark Cowen