Reid, DW and Latham, R and Lamont, IL and Camara, M and Roddam, LF, Molecular analysis of changes in Pseudomonas aeruginosa load during treatment of a pulmonary exacerbation in cystic fibrosis, Journal of Cystic Fibrosis, 12, (6) pp. 688-699. ISSN 1569-1993 (2013) [Refereed Article]
Copyright 2013 European Cystic Fibrosis Society
Background: Intravenous antibiotics for pulmonary exacerbations (PEs) of cystic fibrosis (CF) usually target Pseudomonas aeruginosa. Insights into the CF lung microbiome have questioned this approach. We used RT-qPCR to determine whether intravenous antibiotics reduced P. aeruginosa numbers and whether this correlated with improved lung function. We also investigated antibiotic effects on other common respiratory pathogens in CF.
Methods: Sputa were collected from patients when stable and again during a PE. Sputa were expectorated into a RNA preservation buffer for RNA extraction and preparation of cDNA. qPCR was used to enumerate viable P. aeruginosa as well as Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Burkholderia cepacia complex and Aspergillus fumigatus.
Results: Fifteen CF patients were followed through 21 PEs. A complete set of serial sputum samples was unavailable for two patients (three separate PEs). P. aeruginosa numbers did not increase immediately prior to a PE, but numbers during intravenous antibiotic treatment were reduced ≥ 4-log in 6/18 and ≥ 1-log in 4/18 PEs. In 7/18 PEs, P. aeruginosa numbers changed very little with intravenous antibiotics and one patient demonstrated a ≥ 2-log increase in P. aeruginosa load. H. influenzae and S. pneumoniae were detected in ten and five PEs respectively, but with antibiotic treatment these bacteria rapidly became undetectable in 6/10 and 4/5 PEs, respectively. There was a negative correlation between P. aeruginosa numbers and FEV1 during stable phase (rs = 0.75, p < 0.05), and reductions in P. aeruginosa load with intravenous antibiotic treatment correlated with improved FEV1 (rs = 0.52, p <0.05).
Conclusions: Exacerbations are not due to increased P. aeruginosa numbers in CF adults. However, lung function improvements correlate with reduced P. aeruginosa burden suggesting that current antibiotic treatment strategies remain appropriate in most patients. Improved understanding of PE characterised by unchanged P. aeruginosa numbers and minimal lung function improvement following treatment may allow better targeted therapies.
|Item Type:||Refereed Article|
|Keywords:||cystic fibrosis, pseudomonas|
|Research Division:||Biomedical and Clinical Sciences|
|Research Group:||Medical microbiology|
|Research Field:||Medical bacteriology|
|Objective Group:||Clinical health|
|Objective Field:||Clinical health not elsewhere classified|
|UTAS Author:||Reid, DW (Dr David Reid)|
|UTAS Author:||Latham, R (Mr Roger Latham)|
|UTAS Author:||Roddam, LF (Dr Louise Roddam)|
|Funding Support:||National Health and Medical Research Council (544915)|
|Web of Science® Times Cited:||15|
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