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Changes in prevalence and load of airway bacteria using quantitative PCR in stable and exacerbated COPD.
Thorax 2012; 67(12):1075-80T

Abstract

BACKGROUND

Prevalence and load of airway bacteria in stable and exacerbated chronic obstructive pulmonary disease (COPD) has been previously studied using microbiological culture. Molecular techniques, such as quantitative PCR (qPCR), may be more informative.

METHODS

In this study, 373 sputum samples from 134 COPD outpatients were assessed for prevalence and load of typical airway bacteria (Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis) by multiplex qPCR, with 176 samples analysed for atypical bacteria. Paired stable and exacerbation typical bacteria data were compared in 52 patients. We compared routine culture with qPCR in 177/373 samples.

RESULTS

Typical bacteria were more prevalent in exacerbation than stable-state paired samples: 30/52 (57.7%) vs. 14/52 (26.9%); p=0.001. In patients who were bacteria-positive at both time points, mean (±1 SEM) load was significantly higher at exacerbation than stable state (108.5(±0.3) vs. 107.2(±0.5) cfu/ml), constituting a 20-fold increase (p=0.011). qPCR was more discriminatory at detecting typical bacteria than microbiological culture (prevalence 59.3% vs. 24.3%; p<0.001). At stable state, higher airway bacterial load correlated with more severe airflow limitation (FEV(1)%predicted) (r=-0.299; p=0.033) and higher inhaled corticosteroid dosage (r=0.382; p=0.008). Mean C-reactive protein was higher in bacterial-associated exacerbations (35.0 Vs 25.1 mg/L; p=0.032).

CONCLUSIONS

Airway bacterial prevalence and load increase at COPD exacerbations and are an aetiological factor. qPCR is more discriminatory than culture, identifying higher airway bacterial prevalence. Exacerbations associated with bacterial detection showed a higher mean C-reactive protein level. In the stable state, airway bacterial load is related to more severe airflow limitation and higher inhaled corticosteroid dosage used.

Authors+Show Affiliations

Centre for Respiratory Medicine, University College London, London, UK. davinder.garcha.09@ucl.ac.ukNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22863758

Citation

Garcha, Davinder S., et al. "Changes in Prevalence and Load of Airway Bacteria Using Quantitative PCR in Stable and Exacerbated COPD." Thorax, vol. 67, no. 12, 2012, pp. 1075-80.
Garcha DS, Thurston SJ, Patel AR, et al. Changes in prevalence and load of airway bacteria using quantitative PCR in stable and exacerbated COPD. Thorax. 2012;67(12):1075-80.
Garcha, D. S., Thurston, S. J., Patel, A. R., Mackay, A. J., Goldring, J. J., Donaldson, G. C., ... Wedzicha, J. A. (2012). Changes in prevalence and load of airway bacteria using quantitative PCR in stable and exacerbated COPD. Thorax, 67(12), pp. 1075-80. doi:10.1136/thoraxjnl-2012-201924.
Garcha DS, et al. Changes in Prevalence and Load of Airway Bacteria Using Quantitative PCR in Stable and Exacerbated COPD. Thorax. 2012;67(12):1075-80. PubMed PMID: 22863758.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Changes in prevalence and load of airway bacteria using quantitative PCR in stable and exacerbated COPD. AU - Garcha,Davinder S, AU - Thurston,Sarah J, AU - Patel,Anant R C, AU - Mackay,Alexander J, AU - Goldring,James J P, AU - Donaldson,Gavin C, AU - McHugh,Timothy D, AU - Wedzicha,Jadwiga A, Y1 - 2012/08/03/ PY - 2012/8/7/entrez PY - 2012/8/7/pubmed PY - 2013/2/12/medline SP - 1075 EP - 80 JF - Thorax JO - Thorax VL - 67 IS - 12 N2 - BACKGROUND: Prevalence and load of airway bacteria in stable and exacerbated chronic obstructive pulmonary disease (COPD) has been previously studied using microbiological culture. Molecular techniques, such as quantitative PCR (qPCR), may be more informative. METHODS: In this study, 373 sputum samples from 134 COPD outpatients were assessed for prevalence and load of typical airway bacteria (Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis) by multiplex qPCR, with 176 samples analysed for atypical bacteria. Paired stable and exacerbation typical bacteria data were compared in 52 patients. We compared routine culture with qPCR in 177/373 samples. RESULTS: Typical bacteria were more prevalent in exacerbation than stable-state paired samples: 30/52 (57.7%) vs. 14/52 (26.9%); p=0.001. In patients who were bacteria-positive at both time points, mean (±1 SEM) load was significantly higher at exacerbation than stable state (108.5(±0.3) vs. 107.2(±0.5) cfu/ml), constituting a 20-fold increase (p=0.011). qPCR was more discriminatory at detecting typical bacteria than microbiological culture (prevalence 59.3% vs. 24.3%; p<0.001). At stable state, higher airway bacterial load correlated with more severe airflow limitation (FEV(1)%predicted) (r=-0.299; p=0.033) and higher inhaled corticosteroid dosage (r=0.382; p=0.008). Mean C-reactive protein was higher in bacterial-associated exacerbations (35.0 Vs 25.1 mg/L; p=0.032). CONCLUSIONS: Airway bacterial prevalence and load increase at COPD exacerbations and are an aetiological factor. qPCR is more discriminatory than culture, identifying higher airway bacterial prevalence. Exacerbations associated with bacterial detection showed a higher mean C-reactive protein level. In the stable state, airway bacterial load is related to more severe airflow limitation and higher inhaled corticosteroid dosage used. SN - 1468-3296 UR - https://www.unboundmedicine.com/medline/citation/22863758/Changes_in_prevalence_and_load_of_airway_bacteria_using_quantitative_PCR_in_stable_and_exacerbated_COPD_ L2 - http://thorax.bmj.com/cgi/pmidlookup?view=long&amp;pmid=22863758 DB - PRIME DP - Unbound Medicine ER -