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Airway bacterial concentrations and exacerbations of chronic obstructive pulmonary disease.
Am J Respir Crit Care Med 2007; 176(4):356-61AJ

Abstract

RATIONALE

Increased bacterial concentration (load) in the lower airways and new bacterial strain acquisition have been posited as mechanisms for chronic obstructive pulmonary disease (COPD) exacerbations. Bacterial concentrations are higher during exacerbation than during stable disease; however, these studies are cross sectional and devoid of strain typing.

OBJECTIVES

To determine if the increased bacterial concentrations function as a separate mechanism for exacerbation induction independent of new strain acquisition.

METHODS

In a prospective, longitudinal cohort of patients with COPD, the relationship between exacerbation occurrence, sputum bacterial concentrations, and new strain acquisition was examined.

MEASUREMENTS AND MAIN RESULTS

Clinical information, quantitative sputum cultures, and molecular typing of potential bacterial pathogen isolates. Over 81 months, 104 subjects completed 3,009 clinic visits, 560 (19.6%) during exacerbations and 2,449 (80.4%) during stable disease. Among preexisting strains, sputum concentrations of Nontypeable Haemophilus influenzae and Haemophilus haemolyticus were not different in exacerbation versus stable disease. Moraxella catarrhalis (stable, 10(8.38 +/- 0.13) [mean +/- SEM] vs. exacerbation, 10(7.78 +/- 0.26); p = 0.02) and Streptococcus pneumoniae (stable, 10(8.42 +/- 0.21) vs. exacerbation, 10(7.76 +/- 0.52); p = 0.07) concentrations were lower during exacerbations compared with stable periods. Concentrations of new strains of H. influenzae (stable, 10(7.28 +/- 0.15) vs. exacerbation, 10(7.76 +/- 0.17); p = 0.04) and M. catarrhalis (stable, 10(7.85 +/- 0.15) vs. exacerbation, 10(8.37 +/- 0.14); p = 0.02), were increased during exacerbations; however, the differences were small.

CONCLUSIONS

Change in bacterial load is unlikely to be an important mechanism for exacerbations. Better understanding of the host-pathogen interaction, rather than enumerating bacteria in respiratory samples, is required to provide new insights into bacterial infection in COPD.

Authors+Show Affiliations

Veterans Affairs Western New York Healthcare System (151), 3495 Bailey Avenue, Buffalo, NY 14215, USA. ssethi@buffalo.eduNo 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, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

17478618

Citation

Sethi, Sanjay, et al. "Airway Bacterial Concentrations and Exacerbations of Chronic Obstructive Pulmonary Disease." American Journal of Respiratory and Critical Care Medicine, vol. 176, no. 4, 2007, pp. 356-61.
Sethi S, Sethi R, Eschberger K, et al. Airway bacterial concentrations and exacerbations of chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2007;176(4):356-61.
Sethi, S., Sethi, R., Eschberger, K., Lobbins, P., Cai, X., Grant, B. J., & Murphy, T. F. (2007). Airway bacterial concentrations and exacerbations of chronic obstructive pulmonary disease. American Journal of Respiratory and Critical Care Medicine, 176(4), pp. 356-61.
Sethi S, et al. Airway Bacterial Concentrations and Exacerbations of Chronic Obstructive Pulmonary Disease. Am J Respir Crit Care Med. 2007 Aug 15;176(4):356-61. PubMed PMID: 17478618.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Airway bacterial concentrations and exacerbations of chronic obstructive pulmonary disease. AU - Sethi,Sanjay, AU - Sethi,Rohin, AU - Eschberger,Karen, AU - Lobbins,Phyllis, AU - Cai,Xueya, AU - Grant,Brydon J B, AU - Murphy,Timothy F, Y1 - 2007/05/03/ PY - 2007/5/5/pubmed PY - 2007/10/6/medline PY - 2007/5/5/entrez SP - 356 EP - 61 JF - American journal of respiratory and critical care medicine JO - Am. J. Respir. Crit. Care Med. VL - 176 IS - 4 N2 - RATIONALE: Increased bacterial concentration (load) in the lower airways and new bacterial strain acquisition have been posited as mechanisms for chronic obstructive pulmonary disease (COPD) exacerbations. Bacterial concentrations are higher during exacerbation than during stable disease; however, these studies are cross sectional and devoid of strain typing. OBJECTIVES: To determine if the increased bacterial concentrations function as a separate mechanism for exacerbation induction independent of new strain acquisition. METHODS: In a prospective, longitudinal cohort of patients with COPD, the relationship between exacerbation occurrence, sputum bacterial concentrations, and new strain acquisition was examined. MEASUREMENTS AND MAIN RESULTS: Clinical information, quantitative sputum cultures, and molecular typing of potential bacterial pathogen isolates. Over 81 months, 104 subjects completed 3,009 clinic visits, 560 (19.6%) during exacerbations and 2,449 (80.4%) during stable disease. Among preexisting strains, sputum concentrations of Nontypeable Haemophilus influenzae and Haemophilus haemolyticus were not different in exacerbation versus stable disease. Moraxella catarrhalis (stable, 10(8.38 +/- 0.13) [mean +/- SEM] vs. exacerbation, 10(7.78 +/- 0.26); p = 0.02) and Streptococcus pneumoniae (stable, 10(8.42 +/- 0.21) vs. exacerbation, 10(7.76 +/- 0.52); p = 0.07) concentrations were lower during exacerbations compared with stable periods. Concentrations of new strains of H. influenzae (stable, 10(7.28 +/- 0.15) vs. exacerbation, 10(7.76 +/- 0.17); p = 0.04) and M. catarrhalis (stable, 10(7.85 +/- 0.15) vs. exacerbation, 10(8.37 +/- 0.14); p = 0.02), were increased during exacerbations; however, the differences were small. CONCLUSIONS: Change in bacterial load is unlikely to be an important mechanism for exacerbations. Better understanding of the host-pathogen interaction, rather than enumerating bacteria in respiratory samples, is required to provide new insights into bacterial infection in COPD. SN - 1073-449X UR - https://www.unboundmedicine.com/medline/citation/17478618/Airway_bacterial_concentrations_and_exacerbations_of_chronic_obstructive_pulmonary_disease_ L2 - http://www.atsjournals.org/doi/full/10.1164/rccm.200703-417OC?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -