Colour of sputum is a marker for bacterial colonisation in chronic obstructive pulmonary disease.
BACKGROUND
Bacterial colonisation in chronic obstructive pulmonary disease (COPD) contributes to airway inflammation and modulates exacerbations. We assessed risk factors for bacterial colonisation in COPD.


METHODS
Patients with stable COPD consecutively recruited over 1 year gave consent to provide a sputum sample for microbiologic analysis. Bronchial colonisation by potentially pathogenic microorganisms (PPMs) was defined as the isolation of PPMs at concentrations of > or =102 colony-forming units (CFU)/mL on quantitative bacterial culture. Colonised patients were divided into high (>105 CFU/mL) or low (<105 CFU/mL) bacterial load.


RESULTS
A total of 119 patients (92.5% men, mean age 68 years, mean forced expiratory volume in one second [FEV1] [% predicted] 46.4%) were evaluated. Bacterial colonisation was demonstrated in 58 (48.7%) patients. Patients with and without bacterial colonisation showed significant differences in smoking history, cough, dyspnoea, COPD exacerbations and hospitalisations in the previous year, and sputum colour. Thirty-six patients (62% of those colonised) had a high bacterial load. More than 80% of the sputum samples with a dark yellow or greenish colour yielded PPMs in culture. In contrast, only 5.9% of white and 44.7% of light yellow sputum samples were positive (P < 0.001). Multivariate analysis showed an increased degree of dyspnoea (odds ratio [OR] = 2.63, 95% confidence interval [CI] 1.53-5.09, P = 0.004) and a darker sputum colour (OR = 4.11, 95% CI 2.30-7.29, P < 0.001) as factors associated with the presence of PPMs in sputum.


CONCLUSIONS
Almost half of our population of ambulatory moderate to very severe COPD patients were colonised with PPMs. Patients colonised present more severe dyspnoea, and a darker colour of sputum allows identification of individuals more likely to be colonised.
Miravitlles
Marc
M
Fundació Clínic, Institut D'Investigacions Biomèdiques August Pi i Sunyer, Ciber de Enfermedades Respiratorias, Barcelona, Spain. marcm@separ.es
Marín
Alicia
A
Monsó
Eduard
E
Vilà
Sara
S
de la Roza
Cristian
C
Hervás
Ramona
R
Esquinas
Cristina
C
García
Marian
M
Millares
Laura
L
Morera
Josep
J
Torres
Antoni
A
D000368:Aged; D000553:Ambulatory Care; D001980:Bronchi / Q000382:microbiology* / Q000503:physiopathology; D015169:Colony Count, Microbial; D003116:Color; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000382:microbiology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000382:microbiology* / Q000503:physiopathology; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D013030:Spain; D013183:Sputum / Q000382:microbiology*; D014797:Vital Capacity
Am J Respir Crit Care Med. 2008 May 1;177(9):1048-9; author reply 1049
18434335
Thorax. 1992 Jan;47(1):25-9
1539140
Eur Respir J. 1997 Oct;10(10):2319-26
9387960
Am J Respir Crit Care Med. 2001 Feb;163(2):349-55
11179105
Thorax. 2002 Oct;57(10):847-52
12324669
Eur Respir J. 1999 Feb;13(2):343-8
10065679
Am J Respir Crit Care Med. 1996 Aug;154(2 Pt 1):308-17
8756799
Eur Respir J. 2009 Nov;34(5):1066-71
19386683
Arch Intern Med. 2005 Apr 25;165(8):891-7
15851640
Thorax. 2008 Jun;63(6):493-9
18057097
Clin Respir J. 2008 Apr;2(2):116-22
20298316
Am J Respir Crit Care Med. 2000 Sep;162(3 Pt 1):947-52
10988111
Thorax. 2002 Jan;57(1):15-9
11809984
Eur Respir J. 1999 Nov;14(5):1015-22
10596683
Am J Respir Crit Care Med. 1995 Oct;152(4 Pt 1):1316-20
7551388
Chest. 2002 May;121(5):1449-55
12006427
Eur Respir J Suppl. 2002 Jul;36:9s-19s
12168752
Am J Med. 2000 Sep;109(4):288-95
10996579
Am J Respir Crit Care Med. 2006 May 1;173(9):991-8
16474030
Am J Respir Crit Care Med. 2006 May 15;173(10):1114-21
16484677
Thorax. 2005 Nov;60(11):925-31
16055622
Eur Respir J. 1999 Feb;13(2):338-42
10065678
N Engl J Med. 2002 Aug 15;347(7):465-71
12181400
Thorax. 2007 Jan;62(1):29-35
16928715
Chest. 2005 Jun;127(6):2231-6
15947342
Am J Respir Crit Care Med. 2003 Apr 15;167(8):1090-5
12684248
Am J Respir Crit Care Med. 2007 Aug 15;176(4):356-61
17478618
Thorax. 2002 Sep;57(9):759-64
12200518
Chest. 2000 Jun;117(6):1638-45
10858396
Eur Respir J. 1997 May;10(5):1137-44
9163659