Study objectives: To investigate the possible
relationship between functional respiratory impairment measured by
FEV1 and isolation of diverse pathogens in the sputum of
patients with exacerbations of COPD.
Multicenter, cross-sectional, epidemiologic study.
Setting: Pneumology units in six secondary or tertiary
hospitals in Spain.
Patients: Ninety-one patients with
acute exacerbation of COPD were included.
Interventions: A quantitative sputum culture was performed,
and bacterial growth was considered significant only when the germ was
isolated at concentrations > 106 cfu (> 105
for Streptococcus pneumoniae) in samples with < 10
epithelial cells and > 25 leukocytes per low magnification field
Results: Germs isolated were the following:
Haemophilusinfluenzae (20 cases;
22%), Pseudomonasaeruginosa (14
cases; 15%), S pneumoniae (9 cases; 10%),
Moraxellacatarrhalis (8 cases;
9%), other Gram-negative bacteria (7 cases; 7%), and non-potentially
pathogenic microorganisms (non-PPMs; 33 cases; 36%). P
aeruginosa and H influenzae were isolated more
frequently among the patients with FEV1 < 50% than
among those with FEV1 > 50% (p < 0.05). All patients
with P aeruginosa in sputum had
FEV1 < 1,700 mL. FEV1 < 50% was
associated with a very high risk of P aeruginosa or
H influenzae isolation: the odds ratios (ORs) are 6.62
(95% confidence interval [CI], 1.2 to 123.6) and 6.85 (95% CI, 1.6
to 52.6), respectively. Furthermore, active tobacco smoking was
associated with a high risk of H influenzae isolation
(OR, 8.1; 95% CI, 1.9 to 43.0).
with the greatest degree of functional impairment, as measured by their
FEV1, presented a higher probability of having an isolation
of P aeruginosa or H influenzae in
significant concentrations in sputum during an exacerbation. The
diagnostic yield of sputum in patients with an
FEV1 > 50% was low, with a predominance of
non-PPMs. Low FEV1 and active tobacco smoking are
data that should be considered when establishing an empiric antibiotic
treatment for exacerbated COPD.