Yield of sputum microbiological examination in patients hospitalized for exacerbations of chronic obstructive pulmonary disease with purulent sputum

Abstract

Background: Whether sputum microbiological examination should be performed systematically in hospitalized patients with chronic obstructive pulmonary disease (COPD) exacerbations remains unclear.

Objectives: To assess the yield of sputum microbiological examination in COPD patients hospitalized in a medical ward for an acute exacerbation with purulent sputum.

Methods: Two hundred consecutive exacerbations in 118 patients were studied. Patients underwent sputum microbiological examination on admission and baseline lung function tests and CT scans were recorded. Factors associated with positive culture were analyzed.

Results: Sputum culture was positive (>or=10(7) CFU/ml) in 59% of samples, Haemophilus influenzae and Streptococcus pneumoniae being the most frequent pathogens. Factors associated with positive culture were bronchiectasis, long-term oxygen therapy and low FEV1. Pseudomonas spp. were found in 8.5% of all patients, who all had a FEV1<50% of predicted and were older. Only 25% of sputum samples satisfied all quality criteria. Sputum culture was positive in a high proportion of these samples (80.5%), but also in one half of samples with >25 leukocytes but >10 epithelial cells per field. Microbiological results induced a change in antibiotic therapy in 43.9% of cases with both quality criteria but also in 25.2% of cases with only one quality criterion. Finally, a predominant aspect after Gram stain was found in all positive samples.

Conclusions: These data suggest that sputum microbiological examination with direct examination and leukocyte count should be performed routinely in patients hospitalized for COPD exacerbations with purulent sputum, especially when FEV1 is less than 50% predicted and in patients with bronchiectasis.