NICE, FRANCE — New research suggests that the prevalence of Pseudomonas aeruginosa is higher in patients hospitalized for acute chronic obstructive pulmonary disease exacerbation than in ambulatory patients.
Presence of the gram-negative bacterium in sputum was associated with worse functional outcomes and with a strong history of smoking in a study of 188 hospitalized COPD patients, Dr. Carolina Garcia Vidal said at the 16th European Congress of Clinical Microbiology and Infectious Diseases.
Previous studies have reported prevalence rates for P. aeruginosa (PA) ranging from 0.5% to 15% in ambulatory patients.
In one published study, PA was identified in 5.5% of sputum of 118 patients hospitalized with acute exacerbation of COPD with concomitant pneumonia (Intern. Med. J. 2005;35:661–7). In the current study, 23% of cultures were positive for PA.
Dr. Garcia Vidal, of the Hospital de Bellvitge in Barcelona, and her associates prospectively studied 188 consecutive patients admitted to a 450-bed university hospital between June 2003 and September 2004 with an acute exacerbation of COPD, excluding patients with asthma or bronchitis as their primary diagnosis.
Sputum cultures were taken at admission. Patients were followed for 1 year, and spirometry was performed 1 month after discharge.
Among those patients, 32 (17%) had a hospital admission in the previous month; 116 (62%) had taken antimicrobials in the previous 3 months; and 106 (56%) had bronchiectasis. Their mean age was 72 years, and 95% were male.
A total of 106 patients were readmitted for another episode of acute exacerbation. A valid sputum culture was collected in 220 of 469 episodes. One microorganism was present in 117 episodes, two microorganisms in 93, and three in 10 episodes.
P. aeruginosa was present in 51 (23%) cultures, Haemophilus influenzae in 24 (11%), Streptococcus pneumoniae in 21 (9.5%), Enterobacteriaceae in 8 (4%), and normal flora in 159 (72%). Patients with bacterial infection had a forced expiratory volume in 1 second (FEV1) significantly lower than those with negative sputum cultures, she said.
The presence of P. aeruginosa in patients was associated with a significantly lower FEV1 (37.9 vs. 42.7), significantly worse 6-minute walking test (207 meters vs. 324 meters), and significantly greater oxygen use at home (44% vs. 22%).
History of pack-years of smoking was significantly higher in PA patients than in non-PA patients (80.2 vs. 56.2).
P. aeruginosa was resistant to ciprofloxacin in only three patients. “The majority of P. aeruginosa isolates remain susceptible to fluoroquinolones, and these drugs should be considered in the empirical treatment of COPD exacerbations in patients admitted to the hospital with a history of previous smoking and severe functional impairment,” said Dr. Garcia Vidal.