title: Sputum color as a marker of acute bacterial exacerbations of chronic obstructive pulmonary disease.
abstract: We analyzed 795 sputa from 315 patients (233 males, mean age 69.3+/-8.8 years, mean number of exacerbations 2.52/patient) with acute exacerbations of moderate-to-severe chronic obstructive pulmonary disease (COPD) (mean steady-state FEV1 42.5+/-7.8% of predicted). 581/795 sputa were considered adequate. Sputum was analyzed by a quali-quantitative colorimetric scale allowing both color distinction and color degree of intensity. Quantitative culture was then performed (threshold: >10(6)CFU/mL). Samples were distinguished in mucoid (145) and purulent (436) sputa. Absence of bacterial growth was observed in 22% and 5% of mucoid and purulent sputa, respectively. Among mucoid sputa, Gram positive bacterial growth occurred more commonly compared to Gram negative and Pseudomonas aeruginosa/Enterobacteriaceae (56%, 24%, 20%, respectively). In purulent sputa, Gram positives were found in 38% of cases, Gram negatives in 38%, and P. aeruginosa/Enterobacteriaceae in 24%. We evaluated whether functional impairment (FEV1) orientates as to the infectious etiology of exacerbations. Significant differences were observed in the distribution of pathogens. Gram negative and P. aeruginosa/Enterobacteriaceae were isolated more frequently in the sputum when FEV1 was <35%. Our study indicates that purulent sputum is strongly associated with bacterial growth in COPD exacerbations. Deepening sputum color (from yellowish to brownish) was associated with increased yield of Gram negative and P. aeruginosa/Enterobacteriaceae.
authors.affiliation: Institute of Respiratory Diseases, University of Milan, IRCCS Ospedale Maggiore Milano, via F. Sforza 35, 20122 Milan, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Allegra
authors.forename: Francesco
authors.initials: F
authors.lastname: Blasi
authors.forename: PierLuigi
authors.initials: P
authors.lastname: Diano
authors.forename: Roberto
authors.initials: R
authors.lastname: Cosentini
authors.forename: Paolo
authors.initials: P
authors.lastname: Tarsia
authors.forename: Marco
authors.initials: M
authors.lastname: Confalonieri
authors.forename: Katerina
authors.initials: K
authors.lastname: Dimakou
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Valenti
mesh_terms: D000208:Acute Disease; D000368:Aged; D001424:Bacterial Infections / Q000150:complications* / Q000503:physiopathology; D001431:Bacteriological Techniques; D003116:Color; D003124:Colorimetry; D004755:Enterobacteriaceae / Q000302:isolation & purification; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D029424:Pulmonary Disease, Chronic Obstructive / Q000382:microbiology* / Q000503:physiopathology; D012008:Recurrence; D012129:Respiratory Function Tests; D012680:Sensitivity and Specificity; D013183:Sputum