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Pseudomonas aeruginosa in Chronic Obstructive Pulmonary Disease

¹ Department of Medicine and ² Department of Microbiology and Immunology, State University of New York at Buffalo, Buffalo New York; ³ Veterans Affairs Western New York Healthcare System, Buffalo, New York; and ⁴ Department of Biostatistics, State University of New York at Buffalo, Buffalo, New York

Correspondence and requests for reprints should be addressed to Timothy F. Murphy, M.D., Medical Research 151, Buffalo Veterans Affairs Medical Center, 3495 Bailey Avenue, Buffalo, NY 14215. E-mail: murphyt{at}buffalo.edu

Rationale: Pseudomonas aeruginosa is isolated from adults with chronic obstructive pulmonary disease (COPD) in cross-sectional studies. However, patterns of carriage and the role of P. aeruginosa in COPD are unknown.

Objectives: To elucidate carriage patterns, phenotypes of strains, clinical manifestations, and the antibody response to P. aeruginosa in COPD.

Methods: A prospective study of adults with COPD was conducted. Isolates of P. aeruginosa were subjected to genotypic and phenotypic analysis. Sputum samples were studied for P. aeruginosa DNA, and immune responses were assayed.

Measurements and Main Results: We analyzed longitudinal clinical data, sputum cultures, pulsed-field gel electrophoresis of bacterial DNA, polymerase chain reaction of sputum, and immunoblot assays of serum. Fifty-seven episodes of acquisition of strains of P. aeruginosa were observed in 39 of 126 patients over 10 years. Acquisition of a new strain was associated with exacerbation. Thirty-one episodes of carriage were followed by clearance of the strain; 16 were of short (<1 mo) duration. Thirteen strains demonstrated persistence, and 13 strains were of indeterminate duration. Six strains were mucoid and were more likely to persist than nonmucoid strains (P = 0.005). Antibody responses developed in 53.8% of persistent carriage and in only 9.7% of short-term carriage episodes (P = 0.003). Antibiotics did not account for clearance.

Conclusions: Two distinct patterns of carriage by P. aeruginosa were observed: (1) short-term colonization followed by clearance and (2) long-term persistence. Mucoid strains showed persistence. Acquisition of P. aeruginosa is associated with the occurrence of an exacerbation. Serum antibody responses do not mediate clearance of P. aeruginosa.

Key Words: respiratory tract infection • exacerbation • immune response • sputum • polymerase chain reaction

AT A GLANCE COMMENTARY Scientific Knowledge on the Subject Pseudomonas aeruginosa is isolated from the sputum in chronic obstructive pulmonary disease, but carriage patterns, clinical manifestations, and immune responses have not been studied prospectively. What This Study Adds to the Field This study shows that (1) there are distinct patterns of carriage of P. aeruginosa in chronic obstructive pulmonary disease, (2) mucoid strains are uncommon but persistent, (3) acquisition of a new strain is associated with exacerbation, and (4) antibody responses are a marker for colonization.