Chronic bronchial infection in COPD. Is there an infective phenotype?

Abstract

Microorganisms, particularly bacteria, are frequently found in the lower airways of COPD patients, both in stable state and during exacerbations. The host-pathogen relationship in COPD is a complex, dynamic process characterised by frequent changes in pathogens, their strains and loads, and subsequent host immune responses. Exacerbations are detrimental events in the course of COPD and evidence suggests that 70% may be caused by microorganisms. When considering bacterial exacerbations, recent findings based on molecular typing have demonstrated that the acquisition of new strains of bacteria or antigenic changes in pre-existing strains are the most important triggers for exacerbation onset. Even in clinically stable COPD patients the presence of microorganisms in their lower airways may cause harmful effects and induce chronic low-grade airway inflammation leading to increased exacerbation frequency, an accelerated decline in lung function and impaired health-related quality of life. Besides intraluminal localisation in the distal airways, bacteria can be found in the bronchial walls and parenchymal lung tissue of COPD patients. Therefore, the isolation of pathogenic bacteria in stable COPD should be considered as a form of chronic infection rather than colonisation. This new approach may have important implications for the management of patients with COPD.

Pseudomonas aeruginosa triggers CFTR-mediated airway surface liquid secretion in swine trachea

“…These results suggest that the progression of CF airway disease may be ameliorated by treatments that improve the response of the airways to inhaled bacteria, such as prophylactic antibiotic treatment. In addition, abnormal ASL secretion in response to microbes may contribute to other pathological conditions, such as chronic obstructive pulmonary disease and asthma, in which airway remodeling occurs and responses to microbes could be blunted (37).…”

Viral, bacterial or both? Regardless, we need to treat infection in COPD

“…More recently, the presence of bronchiectasis in patients with COPD [11] and the persistent colonisation by unusual microorganisms [12] have also been associated with increased mortality. These findings justify the identification of an ''infective phenotype'' that is usually a frequent exacerbator with mucous hypersecretion producing dark sputum during the stable state that is more abundant during exacerbations, and who requires frequent courses of antibiotics and probably demonstrates cylindrical bronchiectasis on computed tomography [13]. Treatment with bronchodilators and ICS never fully prevents infective exacerbations in this phenotype of patients.…”

Risk factors for meticillin-resistant Staphylococcus aureus colonization in dialysis patients: a meta-analysis

“…All of them are implicated in defective mucus clearance in lower airways, which predisposes to pathogen colonization. 30,31 The efficacy of laboratory methods for MRSA screening can be assessed on the basis of sensitivity, specificity, turnaround time, and simplicity in performance and cost. In our metaanalysis (Table I), most studies used agar culture test which detects resistance by disc diffusion, a process which takes two to five days.…”