Acute exacerbations of chronic obstructive pulmonary disease

Abstract number: S19

Torres A.

Exacerbations of chronic obstructive pulmonary disease (COPD) are a frequent clinical problem both in the primary care and in the hospital. The microorganisms that are associated with exacerbations are well recognised and include viruses, Chlamydia and bacteria such as S. pneumoniae, H. influenzae and P. aeruginosa. The severity of the COPD and the exacerbation are associated with different pathogens.

In the primary care setting usually these exacerbations are mild and do not need hospitalisation. The routine care of these patients is to administer antibiotics. According to some investigations a great part of these mild exacerbations would not require antibiotic treatment because they are viral in origin or because they are not infectious. However, in the clinical practice is difficult to distinguish between these two situations.

A recent study from our group in COPD exacerbated patients confirms that the existence of sputum purulence referred by the patient is a sensitive and specific variable associated with positive bacterial cultures in bronchoscopic samples.

We do not know if this information can be extrapolated to ambulatory patients but probably yes.

Of course, there are patients that cannot expectorate and some of them may have a bacterial infection. In these

Cases, perhaps biological markers could help to differentiate between viral and bacterial infections. Procalcitonin (PCT) has been studied in COPD exacerbation and in one randomised trial it has been useful continuing or discontinuing antibiotics without recurrence problems. The limitations of this method are the need of a blood sample and the availability of methods able to detect small amounts of PCT.

In terms of pathogens one of the most controversial issue is the role of Pseudomonas aeruginosa. Some studies in some countries confirm that Pseudomonas aeruginosa is isolated in around 10 to 15% of exacerbations. However, the pathogenic mechanisms of Pseudomonas aeruginosa in COPD exacerbations is unclear but the current recommendations advise to treat these patients with antipseudomonal antibiotics

Risk factors are known from individual studies. The ERS guidelines include among them the following: FEV1 < 30%; prior antibiotic treatment, long-term treatment with steroids and prior colonisation or isolation of P. aeruginosa. When two out of these four variables are present antipseudomonal treatment is recommended.