A systemic treatment with corticosteroids has been advocated for various bacterial infectious diseases. Since the production of CRP is down-regulated by corticosteroids, a smaller increase or a more rapid decrease of this acute phase protein will:

1. suggest attenuated systemic inflammation, but
2. does not necessarily reflect adequate therapy of the infection.

For several reasons (good diagnostic tool for sepsis, induction not decreased by immunosuppressive therapy), procalcitonin could be a better marker for activity of sepsis in patients under corticosteroids. As this issue has not yet been examined the investigators will prospectively study the time-course of PTC and CRP in a well-defined septic patient group, that in adjunction to antibiotic therapy also received systemic corticosteroid treatment and compare it to a similar group without corticosteroid treatment.

Inclusion Criteria:

• Acute exacerbation of chronic obstructive pulmonary disease (COPD) due to bacterial pneumonia

Exclusion Criteria:

• Chronic systemic use of corticosteroids