Bacteriological and biochemical criteria for the diagnosis of bacterial infections in chronic obstructive pulmonary disease (COPD).

In a prospective study the quantitated culture of washed sputum, the number of leukocytes and the concentration of albumin and fibrinogen in sputum were compared as diagnostic parameters for bacterial infections in patients with chronic obstructive pulmonary disease. No single criterium and no combination of criteria showed satisfactory specificity and sensitivity. Two reasons were established for the relatively loose correlation between the parameters: 1) they follow a different time course and 2) the biochemical and cellular signs of inflammation have a certain non-specificity with regard to bacterial infections. They also depend on the underlying disease. The selection of optimal criteria will become feasible only after the dynamics of bacterial and other inflammations of the respiratory tract have been studied in detail.