Usefulness of procalcitonin to differentiate typical from atypical community-acquired pneumonia

Background. The value of elevated serum procalcitonin concentration for differentiating between typical and atypical community-acquired pneumonia was assessed and compared with other parameters that are usually used in clinical practice. Patients and methods: Thirty consecutive adult patients with community-acquired bacterial pneumonia admitted to the Department of Infectious Diseases, University Medical Center Ljubljana, Slovenia, were included in this prospective study. Only those patients for whom the etiology of bacterial pneumonia was confirmed participated in the study. Results: The median serum procalcitonin level in patients with typical pneumonia was 7.64ng/ml (range 0.26-63.16) and in the group with atypical pneumonia 0.80ng/ml (range 0.13-34.90). A significant difference between the typical and atypical pneumonia groups was found only for the procalcitonin serum concentration on admission. The standard laboratory markers of bacterial infections, such as C-reactive protein, total leukocyte count and immature polymorphonuclear cells, did not discriminate between typical and atypical etiology. Median procalcitonin levels were significantly higher among patients with bacteremic pneumonia. Conclusions: Determination of the procalcitonin level may provide useful additional diagnostic information on the etiology of pneumonia and could have a crucial influence on the initial antimicrobial therapy.