Procalcitonin and C-reactive protein levels in community-acquired pneumonia: Correlation with etiology and prognosis

Background: The diagnostic value of admission serum levels of procalcitonin (PCT) and C-reactive protein (CRP) as indicators of the etiology and progn osis was prospectively investigated. Patients: 96 patients, 50-85 years of age, treated in the hospital for comm unity-acquired pneumonia (CAP), Results: On admission, all patients had elevated CRP levels (> 10 mg/l), bu t only 60 patients (54%) had elevated PCT levels (> 0.1 mu g/l). The severi ty of disease measured by APACHE II score was strongly associated with admi ssion levels of PCT (p = 0.006), but not with CRP. Eight of nine patients w ith pneumonia caused by atypical agents had PCT levels < 0.5 mu g/l compare d with 6/27 patients with pneumonia caused by classic bacterial pathogens, mainly Streptococcus pneumoniae (p = 0.03). No such correlation between CRP levels and etiology was found. Conclusion: Our data indicate that in patients admitted to the hospital wit h CAP, measurement of PCT gives information about the severity of the disea se, and may aid the physician to differentiate typical bacterial etiology f rom atypical etiology, and thereby to choose appropriate initial antibiotic treatment.