Role of C-reactive protein and procalcitonin in differentiation of tuberculosis from bacterial community acquired pneumonia

Abstract

Background/aims: We investigated the utility of serum C-reactive protein (CRP) and procalcitonin (PCT) for differentiating pulmonary tuberculosis (TB) from bacterial community-acquired pneumonia (CAP) in South Korea, a country with an intermediate TB burden.

Methods: We conducted a prospective study, enrolling 87 participants with suspected CAP in a community-based referral hospital. A clinical assessment was performed before treatment, and serum CRP and PCT were measured. The test results were compared to the final diagnoses.

Results: Of the 87 patients, 57 had bacterial CAP and 30 had pulmonary TB. The median CRP concentration was 14.58 mg/dL (range, 0.30 to 36.61) in patients with bacterial CAP and 5.27 mg/dL (range, 0.24 to 13.22) in those with pulmonary TB (p<0.001). The median PCT level was 0.514 ng/mL (range, 0.01 to 27.75) with bacterial CAP and 0.029 ng/mL (range, 0.01 to 0.87) with pulmonary TB (p<0.001). No difference was detected in the discriminative values of CRP and PCT (p=0.733).

Conclusions: The concentrations of CRP and PCT differed significantly in patients with pulmonary TB and bacterial CAP. The high sensitivity and negative predictive value for differentiating pulmonary TB from bacterial CAP suggest a supplementary role of CRP and PCT in the diagnostic exclusion of pulmonary TB from bacterial CAP in areas with an intermediate prevalence of pulmonary TB.

Keywords: C-reactive protein; Pneumonia, community acquired; Procalcitonin; Tuberculosis.

Figure 1

Receiver-operating characteristics curve for discriminating between pulmonary tuberculosis and bacterial community-acquired pneumonia for C-reactive protein (CRP) and procalcitonin (PCT). No difference was detected in the discriminative value between CRP and PCT.

Figure 2

C-reactive protein (CRP) and procalcitonin (PCT) concentration according to the pneumonia severity index in bacterial community-acquired pneumonia. Patients in risk classes III and V had a higher median PCT value compared to those in classes I and II, whereas no significant difference was observed in the CRP concentrations between those groups classified as Pneumonia Severity Index (PSI) I-II or PSI III-V.