Value of sputum culture combined with serum PCT, CRP and ESR levels in the diagnosis of lower respiratory tract infection

Abstract

Objective To investigate the application value of sputum culture combined with serum erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and procalcitonin (PCT) levels in the diagnosis of lower respiratory tract infection. Methods Fifty-nine patients with lower respiratory tract infection in hospital were selected as study group, including 27 cases of bacterial infection, 32 cases of non-bacterial infection; and 58 healthy subjects were selected as the control group. Sputum specimens were callected from all patients and were cultured; and serum ESR, CRP, PCT level were detected. The levels of serum ESR, CRP and PCT were compared between the two groups. The levels of ESR, CRP and PCT in serum of patients with bacterial infection and non-bacterial infection were compared. The distribution of pathogens in the study group was statistically analyzed. The sputum cultures, serum levels of ESR, CRP and PCT were detected and the clinical outcome of lower respiratory tract infection was confirmed clinically. The clinical results were used as the gold standard to compare the results of sputum culture, serum ESR, CRP, PCT levels, single detection and combined detection of lower respiratory tract infections. Results The levels of serum ESR, CRP and PCT in the study group were higher than those in the control group, and the differences were significant (P<0.05). The levels of serum ESR, CRP and PCT in patients with bacterial infection were higher than those in patients with non bacterial infections, and the differences were significant (P<0.05). There were 178 pathogens in the study group, including 4 cases of fungi, accounting for 2.25%; 81 cases of gram negative bacteria, accounting for 45.51% and 93 cases of gram positive bacteria, accounting for 52.24%. The sensitivity, specificity and accuracy of sputum culture, serum ESR, CRP and PCT levels were lower than those of single detection, and the differences were significant (P<0.05). Conclusions The serum levels of ESR, CRP and PCT are higher in patients with lower respiratory tract infection, and the detection of serum ESR, CRP and PCT is helpful to identify the types of infection. Sputum culture combined with serum ESR, CRP and PCT levels in the diagnosis of lower respiratory tract infection can significantly improve the sensitivity, specificity and accuracy of the diagnosis, and the application value is higher. Key words: Sputum culture; Erythrocyte sedimentation rate; C reactive protein; Procalcitonin; Lower respiratory tract infection