[Comparative analysis of clinical characteristics and prognosis between bacterial necrotizing pneumonia and Mycoplasma pneumoniae necrotizing pneumonia in children]

Objective: To compare the characteristics of Mycoplasma pneumoniae necrotizing pneumonia (MPNP) and bacterial necrotizing pneumonia (BNP), and explore the biomarkers for differentiation of MPNP from BNP. Methods: A retrospective, observational study of 52 necrotizing pneumonia (NP) cases who were hospitalized in our hospital from January 2008 to December 2017 was conducted. According to the pathogen causing NP, patients were divided into two groups, BNP and MPNP, and the clinical manifestations, laboratory data, imaging findings, hospital course and prognosis between these groups were analyzed. Results: This study enrolled 19 boys and 33 girls, and the median ages of patients were 4.4 (0.1-13.8) years old. Of the totally of 52 NP patients, 19 were in the BNP group (9 boys and 10 girls), 33 were in the MPNP group (10 boys and 23 girls). The mean age of MPNP patients was much older than that of BNP patients (5.2 (2.3-13.2) years vs. 1.8 (0.1-13.8) years, Z=-0.128, P<0.01). The number of patients with tachypnea and pleural effusion septation were significantly higher in BNP patients than those in MPNP patients (15 cases vs. 4 cases, χ(2)=23.222, P<0.01; 14 cases vs. 1 case, χ(2)=29.326, P<0.01), which more needed to oxygentherapy (18 cases vs. 12 cases, χ(2)=16.833, P<0.01) and undergo chest drainage (9 cases vs. 4 cases, χ(2)=5.829, P=0.022); while the number of patients required bronchoalveolar lavage was higher in MPNP patients than that in BNP patients (5 cases vs. 32 cases, χ(2)=29.326, P<0.01). The values of white blood cell (WBC) (23.2 (5.2-67.1)×10(9)/L vs. 9.7 (6.3-18.7)×10(9)/L, Z=-4.855, P<0.01), procalcitonin (PCT) (3.69 (0.23-90.15) mg/L vs. 0.28 (0.02-1.44) mg/L, Z=-3.207, P=0.001), C reactive protein (CRP) (160 (94-220) mg/L vs. 90 (5-134) mg/L, Z=-4.337, P<0.01), interleukin (IL)-10 (11.7 (4.2-401.5) ng/L vs. 4.8 (2.0-23.4) ng/L, Z=-2.278, P=0.023), pleural fluid cell count (5 200 (120-50 000)×10(6)/L vs. 790 (68-6 920)×10(6)/L, Z=-3.125, P=0.002), pleural fluid lactic dehydrogenase (LDH) (3 990 (589-29 382) U/L vs. 2 211 (673-3 993) U/L, Z=-2.488, P=0.013) in BNP group were significantly higher than those in MPNP group; while the values of pleural fluid glucose(0.43 (0.03-18.00) mmol/L vs. 5.95 (4.27-7.87) mmol/L, Z=-2.795, P=0.005), serum tumor necrosis factor (TNF)-α (2.3 (1.0-2.8) ng/L vs. 2.6 (1.3-109.2) ng/L, Z=-2.113, P=0.035) and interferon (IFN)-γ (4.8 (2.6-7.7) ng/L vs. 11.9 (2.9-154.6) ng/L, Z=-2.455, P=0.014) were lower in BNP group than those in MPNP group. Meanwhile, the mean time from the onset of symptoms to the discovery of necrotic lesions was longer in MPNP group than that in BNP group ((20.6±6.4) days vs. (14.6±6.2) days, t=3.029, P=0.004). After treatments, all patients were discharged without death, WBC and PCT recovered more quickly in MPNP group than those in BNP group (12 (0-24) days vs. 0 (0-23) days, Z=-4.484, P<0.01; 10 (5-15) days vs. 0 (0-23) days, Z=-3.244, P=0.001). As to prognosis, 34 cases were followed up, and the results showed that patients recovered without surgical intervention, and chest lesions were resolved within 3.0 (1.0-8.0) months, and the time to necrosis disappearance was similar in the BNP group and MPNP greup (3.0 (1.0-8.0) months vs. 3.0 (1.0-8.0) months, Z=-0.128, P=0.001). In receiver operator characteristic curve analysis, the cut-off values for the age, WBC, CRP, PCT, pleural fluid cell count and pleural fluid glucose were set at 2.4 years of age, 17.2×10(9)/L, 157 mg/L, 1.505 mg/L, 2 630×10(6)/L and 3.73 mmol/L, respectively. Conclusions: NP is found to be severe and prolonged, yet, reversible through proper therapy, such as rational antibiotics application. The age, WBC, CRP, PCT, pleural fluid cell count and pleural fluid glucose could be used as biomarkers to differentiate MPNP from BNP in children.