Objective:To observe the efficacy and safety of combined lienal polypeptide injection therapy in the treatment of Mycoplasma pneumoniae pneumonia（MPP）in children aged 3 to 14 years old in multiple clinical centers.Methods:A randomized，controlled，multi-center clinical study design was adopted.A total of 240 hospitalized children aged 3 to 14 years old with MPP from 7 hospitals from September 1，2023 to January 31，2024 were included.According to the severity of pneumonia，they were divided into the mild MPP group with 80 cases and the severe MPP/refractory MPP（SMPP/RMPP）group with 160 cases，and then randomly divided into the control group and the experimental group at a ratio of 1 ∶1，using the random number table method.After screening，subjects entered a treatment period of 5 to 7 days.The control group was treated with azithromycin，while the experimental group was treated with azithromycin plus lienal polypeptide injection .The recovery of lung CT，length of hospital stay，duration of fever，cough score，whether mild cases developed into severe or refractory cases，duration of hormone use，use of intravenous immunoglobulin（IVIG），bronchoscopy treatment，and immune function were observed between the two groups to evaluate the efficacy of lienal polypeptide injection.Adverse events after medication，vital signs，blood routine，urine routine，liver function，myocardial enzymes，renal function，and electrocardiogram were observed to evaluate the safety. Results:A total of 231 subjects have completed the trial in the 7 hospitals，including 118 cases in the experimental group and 113 cases in the control group.Main observation index：the rate of lung CT aggravation in the experimental group was lower than that in the control group（2.6% vs 15.3%， P<0.01），and the difference was statistically significant.Secondary indexes：there were no statistically significant differences in the length of hospital stay，duration of fever，cough score，duration of hormone use，whether IVIG treatment was used，the number of bronchoscopy treatment cases，and immunoglobulin between the two groups（all P>0.05）.However，the rate of cases of plastic bronchitis（PB）found under bronchoscopy in the experimental group was lower than that in the control group（0 vs 18.8%， P=0.03），and the difference was statistically significant.Among the mild MPP（72 cases），there were no statistically significant differences in the length of hospital stay，duration of fever，cough score，duration of hormone use，whether IVIG treatment was used，the number of bronchoscopy treatment cases，and the improvement rate of lung CT between the two groups（all P>0.05）.However，compared with the control group，the rate of cases developing into SMPP/RMPP in the experimental group was less（24.3% vs 48.6%， P=0.03），and the difference in IgG before and after treatment was small［0.53（-0.04，1.18）g/L vs 1.33（0.48，2.25）g/L， P=0.01］.Among the SMPP/RMPP cases（159 cases），the rate of cases of PB found under bronchoscopy in the experimental group was less than that in the control group（0 vs 20%， P=0.04），and the rate of cases with aggravated lung CT in the experimental group was less than that in the control group（1.3% vs 19.5%， P<0.01），and the improvement rate of lung CT in the experimental group was higher than that in the control group（88.8% vs 75.3%， P=0.03），with statistically significant differences.There were no statistically significant differences in the length of hospital stay，duration of fever，cough score，duration of hormone use，whether IVIG treatment was used，the number of bronchoscopy treatment cases，and immunoglobulin between the two groups（all P>0.05）.Two cases in the experimental group developed rashes，which improved after the drug was discontinued.There were no serious adverse reactions such as abnormal vital signs like dyspnea and cyanosis due to the use of lienal polypeptide injection.There were no obvious changes in blood routine，liver function，myocardial enzymes，renal function，electrocardiogram，and urine routine values before and after medication compared with the baseline. Conclusion:The combined use of lienal polypeptide injection in the treatment of MPP in children can reduce the probability of the transformation from mild cases to SMPP/RMPP，reduce the rate of aggravation of the image findings，promote the absorption of lung inflammation，reduce the rate of PB found under bronchoscopy，and has good safety.

Objective:To explore the clinical characteristics of Mycoplasma pneumoniae (MP) bronchiolitis to provide references for clinical prevention and treatment.Methods:From January 2019 to January 2020, the clinical data of children diagnosed with MP bronchiolitis in the Department of Respiratory 2 of Hebei Children′s Hospital were retrospectively collected and analyzed, and the patients were followed up to observe the prognosis.Results:Among the 67 children, there were 39 boys and 28 girls, with age of 5 (1-14) years.All the children had cough, 63 cases (94.0%) had fever, 49 cases (77.8%) had high fever (≥39.0 ℃), and the median total fever course was 8(1-27) d; 10 cases (14.9%) had wheezing; 5 cases (7.5%) had dyspnea; 3 cases (4.5%) had hypoxemia; wet rales were heard in 58 cases (86.6%) and wheezing in 10 cases (14.9%). Forty-eight patients (71.6%) had family allergy history or personal allergy history.The average value of peripheral blood white blood cells was (8.6±2.6)×10 9/L; the me-dian of C reactive protein was 9.1(0.5-55.6) mg/L, of which 7 cases (10.4%) were ≥30 mg/L; the median of lactate dehydrogenase was 278(181-590) U/L.Tree bud sign and central lobular nodules were the main findings of high-resolution CT of the chest.Among them, 45 cases (67.2%) had bilateral lesions, 38 cases (56.7%) involved ≥3 lung lobes, and 22 cases (32.8%) had a little lung consolidation, 19 cases (28.4%) had a small amount of pleural effusion.The bronchoscopic features of 35 children (52.2%): 71.4%(25/35 cases) showed white flocculent and cord-like secretions, 17.1%(6/35 cases) displayed mucus plugs blocking the lumen, and 10.9%(4/35 cases) showed no-dular protrusions and granulation tissue hyperplasia.All children were treated with Azithromycin sequentially; 42 children (62.7%) were treated with low-dose hormones, and the average initiation time was on day (10.62±2.71) and the median course was 14(2-42) d. Sixty-seven cases were followed up for half a year, of which 61 cases (91.0%) had almost complete lung recovery, and 6 cases (9.0%) developed bronchiolitis obliterans (BO). Conclusions:MP bronchiolitis mostly occurs in infants and preschool children with a family history of allergies or personal allergies.Fever and cough are the main clinical manifestations.In severe cases, dyspnea and hypoxemia may occur.The physical signs of the lungs are mainly include wet rales, some of which are wheezing.White flocculent and cord-like secretions are the main manifestations of bronchoscopy.After active treatment, most children have a good prognosis, and some children may develop BO.

Objectives To analyze the clinical characteristics, treatment and prognosis of necrotizing pneumonia caused by Mycoplasma pneumoniae (MP) infection in children. Method The clinical data of children with necrotizing pneumonia cause by MP infection from October 2016 to October 2017 were retrospectively analyzed. Results A total of 26 children (10 males and 16 females) with an average age of (5.76±2.60) years, were enrolled in the study. All children were characterized by fever and cough. High fever ( ≥ 39.0 ℃) was seen in 23 cases (88.5％) and the total duration of fever was (16.88±7.42) days. Pulmonary auscultation showed a reduction in respiratory sounds in all children. The range of peripheral blood leukocytes were (9.0～36.8) ×109/L, mean peak neutrophil ratio was (69.2±13.2) ％, and the range of C-reactive protein (CRP) was (1～202.5) mg/L. The mean value of lactic dehydrogenase (LDH) was (448±247) U/L. At the beginning of the disease, the chest images showed homogeneous solid high-density images over the whole lung lobe and 20 cases (76.9％) were complicated with pleural effusion. At the later stage, lung CT showed thin-walled cavities or multiple air-containing cysts on the basis of lung consolidation. Fiberoptic bronchoscopy showed lumen obstruction caused by mucus plugs in 23 cases (88.5％) . All the children were treated with methylprednisolone. The dose of 2 mg/ (kg·d) was effective in 21 cases and the fever was relieved in 5 cases after the dose was adjusted to 4 mg/ (kg·d) , and the average hormone application time was (13.08 ± 8.38) d. The median length of hospital stay was [16.5 (7～32) ] d. Two cases were lost to follow-up and 24 cases finished 6-month follow-up. Lung CT showed almost complete recovery of the lungs in 16 cases, residual pleural hypertrophy in 5 cases, and bronchiectasis in 1 case and bronchiolitis obliterans in 2 cases. Conclusion Necrotic pneumonia in children caused by MP infection is characterized by persistent high fever, decreased respiratory sounds, lung consolidation and mucus plugs induced lumen obstruction. The prognosis is relatively good after active anti-infection and hormone therapy.

Objective To explore the clinical application of FP-PCR method to detect MP-DNA.Methods Five hundred and sixty-three children suspected of MP infection were enrolled in experimental group. FP-PCR was adopted to detect MP-DNA. MP-DNA was re-detected later in 60 children. At the same time,MP-Ab (MP antibody) was detected by means of particle agglutination. MP-Ab was re-detected one or two weeks later. Also 20 healthy children were selected as the control group. Results The positive rate of MP-DNA and MP-Ab were 34. 99% and 35.52% respectively,which showed no significant difference (x2 =0. 31, P > 0. 05). The coincidence of the two methods was 97. 69%. But the positive rate of MP-DNA was significantly higher than that of MP-Ab in the early stage(30. 48% vs 10. 16%) (x2 = 74. 46, P < 0. 05).The sensitivity and specificity of FP-PCR were 96. 00% and 98.62% respectively. The result of reviewed MP-DNA was consistent with the clinical diagnosis. Conclusion FP-PCR method is very sensitive, convenient and stable. It is fit for the clinical application ,especially the diagnosis of early MP infection. It helps to identify those who had been infected with MP before.