Application Value Of Bronchoalveolar Lavage Fluid Targeted Next-generation Sequencing In The Diagnosis And Treatment Of Community-acquired Pneumonia In Children

Objective:To explore the application value of bronchoalveolar lavage fluid targeted next-generation sequencing(tNGS)in the diagnosis and treatment of community-acquired pneumonia in children.Methods:A retrospective analysis was performed on 192 children with community-acquired pneumonia who were admitted to the Children’s Respiratory Department of Jiujiang Maternal and Child Health Hospital from October 2021 to December 2022,who were treated with bronchoalveolar lavage and sent for targeted next-generation sequencing detection.After admission,the children was given empirical anti-infection and symptomatic treatment.Blood routine、Erythrocyte sedimentation rate(ESR)、Procalcitonin(PCT)、D dimer、respiratory etiology,pulmonary imaging and other tests were improved.After the consent of the family members,bronchoalveolar lavage was completed.Two pieces of bronchoalveolar lavage fluid were collected,one for routine bacterial culture and the other for tNGS test.Relevant clinical data were collected,including sex,age,length of stay,clinical diagnosis,inflammatory indicators(leukocytes,neutrophils,C-reactive protein(CRP),PCT,ESR),traditional etiological test results,tNGS results,imaging examination,treatment and outcome,etc.The detection rate,pathogen distribution and consistency of the two detection techniques were compared,the correlation between the sequence number of Mycoplasma pneumoniae detected by tNGS and the clinical manifestations and inflammatory indicators of the disease was also observed.Results:1.A total of 192 children were enrolled in this study,including 108 male children(56.25%)and 84 female children(43.75%),aged 1 year 1 month to 16 years,with an average of 7 years.63 cases(32.81%)were severe pneumonia,129 cases(67.19%)were non-severe pneumonia.95 cases(49.48%)were single infection and97 cases(50.52%)were mixed infection.There was no significant difference between severe and mild infection,single infection and mixed infection(χ~2=1.998,P=0.157;χ~2=1.000,P=0.317).2.tNGS detection technology:Pathogenic microorganisms were detected in all192 cases,the detection rate was 100%.Bacteria were detected in 116 cases(60.42%),viruses in 102 cases(53.13%),mycoplasma pneumoniae in 183 cases(95.31%)and fungi in 11 cases(5.73%).The top three bacterial infections were Streptococcus pneumoniae in 63 cases(32.81%),Haemophilus influenzae in 22 cases(11.46%)and Staphylococcus aureus in 10 cases(5.21%).The top three viral infections were Adenovirus group B 28 cases(14.58%),Rhinovirus type A 14 cases(7.29%)and Human herpesvirus type 4 11 cases(5.73%).Mycoplasma pneumoniae combined with bacterial infection was the most mixed infection in 35 cases(18.23%),followed by Mycoplasma pneumoniae combined with bacterial and viral infection in 24 cases(12.5%)and mycoplasma pneumoniae combined with viral infection in 22 cases(11.46%).3.Traditional pathogen detection technology:Pathogenic microorganisms were detected in 157 cases,the detection rate was 81.77%.Bacteria were detected in 1 case(0.52%),viruses in 4 cases(2.08%),Mycoplasma pneumoniae in 156 cases(81.25%)and Chlamydia pneumoniae in 11 cases(5.73%).Mycoplasma pneumoniae combined with Chlamydia pneumoniae infection was the most mixed infection in 10 cases(5.21%),followed by Mycoplasma pneumoniae combined with virus infection in 2cases(1.04%).4.The detection rates of bacteria,viruses,Mycoplasma pneumoniae and fungi by tNGS were significantly higher than that by traditional pathogen detection(P<0.001).In this study,the tNGS technique did not detect Chlamydia pneumoniae,while the traditional serological test showed positive antibody to Chlamydia pneumoniae,and the difference was statistically significant(χ~2=11.324,P=0.001).5.In the mild disease group,129 cases were detected by tNGS technique,with63 cases(48.84%)of single infection and 66 cases(34.38%)of mixed infection.63cases were detected in the severe group,including 32 cases(16.67%)of single infection and 31 cases(16.65%)of mixed infection.In the mild disease group,102cases were detected by traditional pathogen detection methods,including 99 cases(51.56%)of single infection and 3 cases(1.56%)of mixed infection.58 cases were detected in the severe group,including 49 cases(25.52%)of single infection and 9cases(4.69%)of mixed infection.The detection rate of mixed infection by tNGS detection technology in mild and severe patients was significantly higher than that of traditional methods,and the difference was statistically significant(P<0.001).6.Combined with the clinical practice of the children,the test results of the two methods were compared,and the consistency rate of tNGS detection technology and traditional etiological detection was weak(Kappa=0.000,P=0.997).7.To analyze the relationship between the sequence number of Mycoplasma pneumoniae detected by tNGS technology and the length of hospitalization days,fever days,hormone use time,leukocytes,neutrophils,CRP,D dimer,erythrocyte ESR,and PCT,to determine whether there is a correlation.Spearman correlation analysis showed that the sequence number of Mycoplasma pneumoniae was only negatively correlated with leukocytes.The difference was statistically significant(rs=-0.155,P<0.05),and there was no correlation with the above other indicators(P>0.05).Conclusions:1.tNGS technology can improve the detection rate of pathogens such as bacteria,viruses,Mycoplasma pneumoniae and fungi.2.The detection rate of tNGS was higher than that of traditional etiological detection,especially for mixed infection..3.The sequence number of Mycoplasma pneumoniae had no significant correlation with the clinical manifestations and inflammatory indicators of the disease.4.tNGS technology provides the etiological basis for community-acquired pneumonia in children and guides clinical diagnosis and treatment.