The Clinical Application Of Next-generation Sequencing In The Differential Diagnosis Of Pulmonary Infectious Diseases

Objective: Use clinical typical cases to analyze the gains,losses and experience of Next-generation sequencing(NGS)in the differential diagnosis of lung infection/non-infectious lesions with exudative changes in lung imaging.Use NGS results scientifically and objectively,reduce clinical misjudgments caused by NGS results,adjust treatment plans in time,and provide a basis for clinical research.Methods: A retrospective analysis of the clinical data of 24 patients with "pulmonary infection" admitted to the Department of Respiratory and Critical Care,Changzhou Second People’s Hospital from August 2018 to August 2019.All patients underwent bronchoscopic alveolar lavage and sent the alveolar lavage fluid for NGS examination.Routine microbiological testing includes sputum smear and culture.In this study,This article selects 4 typical cases for detailed analysis,including general conditions,clinical manifestations,laboratory examination results,imaging examination results,lung biopsy results and treatment plans,and compare the clinical treatment plan before and after NGS and the patient’s prognosis,analyze the clinical misunderstanding of the differential diagnosis of lung infection/non-infectious lesions with exudative changes in lung imaging with NGS,and provide research for the objective use of NGS results in clinical sciences basis.Results: A total of 24 patients with "pulmonary infection" were included in the study.Among them,17 patients had underlying diseases,1 patient had immunodeficiency,10 patients were positive by routine methods(including smear and Culture),3 patients were pathologically diagnosed as lung cancer,and 23 patients were positive for NGS in bronchoalveolar lavage fluid(23/24).Four of them(p15,P20,p21,P22)were diagnosed as "pulmonary infection",which were admitted to the hospital and received empirical anti-infection treatment,and the clinical symptoms of the patients showed no significant improvement.Improve the routine pathogen detection methods(such as sputum culture,smear),and adjust the anti-infective treatment plan based on the test results.The patient’s symptoms have not improved.Four patients were further tested for pathogens by NGS,and the results respectively suggested that case 1 was mycobacterium tuberculosis infection,case 2 was mainly adenovirus infection,case 3was streptococcal infection,and case 4 was a variety of bacterial infections.According to the NGS results,the patient with Mycobacterium tuberculosis infection in Case 1 was transferred to a specialist hospital for further anti-tuberculosis treatment.During follow-up,the patient’s symptoms improved,the treatment effect was clear,and the lesion was absorbed.Case 2 The adenovirus infection patient continued to strengthen anti-infection and symptomatic and supportive treatment based on the test results and combined with the patient’s condition.The symptoms improved significantly,the treatment effect was clear,and the lesions disappeared significantly.Cases 3 and 4adjusted the anti-infective treatment regimen based on the NGS results,but their symptoms did not improve significantly.A lung biopsy was performed.The results suggested that case 3 was organizing pneumonia and case 4 was lung adenocarcinoma.Case 3 The patient with organizing pneumonia was treated with prednisone,and the symptoms were significantly relieved.Follow-up follow-up showed that the patient had a better prognosis and the lesion was absorbed earlier.According to the results of lung biopsy and lung adenocarcinoma gene sequencing,the patient with lung adenocarcinoma in case 4 adjusted the treatment plan and received multiple chemotherapy.The patient’s clinical symptoms did not improve significantly.The patient’s prognosis was poor and the lesion did not improve significantly.Conclusion: Big data analysis of NGS detection has a very important position in the pathogenic analysis of lung infectious diseases.Through NGS analysis,relatively clear pathogens of infection can usually be obtained to guide clinical treatment;But if NGS analysis results are used blindly and mechanically,sometimes,there will be mislead clinical judgments and affect clinical treatment.According to the clinical data collected in this study,it is verified that NGS,as a detection tool,can detect pathogens that cannot be detected by routine examinations,and is an indispensable detection method for clinical diagnosis.However,in actual clinical applications,scientific dialectics and individualized analysis should be combined with the characteristics of clinical cases.In real clinical events,the lesions characterized by lung consolidation/pulmonary exudative changes are not necessarily lung infections,such as organizing pneumonia and pneumonia-type lung cancer,although they are manifested as "pulmonary infection" The results of disease and NGS also suggest that there may be infections such as bacteria and fungi,but the actual cause of the disease is not the cause of this disease.It may be colonizing bacteria in the lungs or data errors.In short,only scientifically rationalized analysis of NGS test data can provide clinicians with new ideas when diagnosing lung infections/non-infectious diseases,clarify the cause as soon as possible,and further develop reasonable treatment plans.At the same time,other tests such as lung biopsy and imaging data should be combined to make a judgment on the disease,so as to grasp the opportunity for treatment.