To Investigate The Value Of BALF Metagenomic Sequencing In The Diagnosis And Treatment Of Severe Pneumonia In Adults

Background With the increasing diversity and complexity of the spectrum of respiratory diseases,the incidence of severe pneumonia is on the rise,the mortality and disability rates remain high.Early precision etiological diagnosis is beneficial for targeted anti-infective therapy,which significantly improves the prognosis,and has become the focus of current research.Objective By comparing the application of metagenomic sequencing of bronchoalveolar lavage fluid with conventional etiological detection in the diagnosis and treatment of severe pneumonia in adults,to determine whether mNGS of bronchoalveolar lavage fluid has significant advantages compared with conventional detection in patients with severe pneumonia and improves the diagnosis and treatment level of severe pneumonia.Methods A total of 155 patients with severe pneumonia admitted to the RICU of our hospital from August 2019 to October 2021 were prospective analyzed,and divided into NGS group(85 cases)and the control group(70 cases)according to whether they agreed to mNGS examination or not.Patients in both groups completed conventional etiological testing,the NGS group completed the BALF metagenomic sequencing and adjusted the anti-infective treatment strategy according to the sequencing results.The control group adjusted the treatment according to the conventional etiological results.The basic information,conventional and mNGS etiological results,APACHE II score and SOFA score,and organ function support(vasoactive drugs,invasive ventilator,and CRRT utilization rate and time),anti-infection adjustment,discharge,and 28-day and 90-day outcomes were analyzed from the two groups of patients.Results(1)There was no significant difference in gender,age,basic disease composition,APACHE Ⅱ score and SOFA score before treatment between the two groups.The discharge mortality(23.53% vs 41.43%,P=0.02),28 day all-cause mortality(28.24% vs 46.27%,P=0.02)and 90 day all-cause mortality(29.41% vs 50.75%,P<0.01)in NGS group were significantly lower than those in control group.(2)All 85 patients in the NGS group completed BALF mNGS and conventional pathogenic testing,and 77 patients were positive and 8 were negative by mNGS,49 patients were positive and 36 were negative by conventional pathogenic testing,and 3patients were negative by both methods.The positive rate of mNGS was significantly higher than that of conventional pathogen detection(90.59% vs 57.65%,P<0.01).(3)Pathogen composition: A total of 126 pathogens were identified from 85 patients by mNGS and 65 were detected by conventional etiology,and the distribution of pathogens was gram-positive(20.63% vs 6.15%),gram-negative(26.98% vs 35.38%),fungus(27.78% vs 24.62%),viral(11.90% vs 21.54%),atypical(5.56% vs 4.62%),my cobacterial(7.14% vs 7.69%),mNGS detected more Streptococcus pneumoniae,Pneumocystis jiroveci,Aspergillus spp,and Chlamydia psittaci than conventional etiology.mNGS diagnosed simple infection in 61.18% and mixed infection in 29.41%;conventional detection was 50.59% and 7.06% respectively.There was a statistically significant difference between mNGS and conventional detection in identification of mixed infection(P<0.05).(4)Etiology matching: The complete coincidence rate between mNGS detection and conventional etiology detection was 28.24%(24/85),the partial coincidence rate was 11.76%(10/85),and the complete inconsistency rate was 60.00%(51/85).(5)Adjustment of anti-infective treatment strategies: 52 patients in the NGS group adjusted their anti-infective protocol according to the sequencing results,and 33 patients did not.Among them,21 patients with negative conventional tests adjusted their treatment according to the mNGS results,18 patients improved,and 3 died.In the control group,30 patients adjusted their anti-infection protocol according to conventional testing,and 40 patients were not adjusted.The effective guidance rate between mNGS and conventional etiology(76.47% vs 58.57%,P=0.02)was significantly different.(6)One week after adjusting the anti-infection strategy according to etiology,the APACHE Ⅱ score(10 vs 17.5,P<0.01)and SOFA score(2 vs 5,P<0.01)of patients in NGS group were significantly lower than those in the control group.The average time in ICU(6 vs 9 days,P=0.02),the utilization rate of mechanical ventilation(57.6% vs82.9%,P<0.01)and the time(P<0.01),the utilization rate of vasoactive dru-gs(32.9%vs 62.9%,P<0.01)and time(P<0.01)in NGS group were significantly lower than those in the control group.There was no significant difference in total hos-pital time(16 vs 16.5 days,P=0.64),total cost(4.89 vs 6.18 Ten thousand yuan,P=0.17),CRRT utilization rate(10.71% vs 20.00%,P=0.11)andtime(P=0.10)between the two groups.Conclusion(1)BALF mNGS has a higher positive rate and sensitivity than conventional pathogenic;especially,it has a unique advantage over other pathogens that are difficult to identify by conventional etiology,such as Chlamydia psittaci,Legionella pneumophila,Pneumocystis jiroveci,and nontuberculous mycobacteria,and facilitates the recognition of mixed infections.(2)BALF mNGS facilitates the early identification of pathogens and guides targeted anti-infective therapy,reduces unnecessary broad-spectrum antimicrobialuse,and promotes rational management of the clinical use of antimicrobials.(3)BALF mNGS guided therapy is beneficial to reduce the incidence of organ failure,reduce the length of ICU time,reduce mortality,and improve survival and significantly improve outcomes in patients with severe pneumonia.