Analysis Of Etiology And Prognostic Factors Of Severe Community Acquired Pneumonia In Adults

Objective:Community acquired pneumonia(CAP)is one of the most common respiratory diseases,and the prognosis of most CAP patients is good.A small number of patients may develop severe pneumonia due to advanced age or combined with underlying diseases.Severe community-acquired pneumonia(SCAP)has a very high fatality rate if it is not treated in time.Early etiological diagnosis is of great significance for the diagnosis,treatment and prognosis of SCAP.Second-generation sequencing(NGS)is a new method for detection of pathogens in recent years.It has many advantages,such as wide coverage of pathogens,short time consuming and sensitive detection.The purpose of this study was to understand the etiological composition of adult severe community-acquired pneumonia in the First Affiliated Hospital of China Medical University,compare the pathogen physical examination findings between NGS and traditional etiological detection methods,and analyze the related factors affecting the prognosis of patients.Methods:Patients with severe community-acquired pneumonia who were admitted to the emergency department or hospital of the First Affiliated Hospital of China Medical University from October 2018 to January 2021 were collected according to the admission criteria.SCAP was diagnosed according to the diagnostic criteria of the Infectious Diseases Society of America/American Thoracic Society and the Chinese Thoracic Society(IDSA/ATS,CTS2016)for severe community-acquired pneumonia.All patients signed informed consent.Within 24 hours after admission,10 ml of venous blood(including 5ml of isolated serum and 5ml of anticoagulant)were collected,2ml of serum and 5ml of lower respiratory secretions were sent to BGI for NGS detection,and 10 ml of clean midstream urine was collected for Legionella and Streptococcus pneumoniae urinary antigen detection.At the same time,the lower respiratory tract secretion culture,blood culture,serum Legionella,Mycoplasma pneumoniae antibody detection were improved.Some patients were sent to CDC for polymerase chain reaction(PCR).The pathogenic composition of SCAP patients admitted to the First Affiliated Hospital of China Medical University was understood through a variety of etiological detection methods.The prognosis of SCAP patients was evaluated by following up the survival status of the patients after 30 days,and the related factors affecting the prognosis were analyzed.Results:A total of 46 patients with SCAP were included in this study,including 31males(67.39%)with an average age of 57.45±15.44 years,15 females(32.61%)with an average age of 56.40±11.49 years,and 31 patients(67.39%)with two or more basic diseases,of which 20 patients(64.52%)had two or more basic diseases.46 cases were treated by NGS detection combined traditional etiology detection method(blood,phlegm cultivation,serum legionella bacteria,mycoplasma antibodies,etc.),a total of36 patients(78.26%)detected pathogens,11 cases of mixed infection,the bacteria 32cases(56.14%),including 8 cases of klebsiella pneumoniae,staphylococcus aureus in5 cases,4 cases were acinetobacter baumannii,excrement enterococcus in 4 cases,3cases of pneumonia streptococcus,pseudomonas aeruginosa(3 cases),abscess nou bacteria in 1 case,1 case in enterococcus,1 cases of e.coli,eosinophilic malt narrow food in 1 case,sewers e.coli bacterium in 1 case;There were 5 cases(8.77%)of virus,including 4 cases of influenza A H1N1 virus and 1 case of adenovirus.There were 5cases of fungi(8.77%),including 3 cases of Pneumocystis jevi,1 case of Mucor,and1 case of Candida albicans.There were 3 cases(5.26%)of atypical pathogens,all of which were Legionella pneumophila.Mycobacterium tuberculosis was found in 2cases(3.51%).By comparing the detection rate of different etiological detection methods,it was found that the highest detection rate of NGS in lower respiratory tract secretion was 63.04%,followed by culture of lower respiratory tract secretion(28.26%).The cumulative survival curve showed that the survival rate of patients in the detected pathogen group was significantly higher than that in the undetected pathogen group at 1 to 10 days after the diagnosis of SCAP,and was still higher than that in the undetected pathogen group afterwards,but there was no significant difference in the survival rate between the two groups at 30 days(P>0.05).Univariate prognostic analysis indicated that mechanical ventilation,combined with two or more basic diseases,elevated blood urea nitrogen and blood lactic acid,Curb-65 score ≥3were associated with poor prognosis(P<0.05),but multivariate logistic regression showed that only serum lactic acid increased(P<0.05)(95%CI: 0.000-0.886),Curb-65 score ≥3(P<0.05)(95%CI: 0.004-0.959)were associated with poor prognosis.Conclusion: 1.The detection rate of adult SCAP pathogens can reach 78.26% by NGS combined with traditional etiological detection method,and the positive detection rate of NGS in lower respiratory secretions is higher than that in culture of lower respiratory secretions.2.The main pathogens of adult SCAP infection in our hospital were bacteria(56.14%),followed by viruses and fungi(8.77%)and atypical pathogens(5.26%).Mixed infection accounted for 30.56%.3.Curb-65 score ≥3 and elevated blood lactic acid level were independent risk factors for poor prognosis in adult SCAP patients.