Pathogen Distribution And Clinical Characteristics Of Severe Pneumonia In Immunosuppressed Patients

Objective:To analyze the distribution of pathogens and clinical features of severe pneumonia in immunosuppressed patients,so as to provide evidence for early diagnosis and treatment.Methods:The clinical data of immunosuppressed patients with severe pneumonia admitted to the Respiratory Intensive Care Unit(RICU)of the First Affiliated Hospital of Xinjiang Medical University from July 2015 to January 2023 were retrospectively analyzed.According to the results of pathogen detection,they were divided into bacterial infections.group and non-bacterial infection group.If two or more pathogens are detected in a patient at the same time,the main responsible pathogen will be used as the basis for grouping.The distribution of pathogens was described by percentage(%),the correlation between pathogens and underlying diseases was analyzed,the clinical characteristics of the two groups were analyzed by univariate analysis,and variables with statistical significance were included in multivariate Logistic regression analysis.Results:A total of 205 patients were included in the study,including 116 cases(56.6%)in the bacterial infection group and 89 cases(43.4%)in the non-bacterial infection group.(1)Comparison of baseline data between the two groups:The acute physiology and chronic health status(APACHEⅡ)score of the bacterial infection group was higher[score:15.00(12.00,20.00)vs 13.00(10.00,17.00),X~2=-2.923,P<0.05],suggesting that the bacterial infection group was seriously ill.(2)Distribution of pathogens:A total of 370 strains of pathogens were detected,of which 211 strains(57.0%)were detected in the bacterial infection group,and the top three were 60 strains(16.2%)of Klebsiella pneumoniae and33 strains(8.9%)of Staphylococcus aureus.and 29 strains(7.8%)of Pseudomonas aeruginosa;126 strains(34.1%)of fungi were detected in the non-bacterial infection group,including 70 strains of yeast(18.9%),41 strains of mold(11.1%),and 15 strains of biphasic fungi 16 strains(4.3%)were detected,including 7 strains of cytomegalovirus(1.9%),5 strains of herpes simplex virus(1.3%),3 strains of new coronavirus(0.8%)and1 strain of influenza virus strains(0.3%);13 strains(3.5%)of Mycobacterium tuberculosis and 4 strains(1.1%)of atypical pathogens were detected.(3)Correlation analysis:the incidence of bacterial infection in solid malignant tumors and/or receiving chemotherapy and radiotherapy was significantly increased(P<0.05),while the incidence of non-bacterial infection in long-term use of glucocorticoids and immunosuppressants was significantly increased(P<0.05).(4)Analysis of clinical features and inflammatory markers:Procalcitonin(PCT)[(ng/l):0.58(0.18,1.91)vs 0.33(0.11,1.13),Z=-2.205,P<0.05]and Interleukin-6(IL-6)[(pg/ml):62.85(24.66,366.45)vs 53.30(16.22,116.60),Z=-2.236,P<0.05]in the bacterial infection group were significantly increased.;The chest CT showed bronchial pneumonia and lung consolidation[56.9%(66/116)vs 41.6%(37/89)]significantly more than the non-bacterial infection group,while interstitial pneumonia[41.4%(48/116)vs 58.4%(52/89)]was significantly lower than the bacterial infection group,(P<0.05),percentage of septic shock[26.7%(31/116)vs 9.0%(8/89),X~2=10.283,P<0.05],percentage of nosocomial infection[77.6%(90/116)vs 62.9%(56/89),X~2=5.284,P<0.05]significantly increased in the bacterial infection group,but the bacterial infection group CD4~+T lymphocyte count[(unit/mm3):154.60(75.84,263.85)vs 182.97(106.58,358.54),Z=-2.241,P<0.05]significantly reduced.The results of multivariate Logistic regression analysis showed that septic shock[95%confidence interval(95%CI)=2.698-21.785,X~2=14.611,P<0.001],nosocomial infection[95%confidence interval(95%CI)=2.053-10.665,X~2=13.472,P<0.001]is an independent predictor of higher incidence of bacterial infection group.(5)Respiratory support and hospitalization indicators:The percentage of endotracheal intubation mechanical ventilation(ETI-MV)[75.0%(87/116)vs 61.8%(55/89),X~2=4.124,P<0.05]in the bacterial infection group was significantly higher.Conclusions:(1)The bacterial infection of severe pneumonia in immunosuppressed patients was more than that of other pathogens.Other pathogen infections are more common in fungal infections.(2)Common pathogens of different underlying diseases are different.(3)The chest CT of bacterial infection group mainly showed bronchial pneumonia and pulmonary consolidation,while interstitial pneumonia was more common in non-bacterial infection.The inflammatory indexes of bacterial infection were significantly increased,while the lymphocyte count and CD4~+T lymphocyte count were significantly decreased.(4)The percentage of patients with bacterial infection receiving ETI-MV support was significantly increased.