Abstract:Wearable sensing technology has been widely used in biomedical field because of its non-invasive and portable characteristics， and especially in the monitoring of medical biomarkers. From the conventional rigid structure to flexible patch， wearable sensing technology has been greatly enhanced in terms of sensitivity，specificity， stability and practicality. This paper reviews its application and challenges of laboratory medicine， analyzes its pros and cons in the monitoring of small molecules such as glucose and electrolyte， and looks forward to its future prospects， so as to provide reference for promoting the development of new technologies in laboratory medicine.

Abstract:Chinese society has officially entered the great health era. With the continuous improvement of the health literacy，the public's health awareness has gradually changed from passive health to active health，and people begin to pay more attention to the early intervention for diseases. Biomimetic flexible sensor，as a new equipment derived from the interdisciplinarity of bionic-nano-sensing-information，displays slimmer，portable，well biological safety，excellent electrical performance，and high integration. Biomimetic flexible sensor plays an important role in disease monitoring and early warning，and it has obviously been the focal points for future health services. This paper has summarized the types and functions of biomimetic flexible sensors，and concluded its applications and bottlenecks in the field of active health，hoping that this paper may provide the guidelines for the future research of biomimetic flexible sensor.

Abstract:Nucleic acid is of great importance to disease diagnosis because of its rich genetic information. Traditional nucleic acid detection technology is limited by the limitation of time consuming and large equipment， which seriously restricts its application in large-scale and sudden disease detection. Paper-based microfluidic technology has the advantages of portability and self-actuation， providing the possibility for rapid and accurate detection of nucleic acid molecules after integrating isothermal amplification technology. Based on the design of paper-based microfluidic technology，this review has summarized the research progress of paper-based microfluidic technology in the detection of nucleic acid molecules，and analyzed the interference factors that affect the sensitivity and stability of the detection， providing an important reference for promoting the clinical transformation of paper-based microfluidic technology.

Abstract:Catecholamines are closely related to some neuroendocrine tumors. Therefore，the clinical detection of catecholamines is of great value for the early prediction of these diseases as well as for their later monitoring. There are several methods available for the detection of catecholamines，but there is a lack of standardized clinical assays due to the minimal amount of catecholamines in biological samples，their easy oxidation，and the presence of endogenous interferents. This article provides a brief overview of the current methods for the detection of catecholamines and their advantages and disadvantages，and provides references for the clinical detection of catecholamines.

Abstract:Objective To investigate the predictive value of atherosclerotic index of plasma（AIP）， white blood cells（WBC） count and neutrophil lymphocyte ratio（NLR） to acute coronary syndrome（ACS） and the severity of coronary lesions.Methods Patients with suspected coronary heart disease who first visited the hospital from January 2019 to December 2021 were retrospectively enrolled. All patients were divided into two groups，ACS group（n=288） and non-ACS group（n=93）. The receiver operating characteristic （ROC） curve and multivariate logistic regression were used to analyze the predictive value of AIP， WBC count and NLR in ACS. Spearman rank correlation was used to analyze the correlation between the indexes and Gensini score.Results AIP， WBC count and NLR in ACS group were significantly higher than those in non-ACS group（t/Z=3.623，6.697，-6.165，P<0.001）. Logistic regression analysis showed that AIP，WBC count and NLR were independent risk factors for ACS. After excluding confounding factors， with the increase of each additional unit of AIP，WBC and NLR，the risk of ACS increased by 6.739 times（95%CI=2.829-21.169，P<0.001），0.260 times（95%CI=1.113-1.426，P<0.001），and 0.145 times（95%CI=1.036-1.265，P=0.008）. The area under the curve（AUC） for predicting ACS with AIP，WBC count and NLR was 0.627（95%CI=0.563-0.692，P<0.001），0.696（95%CI=0.638-0.755，P<0.001），and 0.713（95%CI=0.652-0.773，P<0.001），respectively. The larger AUC of 0.756（95%CI=0.700-0.813，P<0.001） was observed when the combination of the three indicators was used to predict ACS. The proportions of complete vascular occlusion，left main coronary artery or multiple vascular branch lesions and Gensini score in high AIP， high WBC and high NLR groups were significantly higher than those in low value groups（all P<0.05）. The three indicators were significantly positively correlated with Gensini score（r=0.188，0.313， 0.332，all P<0.001）.Conclusion AIP，WBC count and NLR are independent risk factors for ACS，and their combination has better predictive value for ACS. Moreover，they are positively correlated with the severity of coronary lesions significantly，which may have potential to be biomarkers for ACS risk prediction and condition evaluation.

Abstract:In the context of the global epidemic， nucleic acid detection under on-site conditions plays a more and more important role in epidemic prevention and control， which makes the development of nucleic acid point-of-care testing（POCT） tools facing unprecedented demand. The application of clustered regularly interspaced palindromic repeats-associated nuclease（CRISPR/Cas） to nucleic acid POCT has been developed rapidly and achieved good results in recent years. In the epidemic control areas，customs and disaster areas and other special sites，combining isothermal amplification techniques with CRISPR and being integrated into small handheld devices，these technologies are easier to use and non-professionals can quickly and accurately detect the nucleic acid source of infection. This review first briefly introduces the CRISPR/Cas system and different effector proteins， reviews the different application strategies in nucleic acid POCT based on the specific recognition and cleavage characteristics of CRISPR/Cas system， and finally discusses the challenges and future research prospects of CRISPR/Cas in nucleic acid POCT.

Abstract:Small extracellular vesicles（sEV） are spherical membranous vesicles with lipid bilayer membrane structure and size less than 200 nm，which are secreted by cells actively. sEV are involved in intercellular signal communication and play an important role in the maintenance of normal physiological state and the progression of disease. Flow cytometry has the advantage of being able to directly perform multi-parameter，fast and high-resolution analysis on a large number of cells，but few studies have been applied to detect sEV that are much smaller than cells. In this paper，we review the application of flow cytometry in the detection of sEV reported by several research teams，including the direct detection of sEV by nanoflow cytometry. By conventional flow cytometry assisted by sEV clustering，DNA amplification and microspheres. By mass spectrometry flow cytometry. These methods show the possibility and advantages of flow cytometry in the detection of sEV，but at the same time，they are also faced with problems such as overlapping interference of fluorescence spectrum，and inability to accurately quantify，and still unable to break through size limits，which limit its large-scale research and application. This review is expected to help the academic community better understand the research progress of sEV flow cytometry and further promote the research of sEV.

Abstract:Tumor is one kind of disease that seriously endangers human health. It is a hot issue in the research of tumor therapy to explore new tumor therapy methods， improve its targeting and drug delivery efficiency，avoid tumor cell immune escape and reduce side effects. Bacteria-mediated cancer-targeted therapy is a novel experimental strategy for the treatment of cancers. Bacteria are preferentially accumulated in tumor microenvironments，characterized by hypoxia，low pH value，high permeability and immunosuppression. They can exert antitumor effects through inhibiting angiogenesis，promoting apoptosis and inhibiting immunomodulatory activity. Meanwhile，researchers can use genetic engineering techniques to modify bacteria to become engineered bacteria with higher targeting and better penetration. In addition，the emergence of using bacterial outer membrane vesicles loaded with chemotherapeutic drugs or combined with nanomaterials to fight tumors，as well as bacterial combination chemotherapy，radiotherapy， and photothermal/photodynamic therapy has led to rapid progress in research on bacterial therapy for tumors. This paper reviews the recent research progress in bacteria-mediated oncology therapy and looks forward to its future development.

Abstract:Objective To investigate the value of DNA differential methylation modification sites based on peripheral blood mononuclear cells（PBMCs） in the differential diagnosis of benign and malignant pulmonary nodules.Methods The genome-wide methylation status of 20 cases of benign pulmonary nodules and 34 cases of malignant pulmonary nodules were detected by 850k methylation bead chip. The specific methylation maps of benign and malignant pulmonary nodules derived from PBMCs were preliminarily constructed to obtain differentially methylated positions（DMPs）. Gene ontology（GO） analysis and Kyoto encyclopedia of genes and genomes（KEGG） analysis were performed to analyze the genes where DMPs were located. LASSO regression analysis was used to screen DMPs. The 36 patients with benign pulmonary nodules and 84 patients with malignant lung nodules were randomly divided into two groups of cohorts（test group and validation group）. The selected sites were analyzed and validated through the pyrophosphate sequencing method，the receiver operating characteristic（ROC） curve analysis was adopted，and the area under the ROC curve（AUC） was calculated to evaluate its prediction effectiveness of benign and malignant lung nodules.Results The PBMCs differential methylation profiles of patients with benign and malignant pulmonary nodules were significantly different in the cohort. A total of 421 DPMs were obtained with Δβ>0.06 and adjust P<0.01 as pre-screening condition. Six CpG loci were further screened by LASSO regression model. Two loci，cg05460181（AUC=0.793，P<0.0001）and cg08721802（AUC=0.893，P<0.0001），were obtained based on Pearson correlation analysis and further removal of loci with primer mismatch risk and primer synthesis difficulty. In the test phase，the methylation levels of the two sites in 16 benign pulmonary nodules and 34 malignant pulmonary nodules were tested by pyrosequencing，and it was found that cg08721802 had high diagnostic value for benign and malignant pulmonary nodules（AUC=0.778，sensitivity=85.29%，specificity=56.25%，P<0.01）. In the validation phase，the methylation level of cg08721802 was detected in an independent sample set of 22 patients with benign pulmonary nodules and 51 patients with malignant pulmonary nodules. It was found that cg08721802 still had diagnostic value in differentiating benign and malignant pulmonary nodules（AUC=0.768，sensitivity=84%，specificity=50%，P<0.01）. The diagnostic efficiency of cg08721802 locus was significantly higher than that of traditional tumor markers，and the combination of cg08721802 locus with CEA could significantly improve the diagnostic value of nodules with a size of 6-20 mm.Conclusion The methylation level of cg08721802 is significantly different in patients with benign and malignant pulmonary nodules，which can be used as a new molecular marker for the differential diagnosis of benign and malignant pulmonary nodules.

Abstract:Objective To investigate the role of N⁶-methyladenosine （m⁶A） mediated by methyltransferase-like 3（METTL3） in oxaliplatin（OXA） resistance of colorectal cancer.Methods Concentration gradient induction method was used to establish OXA resistant cell line HCT116/OXA，and CCK-8 was used to detect the drug resistance of cells. Dot blot and ELISA were used to analyze the expression level of m⁶A in HCT116/OXA and parental cells. RNA-seq and qRT-PCR were used to screen the differential regulators of m⁶A. Western blot was used to detect the expression level of METTL3. METTL3 was overexpressed in HCT116 by adenovirus infection technique，and the proliferation activity of each group was detected by CCK-8. The key genes and signal pathways of m⁶A modification and regulation mediated by METTL3 related to drug resistance were screened through the combined analysis of MeRIP-seq and RNA-seq data of METTL3 knocked out by HCT116 cells in GEO database and RNA-seq data of drug-resistant cells. The correlation between METTL3 and prognosis was analyzed by TCGA database.Results The resistance of HCT116/OXA cells to OXA was significantly higher than that of their parents（P<0.01）. Compared with HCT116 cells，the level of RNA m6A modification in HCT116/OXA cells was significantly up-regulated（P<0.01） and the expression of METTL3 was significantly increased. Overexpression of METTL3 significantly enhanced the resistance of HCT116 cells to OXA（P<0.01）. Differential genes selected from multiomics data conjoint analysis，related to drug resistance and regulated by METTL3-mediated m6A modification had significant correlation to ABC transporters，stem cell pluripotency，TGF-β signaling pathway and other signaling pathways. The high expression of METTL3 was significantly correlated with the poor prognosis of colorectal cancer patients（P<0.01）.Conclusion METTL3 mediated m⁶A methylation modification may promote the OXA resistance of colorectal cancer by regulating ABC transporter，stem cell pluripotency and TGF-β signaling pathway and other classical drug resistance signaling pathways.

Abstract:Objective To explore the application prospects and problems of artificial intelligence bone marrow cell recognition system，Morphogo，in the detection of minimal residual disease（MRD） of multiple myeloma.Methods A total of 65 cases of MRD of multiple myeloma confirmed by multiparameter flow cytometry（MFC） were collected，and their bone marrow Wright's staining smears were obtained. All bone marrow smears were automatically scanned and classified by Morphogo based on artificial intelligence platform. The positive threshold of MRD of AI and cytomorphology in multiple myeloma was set as the proportion of plasma cells，which was greater than 4.4%. The cases were divided into I 500 group，I 1000 group and I 2000 group according to the number of AI automatically recognized cells. The results of AI-MRD，morphological-MRD（M-MRD） and MFC-MRD in each group were tested by Kappa consistency test，and the sensitivity，specificity and accuracy of each group were calculated. Taking MFC-MRD and M-MRD results as the gold standard，the receiver operating characteristic (ROC) curve of AI-MRD was drawn and its area under the curve (AUC) value was calculated.Results After grouping，with the increase of the number of recognized cells，the Kappa value，sensitivity，specificity，accuracy and AUC of AI-MRD vs. MFC-MRD and AI-MRD vs. M-MRD increased. The Kappa consistency test of AI-MRD vs. MFC-MRD in I 2000 group showed that the Kappa value was 0.500（P=0.013），sensitivity was 71%，specificity was 80%，and accuracy was 75%. The Kappa consistency test results of AI-MRD vs. M-MRD showed that the Kappa value was 0.667（P=0.001），sensitivity was 100%，specificity was 75%，and accuracy was 83%. When MFC-MRD results were taken as the diagnostic criteria，the AUC of AI-MRD in I 2000 group was 0.800（P=0.002，95%CI=0.588-0.934），and the AUC of M-MRD was 0.779（P=0.005，95%CI=0.564-0.921）.Conclusion The detection of MRD of multiple myeloma by Morphogo has the characteristics of high accuracy，high speed and low cost. In the follow-up development，it should be considered to develop technologies such as cell histochemical staining and cellular immunity，so as to improve the diagnostic accuracy of MRD of artificial intelligence multiple myeloma.

Abstract:The detection of human leukocyte antigen-antibody（HLA-Ab）has become an important indicator for the diagnosis and detection of rejection after renal transplantation. Single antigen beads（SAB）is a highly sensitive and specific HLA-Ab detection method. However，the analysis and interpretation of SAB results are complex，and multiple factors need to be comprehensively considered. In this article，we will discuss the limitations，influencing factors and solutions for HLA-Ab detection using this method. It is hoped that the interpretation and application of SAB results can be further improved by discussing the above problems.

Abstract:Objective To provide new strategies for the early diagnosis and treatment of a variety of vascular embolic diseases，like cerebral venous sinus thrombosis（CVST），by constructing a rapid and sensitive thrombin detection technology.Methods The screened aptamer，which could recognize thrombin with high specificity，was used to construct the allosteric probe and to convert the thrombin signal into a nucleic acid signal. After the allosteric probe recognized thrombin，aptamer section in allosteric probe bound to thrombin，exposing the Cas12a active moiety. CRISPR-Cas12a system subsequently recognized the active moiety，and then activated its trans-cleavage property to cleave the surrounding single-stranded DNA fluorescent probes disorderly，resulting in separation of a fluorescent group（Cy3） and a quenching group（BHQ） which were originally labeled at both ends of the fluorescent probe. As a result，fluorescence signal of Cy3 reappeared. The intensity of the generated fluorescent signal was positively correlated with the concentration of thrombin present in the system.Results The fluorescence experiment confirmed that the designed allosteric probe showed high recognitive specificity and stability for thrombin. This method exhibited good detection performance in detection，with a limit of 0.23 pmol/L.Conclusion This method combines the advantages of high sensitivity，low cost and good portability，and can provide strong support for the detection and accurate diagnosis of thrombin-related diseases.

Abstract:Objective To investigate the association between the hemoglobin / red blood cell distribution width ratio（HRR）and early acute kidney injury（AKI）after coronary artery bypass grafting（CABG）.Methods All patients were enrolled from the Medical Information Mart for Intensive Care Database（MIMIC）-Ⅳ. The patients were divided into 2 groups according to whether AKI occurred. The general data of the 2 groups were compared and analyzed，the variables with statistical difference were included in logistic univariate regression analysis，and variables with P<0.05 were included in multivariate logistic regression analysis. Logistic regression model was used to evaluate the predictive value of HRR for AKI risk after CABG. Stratified regression model was used for subgroup analysis.Results A total of 5 623 patients were enrolled in the study，including 4 342 cases in the AKI group and 1 281 cases in the non-AKI group. The HRR level at admission in AKI group was significantly lower than that in non-AKI group（P<0.001）. Multivariate regression model showed that HRR was an independent risk factor for AKI after CABG（OR=0.92，95%CI=0.88-0.96，P<0.001）. Logistic regression model showed that in model Ⅲ（adjusting for potential confounders），low HRR level was still an independent influencing factor for AKI after CABG. Subgroup analysis found that the association between HRR and AKI was similar in most covariates.Conclusion Low HRR level is an independent risk factor for AKI after CABG.

Abstract:Objective To compare the relationship between AQP4-IgG expression and its clinical characteristics in the serum or cerebrospinal fluid of 142 patients with demyelinated optic neuritis（DON）.Methods We retrospectively collected and analyzed the clinical data and AQP4-IgG results of 142 DON patients admitted to the Department of Ophthalmology of The First Affiliated Hospital of Army Medical University from January 2016 to October 2020.Results ①AQP4-IgG positive was detected in 48 cases（33.8%），the female to male ratio was 5.9∶1，and 31 cases（64.6%） involved both eyes. The LogMAR visual acuity at the first visit was 0.48±0.64，and was 0.55±0.65 at the last visit. ②AQP4-IgG negative was detected in 94 cases（66.2%），the female to male ratio was 1.7∶1，and 53 cases（56.4%）involved both eyes. The LogMAR visual acuity at the first visit was 0.54±0.61，and was 0.39±0.49 at the last visit. ③The proportion of AQP4-IgG-positive female patients was significantly higher than that of AQP4-IgG-negative patients（χ2=7.827，P<0.01）； there was no statistical difference in the prevalence of both eyes（χ2=0.884，P>0.05）； there was no significant difference in LogMAR visual acuity at the time of onset（t=-0.721，P>0.05），but AQP4-IgG positive patients had worse visual prognosis（t=2.058，P<0.05）. AQP4-IgG positive patients had higher erythrocyte sedimentation rate（χ2=5.403，P<0.05）and a higher proportion of combined autoantibody results than AQP4-IgG negative patients（χ2=5.231，P<0.05），both of which had significant differences.Conclusion AQP4-IgG-positive patients with neuromyelitis optica spectrum disorders have a higher incidence of female morbidity，with worse visual prognosis，and may be combined with abnormal autoantibody results or autoimmune diseases. Accurate clinical classification based on AQP4-IgG detection is important for the treatment and prognosis.

Abstract:Objective To explore the key factors influencing the positive strength of direct antiglobulin test（DAT）in patients，and to provide guidance for clinical DAT-positive patients during antibiotic administration or red blood cell transfusion.Methods In the retrospective analysis of the data of 27 382 patients who underwent DAT from January 2015 to December 2020，we analyzed the patient's gender，age，clinical diagnosis，antibiotic usage，red blood cell transfusion，and DAT positive strength in statistics.Results A total of 27 382 patients underwent DAT，and 5 745（20.98%） were DAT-positive. Patients with different DAT strength were grouped by male and female，and Mann-Whitney U test was performed on them. The results showed that the DAT⁺ strength was significantly higher in the male than the female（U=2 764 704.5，P<0.001）. The DAT-positive patients were divided into 3 groups according to age（<18 years old group，18-60 years old group，>60 years old group）and the Kruskal-Wallis test results showed that the difference in DAT strength between different age groups was statistically significant（H=200.4，P<0.001）. The DAT positive strength of the <18 and >60 groups were higher than that of the 18–60 group. From the perspective of disease clinical diagnosis，the positive intensity of DAT was significantly different（H=70.82，P<0.001）. Mann-Whitney U analysis showed that the distribution of DAT strength was different between patients with or without usage of antibiotics，indicating that antibiotic usage increased DAT-positive strength（U=1 853 921.5，P<0.001）. DAT strength was higher in patients with red blood cell transfusion than in patients without red blood cell transfusion（U=3 315 953.5，P<0.001），but multiple red blood cell transfusions did not cause changes in DAT strength（U=108 911.5，P=0.68）.Conclusion In DAT-positive patients，the patient's gender，age，clinical diagnosis，antibiotic application，and red blood cell transfusion all affect their DAT strength. Repeated red blood cell transfusions haven't caused changes in DAT⁺ strength. Antibiotics and red blood cell transfusions should be used with caution in high DAT strength patients.

Abstract:Objective To establish a detection system based on multiple real-time fluorescence quantitative polymerase chain reaction（multiplex PCR）technique to rapidly and specifically detect pathogens in the blood of sepsis patients.Methods The main strains of pathogens isolated from blood samples were analyzed，and the spectrum of pathogens specific to sepsis was drawn. Specific primers were designed according to the sequences of the conserved regions to construct a multiplex PCR detection reaction system. Blood samples of 79 sepsis patients were collected，and 40 health subjects were included as negative and health controls during the same period. Then they were identified by the established detection system，and the blood culture method was compared.Results The detection time was shortened to 3 hours by multiplex PCR，which was 1/16 of blood culture. Compared with blood culture，the coincidence rate of multiplex PCR for target pathogen samples was 88%（22/25），the coincidence rate of negative samples was 100%（20/20），and the total coincidence rate was 94%. There was no significant difference between the two methods in the detection of target pathogens（P=0.250）with good consistency（Kappa=0.867，P<0.05）. The detection rates of multiple PCR method and blood culture method for clinically diagnosed sepsis samples were 23.0%（17/74）and 14.9%（11/74），respectively. The detection rates of the two methods were statistically significant（P=0.031）.Conclusion Multiplex PCR method can provide a reliable basis for earlier diagnosis and treatment to sepsis patients. Compared with “gold standard” blood culture method，the multiplex PCR detection system constructed in the project has shorter detection time，better coincidence rate and higher detection rate，which can provide reliable evidence for the early diagnosis and treatment of sepsis patients.

Abstract:Objective To study and analyze the pathogen distribution and drug resistance of infection after total hip arthroplasty.Methods A total of 142 cases of infection after artificial hip arthroplasty in Xinqiao Hospital，Army Medical University from January 2015 to March 2022 were analyzed retrospectively. The wound secretions and focus tissues were taken for bacterial species identification and drug resistance analysis.Results A total of 156 strains of pathogenic bacteria were isolated from 142 patients with infection after total hip arthroplasty and there were 11 patients with mixed infection，accounting for 7.75%. Gram-positive bacteria accounted for 64.10%（100 strains），of which Staphylococcus aureus and Staphylococcus epidermidis accounted for 33.33% and 16.67%，respectively. Gram-negative bacteria accounted for 33.98%，of which Pseudomonas aeruginosa and Escherichia coli accounted for 14.74% and 10.26%，respectively. Staphylococcus aureus and Staphylococcus epidermidis in gram-positive bacteria were highly resistant to penicillin，ampicillin，oxacillin，erythromycin，amoxicillin/clavulanic acid（all more than 50%）and sensitive to quinoloptin/daptidine，vancomycin and linazolidine. Pseudomonas aeruginosa in gram-negative bacteria was sensitive to antibiotics such as cefoperazone，cefuroxime and piperacillin，while Escherichia coli was highly resistant to tetracycline，ampicillin，ciprofloxacin and gentamicin（all more than 50%），and sensitive to cefoperazone/sulbactam，minocycline，tetracycline，aztreonam，sulfamethoxazole and imipenem.Conclusion Gram-positive bacteria，including Staphylococcus aureus and Staphylococcus epidermidis，are the main infections after total hip arthroplasty. Quinuprotin/daptidine，vancomycin and linezolid can be used as the first choice for empirical treatment of infection after total hip arthroplasty.

Abstract:Objective To explore the clinical characteristics of Klebsiella pneumoniae bloodstream infection in Yongchuan Hospital of Chongqing Medical University and the risk factors affecting the prognosis.Methods The clinical and laboratory data of 108 patients with Klebsiella pneumoniae bloodstream infection who were admitted to hospital from January 2019 to July 2021 were retrospectively analyzed. The patients were divided into clinical improvement group and poor prognosis group according to clinical outcomes. Logistic regression and receiver operator characteristic(ROC) curve were used to analyze the predictors of poor outcome.Results Patients with Klebsiella pneumoniae bloodstream infection were mainly distributed in ICU（19.4%），department of infectious diseases（13.9%），department of hepatobiliary surgery（10.3%），department of hematology（8.4%） and so on； 86.1% patients suffered from underlying diseases，including diabetes mellitus（38.9%），hypertension（25.0%），and malignant solid tumor（14.8%）. The resistance rates of 108 strains of bloodstream infection-caused Klebsiella pneumoniae and 1 631 strains of non-bloodstream infection-caused Klebsiella pneumoniae were 8.3% and 14.8%，respectively. There were significant differences in age，hospital stay，ICU admission and anemia between poor prognosis group and clinical improvement group（P < 0.05）. The multivariate logistic regression analysis showed that age（OR=1.044，95%CI=0.002-0.083，P=0.038），length of hospital stay（OR=0.936，95%CI=-0.110--0.023，P=0.003），admission to ICU（OR=8.794，95%CI=0.855-3.493，P=0.001），and anemia（OR=5.638，95%CI=0.684-2.775，P=0.001）were independent risk factors for the poor prognosis of Klebsiella pneumoniae bloodstream infection. Furthermore，elevated PCT（OR=0.094，95%CI=0.021-0.166，P=0.011）was shown to be a risk factor for death from Klebsiella pneumoniae bloodstream infection.Conclusion The elderly，anemia and ICU stay are risk factors for poor prognosis in patients with Klebsiella pneumoniae bloodstream infection. Early etiological examination and appropriate empirical treatment can improve the prognosis.

Abstract:Objective To analyze the distribution characteristics and drug resistance of pathogenic bacteria of bloodstream infection in hospitalized patients with hematological diseases in Chinese PLA General Hospital，and to provide reference for the rational selection of antibiotics during clinical treatment.Methods A retrospective study was performed by reviewing the results of blood culture and drug susceptibility of hospitalized patients with hematological and non-hematological diseases from 2019 to 2021. VITEK-2 system was used for identification and antimicrobial susceptibility test.Results Gram-negative bacilli（71.2%） were the main pathogenic bacteria in patients with hematological diseases suffered from bloodstream infection，followed by gram-positive bacteria（26.8%） and fungi（2.0%）. The main pathogens were Escherichia coli，Klebsiella pneumoniae，coagulase-negative staphylococcus， Pseudomonas aeruginosa，etc. The main gram-negative isolates were more sensitive to amikacin，imipenem and meropenem， those main gram-positive ones to vancomycin and linezolid，and fungal isolates to amphotericin B and voriconazole. Staphylococcus were not resistant to vancomycin，tigecycline or linezolid. Comparison was made between the pathogens of bloodstream infection in patients with hematological diseases and those with non-hematological diseases，which found that the proportion of Pseudomonas aeruginosa and Stenotrophomonas maltophilia was significantly higher in the former，while that of coagulase-negative Staphylococci and Candida albicans was significantly lower（P<0.05）. The resistance rate of Escherichia coli to carbapenems and quinolones in patients with hematological diseases was higher than that of patients with non-hematological diseases，and the difference was statistically significant（P<0.05）；the resistance rate of Klebsiella pneumoniae and Pseudomonas aeruginosa to antibacterial drugs such as carbapenems and quinolones was lower than that of patients with non-hematological diseases， and the difference was statistically significant（P<0.05）.Conclusion Gram-negative bacteria are the most common pathogens causing bloodstream infection in patients with hematological diseases，especially Escherichia coli， which is nearly the same to that in patients with non-hematological diseases in our hospital. Gram-negative bacteria have high sensitivity to amikacin，imipenem，meropenem，piperacillin/tazobactam，and gram-positive bacteria have high sensitivity to vancomycin and linezolid. This study finds that the drug resistance rate of Escherichia coli to carbapenems and quinolones in patients with hematological diseases was higher than that of patients with non-hematological diseases，and the attention and monitoring of carbapenems and quinolones should be strengthened in clinical diagnosis and treatment. Timely monitoring of pathogens and drug resistance，reasonable selection of antibiotics， and early control of bloodstream infections are very important for prognosis.