Objective To specifically extract and analyze nascent proteins synthesized by bone marrow mesenchymal stem cells(BMSCs)after transplantation into ischemic hearts using a technique employing mutant methionyl-tRNA synthetase(MetRSL247G)for nascent protein labeling,in order to explore the potential mechanisms of action in BMSCs post-transplantation.Methods Point mutation at position 274 of the MetRS gene in BMSCs was induced via lentiviral infection to enable azidonorleucine(ANL)-mediated labeling of nascent proteins in BMSCs.The labeling efficiency was verified by means of fluorescent non-canonical amino-acid tagging(FUNCAT).Thirty healthy female C57BL/6J mice(8-10 weeks old)were divided into control and experimental groups,with 15 mice in each group.The acute myocardial infarction model was constructed by ligating the left anterior descending coronary artery in experimental group,while control mice underwent only thoracotomy without coronary ligation.After modeling,both groups received intramyocardial injections of MetRSL247G-modified BMSCs(MetRSL247G-BMSCs)at 3 different sites in the peri-infarct ischemic region.Mice were intraperitoneally injected with ANL every 6 hours for 4 times on postoperative days 0,2,and 6(n=5 for each time point)respectively,euthanized 24 h after the last injection,and cardiac tissues were isolated.The newly synthesized and labeled proteins produced by BMSCs after transplantation into the myocardium of experimental and control groups were collected,using an enrichment technique for ANL-tagged proteins and liquid chromatography-tandem mass spectrometry(LC-MS)analysis.Gene ontology(GO)analysis,Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis,protein-protein interaction(PPI)analysis,and heatmap visualization analysis were performed to identify differentially expressed proteins at the 3 time points and screen key pathways and genes.Results Under fluorescence microscopy,the MetRSL247G lentivirus-infected BMSCs were observed to be labelled with mCherry signals,confirming the successful construction of the MetRSL247G-BMSCs cell line.Green fluorescent signals were detected only in nascent proteins in culture medium containing both MetRSL247G-BMSCs and ANL,validating the sensitivity and specificity of the labeling method.GO analysis revealed that differentially expressed proteins were primarily involved in basic cellular biological processes such as extracellular exosome formation,extracellular matrix organization,and focal adhesion.KEGG and PPI analyses indicated that the differential proteins were mainly involved in complement and coagulation cascade pathway,actin cytoskeleton regulation pathway,and apoptosis pathway.Heatmap analysis showed significantly upregulated expression of anti-apoptosis and cell adhesion-related factors in experimental group on day 1(P＜0.05),upregulated anti-apoptotic factors,pro-apoptotic factors,and cell adhesion-related factors on day 3(P＜0.05),and upregulated anti-apoptotic factors,cell differentiation-related factors,and cell adhesion-related factors on day 7(P＜0.05)compared with control group.Expression of apoptosis-inducing factor 1 was significantly downregulated on days 1 and 7(P＜0.05).On day 3,most differentially expressed proteins,including anti-apoptosis factors(Protein S100-A11,Clusterin,Gelsolin),pro-apoptosis factor(Cathepsin B),cell differentiation-related factor(Transgelin-2),and cell adhesion-related factors(Cofilin-1,Periostin,Fibronectin)were significantly upregulated(P＜0.05).Conclusions The MetRSL247G mutation enables BMSCs to incorporate ANL and synthesize labeled proteins,confirming the feasibility of this nascent protein labeling technique.Nascent proteins of BMSCs in ischemic myocardium primarily contribute to extracellular exosome secretion and extracellular matrix organization.BMSCs may adapt to and respond to ischemic and hypoxic environments by influencing complement and coagulation cascades,activating inflammatory factors,regulating actin cytoskeleton structure,and modulating apoptosis,thereby maintaining the survival of BMSCs.

Objective:To investigate the clinically curative effect of composite dressing of adipose mesenchymal stem cell exosomes and chitosan hydrogel in treating deep Ⅱ burn wound.Methods:A total of 108 patients with superficially deep Ⅱ burns,who admitted to Tangdu Hospital,Air Force Medical University within 48 hours during March 2022 and October 2024,were selected.Patients were randomly divided into conventional treatment group and the combined treatment group by using a random number table,with 54 patients in each group.All patients underwent enzymatic debridement(collagenase ointment)to conduct conventional treatment.The combined treatment group received treatment with composite dressings of adipose-derived mesenchymal stem cell exosomes(ADSCs-Exo)combined with chitosan hydrogel,while the conventional treatment group received treatment with silver sulfadiazine dressings(SSD)on the basis of conventional treatment.The healing rates of wound,Vancouver Scar Scale(VSS)scores,the levels of serum inflammatory factors included interleukin-6(IL-6),interleukin-1β(IL-1β),C-reactive protein(CRP),and tumor necrosis factor-α(TNF-α),as well as curative efficacy rates,and adverse reactions between two groups were compared at different time points after treatment.Results:There was not statistically significant difference in healing rates of wound between the two groups at the 7th day after treatment(P>0.05).At the 14th day and the 21th day after treatment,the average healing rates of wound in the combined treatment group were respectively(67.69±8.57)%and(89.46±7.54)%,which were higher than(59.50±4.93)%and(75.52±9.11)%in the conventional treatment group,and the differences were statistically significant(t=6.087,8.662,P<0.05).The average VSS score was(6.42±1.20)points in the combined treatment group after treatment,which was lower than that in the conventional treatment group(8.94±1.58),and the difference was statistically significant(t=9.33,P<0.05).Before treatment,there were not statistically significant difference in VAS scores and the levels of serum inflammatory factor between the two groups(P>0.05).At the 7th day,the 14th day and the 21th day after treatment,the VAS scores in the combined treatment group were significantly lower than those in the conventional treatment group(t=10.008,12.004,13.899,P<0.05),respectively.At the 21th day after treatment,the levels of IL-6,IL-1β,CRP,and TNF-α of the combined treatment group were significantly lower than those of the conventional treatment group(t=3.400,4.490,7.293,5.900,P<0.05).The efficacy rate of clinical treatment in the combined treatment group was 96.30%,which was higher than 83.33%of the conventional treatment group,with a statistical significance(x2=7.942,P<0.05).The incidence of adverse reaction in the combined treatment group was 14.81%,which was lower than 24.07%of the conventional treatment group,without statistical significance(P>0.05).Conclusion:Compared with conventional silver sulfadiazine dressing,the composite dressing of adipose mesenchymal stem cell exosomes and chitosan hydrogel can quickly promote the re-epithelialization process in treating patients with superficially deep Ⅱ burns at the middle to late stage,and improve the healing rate,and relieve the inflammatory reaction and pain perception of patients for wound,and enhance efficiency and safety.

INTRODUCTION: Lecanemab has shown promise in treating early Alzheimer's disease (AD), but its safety and efficacy in Chinese populations remain unexplored. This study aimed to evaluate the safety and 6-month clinical outcomes of lecanemab in Chinese patients with mild cognitive impairment (MCI) or mild AD. METHODS: In this single-arm, real-world study, participants with MCI due to AD or mild AD received biweekly intravenous lecanemab (10 mg/kg). The study was conducted at Hainan Branch, Ruijin Hospital Shanghai Jiao Tong University School of Medicine. Patient enrollment and baseline assessments commenced in November 2023. Safety assessments included monitoring for amyloid-related imaging abnormalities (ARIA) and other adverse events. Clinical and biomarker changes from baseline to 6 months were evaluated using cognitive scales (mini-mental state examination [MMSE], montreal cognitive assessment [MoCA], clinical dementia rating-sum of boxes [CDR-SB]), plasma biomarker analysis, and advanced neuroimaging. RESULTS: A total of 64 patients were enrolled in this ongoing real-world study. Safety analysis revealed predominantly mild adverse events, with infusion-related reactions (20.3%, 13/64) being the most common. Of these, 69.2% (9/13) occurred during the initial infusion and 84.6% (11/13) did not recur. ARIA-H (microhemorrhages/superficial siderosis) and ARIA-E (edema/effusion) were observed in 9.4% (6/64) and 3.1% (2/64) of participants, respectively, with only two symptomatic cases (one ARIA-E presenting with headache and one ARIA-H with visual disturbances). After 6 months of treatment, cognitive scores remained stable compared to baseline (MMSE: 22.33 ± 5.58 vs . 21.27 ± 4.30, P = 0.733; MoCA: 16.38 ± 6.67 vs . 15.90 ± 4.78, P = 0.785; CDR-SB: 2.30 ± 1.65 vs . 3.16 ± 1.72, P = 0.357), while significantly increasing plasma amyloid-β 42 (Aβ42) (+21.42%) and Aβ40 (+23.53%) levels compared to baseline. CONCLUSIONS: Lecanemab demonstrated a favorable safety profile in Chinese patients with early AD. Cognitive stability and biomarker changes over 6 months suggest potential efficacy, though high dropout rates and absence of a control group warrant cautious interpretation. These findings provide preliminary real-world evidence for lecanemab's use in China, supporting further investigation in larger controlled studies. REGISTRATION ClinicalTrials.gov , NCT07034222.
Humans ; Alzheimer Disease/drug therapy* ; Male ; Female ; Aged ; Middle Aged ; Cognitive Dysfunction/drug therapy* ; Aged, 80 and over ; Amyloid beta-Peptides/metabolism* ; Biomarkers ; East Asian People

Aim To investigate the potential role and related mechanisms of protein phosphatase 2Cm(PP2Cm)overexpression in atorvastatin-induced insu-lin resistance.Methods Male C57BL/6J mice,fibro-blast growth factor 21 knockout(FGF21-KO)mice,and wildtype(WT)mice were raised for 12 weeks to construct models.Groups included atorvastatin,con-trol,atorvastatin+PP2Cm overexpression(OE),FGF21-KO+vehicle,FGF21-KO+PP2Cm OE,WT+vehicle,WT+PP2Cm OE.Body weight,fasting blood glucose levels,fasting insulin levels,and intraperitoneal glucose tolerance tests(IPGTT)were measured in 4,8 and 12 weeks.The concentrations of branched-chain a-mino acids(BCAA)in cells,tissues and serum,as well as the mRNA and protein expression of BCAA cat-abolic enzymes,were determined by qRT-PCR,Western blot and ELISA after atorvastatin treatment.Further-more,the effects of PP2Cm overexpression on these in-dicators were explored,and the FGF21 was verified in vivo and in vitro.Results Atorvastatin induced insu-lin resistance in mice,altered insulin,glucose tolerance and increased BCAA levels.PP2Cm overexpression mitigated these changes.In the Atorvastatin+PP2Cm OE group,FGF21 mRNA,protein and concentration were all significantly upregulated.Regardless of PP2Cm overexpression,the knockout of FGF21 signifi-cantly increased BCAA expression levels,both fasting insulin and blood glucose levels were significantly high-er than those in WT group.Conclusions FGF21 may be an important regulator of PP2Cm involved in atorv-astatin-induced insulin resistance.PP2Cm overexpres-sion alleviates the effects of atorvastatin-induced insulin resistance by regulating FGF21.

Objective:To report the nationwide surveillance results of pathogenic profiles and antimicrobial resistance patterns of Gram-positive bloodstream infections in China in 2023.Methods:The clinical isolates of Gram-posttive bacteria from blood cultures were collected in member hospitals of National Bloodstream Infection Bacterial Resistant Investigation Collaborative System（BRICS）during January to December 2023. Antimicrobial susceptibility testing was performed using the dilution method recommended by the Clinical and Laboratory Standards Institute（CLSI）. Statistical analyses were conducted using WHONET 5.6 and SPSS 25.0 software.Results:A total of 4 385 Gram-positive bacterial isolates were obtained from 60 participating center. The top five pathogens were Staphylococcus aureus（ n=1 544，35.2%），coagulase-negative Staphylococci（ n=1 441，32.9%）， Enterococcus faecium（ n=574，13.1%）， Enterococcus faecalis（ n=385，8.8%），and α-hemolytic Streptococci（ n=187，4.3%）. The prevalence of methicillin-resistant Staphylococcus aureus（MRSA）and methicillin-resistant coagulase-negative Staphylococci（MRCNS）was 26.2%（405/1 544）and 69.8%（1 006/1 441），respectively. Notably，all Staphylococci remained susceptible to glycopeptide or daptomycin. Staphylococcus aureus demonstrated excellent susceptibility（>97.0%）to cephalobiol，rifampicin，trimethoprim-sulfamethoxazole，linezolid，minocycline，tigecycline，and eravacycline. No Enterococcus exhibiting resistance to linezolid were detected. Glycopeptide resistance was uncommon but more frequent in Enterococcus faecium（resistance to vancomycin and teicoplanin：both 1.7%）compared to Enterococcus faecalis（both 0.3%）. The detection rates of MRSA and MRCNS exhibited significant regional variations across the country（ χ2=17.674 and 148.650，respectively，both P<0.001）. No vancomycin-resistant Enterococci were detected in central China. Institutional comparison demonstrated higher prevalence of MRSA（ χ2=14.111， P<0.001）and MRCNS（ χ2=4.828， P=0.028）in provincial hospitals than that in municipal hospitals. Socioeconomic analysis identified elevated detection rates of both MRSA（ χ2=18.986， P<0.001）and MRCNS（ χ2=4.477， P=0.034）in less developed regions（per capita GDP

Objective:To report the results of bacterial resistant investigation collaborative system（BRICS）on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2023，and provide reference for clinical tretment of bloodstream infections and prevention and control of bacterial resistance.Methods:The clinical isolates of Gram-negative bacteria from blood cultures in member hospitals of BRICS were collected during January 2023 to December 2023. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 were used to analyze the data.Results:During the study period，11 492 strains of Gram-negative bacteria were collected from 60 hospitals，of which 10 098（87.9%）were Enterobacterales and 1 394（12.1%）were non-fermentative bacteria. The top 5 bacterial species were Escherichia coli（50.0%）， Klebsiella pneumoniae（26.1%）， Pseudomonas aeruginosa（5.1%）， Acinetobacter baumannii complex（5.0%）and Enterobacter cloacae complex（4.1%）. The ESBL-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus mirablilis were 46.8%（2 685/5 741），18.3%（549/2 999）and 44.0%（77/175），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（76/5 741）and 15.0%（450/2 999）；32.9%（25/76）and 78.0%（351/450）of CREC and CRKP were sensitive to ceftazidime/avibactam combination，respectively. 94.7%（72/76）and 90.2%（406/450）of CREC and CRKP were sensitive to aztreonam/avibactam combination. Furthermore，57.9%（44/76）and 79.1%（356/450）were sensitive to imipenem/relebactam combination. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 64.6%（370/573），while more than 80.0% of CRAB complex was sensitive to tigecycline，eravacycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 17.0%（99/581）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of important Gram-negative bacteria resistance among different regions in China，with statistically significant differences in the prevalence of CREC，CRKP，CRPA and CRAB complex（ χ2=10.6，28.6，10.8 and 19.3， P<0.05）. The prevalence of ESBL-producing Escherichia coli， CREC，CRAB complex and CRKP were higher in provincial hospitals than those in municipal hospitals（ χ2=12.5，9.8，12.7 and 57.8，all P<0.01）. Conclusions:Gram-negative bacteria are the main pathogens causing bloodstream infections in China，and Escherichia coli is ranked in the top，while the trend of Klebsiella pneumoniae increases continuously with time. CRKP infection shows a slow upward trend，CREC infecton maintains a low prevalence level，and CRAB complex infection continues to exhibit a high prevalence rate. The composition and resistance patterns of pathogens causing bloodstream infections vary to some extent across different regions and levels of hospitals in China.

Objective:To investigate the clinically curative effect of composite dressing of adipose mesenchymal stem cell exosomes and chitosan hydrogel in treating deep Ⅱ burn wound.Methods:A total of 108 patients with superficially deep Ⅱ burns,who admitted to Tangdu Hospital,Air Force Medical University within 48 hours during March 2022 and October 2024,were selected.Patients were randomly divided into conventional treatment group and the combined treatment group by using a random number table,with 54 patients in each group.All patients underwent enzymatic debridement(collagenase ointment)to conduct conventional treatment.The combined treatment group received treatment with composite dressings of adipose-derived mesenchymal stem cell exosomes(ADSCs-Exo)combined with chitosan hydrogel,while the conventional treatment group received treatment with silver sulfadiazine dressings(SSD)on the basis of conventional treatment.The healing rates of wound,Vancouver Scar Scale(VSS)scores,the levels of serum inflammatory factors included interleukin-6(IL-6),interleukin-1β(IL-1β),C-reactive protein(CRP),and tumor necrosis factor-α(TNF-α),as well as curative efficacy rates,and adverse reactions between two groups were compared at different time points after treatment.Results:There was not statistically significant difference in healing rates of wound between the two groups at the 7th day after treatment(P>0.05).At the 14th day and the 21th day after treatment,the average healing rates of wound in the combined treatment group were respectively(67.69±8.57)%and(89.46±7.54)%,which were higher than(59.50±4.93)%and(75.52±9.11)%in the conventional treatment group,and the differences were statistically significant(t=6.087,8.662,P<0.05).The average VSS score was(6.42±1.20)points in the combined treatment group after treatment,which was lower than that in the conventional treatment group(8.94±1.58),and the difference was statistically significant(t=9.33,P<0.05).Before treatment,there were not statistically significant difference in VAS scores and the levels of serum inflammatory factor between the two groups(P>0.05).At the 7th day,the 14th day and the 21th day after treatment,the VAS scores in the combined treatment group were significantly lower than those in the conventional treatment group(t=10.008,12.004,13.899,P<0.05),respectively.At the 21th day after treatment,the levels of IL-6,IL-1β,CRP,and TNF-α of the combined treatment group were significantly lower than those of the conventional treatment group(t=3.400,4.490,7.293,5.900,P<0.05).The efficacy rate of clinical treatment in the combined treatment group was 96.30%,which was higher than 83.33%of the conventional treatment group,with a statistical significance(x2=7.942,P<0.05).The incidence of adverse reaction in the combined treatment group was 14.81%,which was lower than 24.07%of the conventional treatment group,without statistical significance(P>0.05).Conclusion:Compared with conventional silver sulfadiazine dressing,the composite dressing of adipose mesenchymal stem cell exosomes and chitosan hydrogel can quickly promote the re-epithelialization process in treating patients with superficially deep Ⅱ burns at the middle to late stage,and improve the healing rate,and relieve the inflammatory reaction and pain perception of patients for wound,and enhance efficiency and safety.

Aim To investigate the potential role and related mechanisms of protein phosphatase 2Cm(PP2Cm)overexpression in atorvastatin-induced insu-lin resistance.Methods Male C57BL/6J mice,fibro-blast growth factor 21 knockout(FGF21-KO)mice,and wildtype(WT)mice were raised for 12 weeks to construct models.Groups included atorvastatin,con-trol,atorvastatin+PP2Cm overexpression(OE),FGF21-KO+vehicle,FGF21-KO+PP2Cm OE,WT+vehicle,WT+PP2Cm OE.Body weight,fasting blood glucose levels,fasting insulin levels,and intraperitoneal glucose tolerance tests(IPGTT)were measured in 4,8 and 12 weeks.The concentrations of branched-chain a-mino acids(BCAA)in cells,tissues and serum,as well as the mRNA and protein expression of BCAA cat-abolic enzymes,were determined by qRT-PCR,Western blot and ELISA after atorvastatin treatment.Further-more,the effects of PP2Cm overexpression on these in-dicators were explored,and the FGF21 was verified in vivo and in vitro.Results Atorvastatin induced insu-lin resistance in mice,altered insulin,glucose tolerance and increased BCAA levels.PP2Cm overexpression mitigated these changes.In the Atorvastatin+PP2Cm OE group,FGF21 mRNA,protein and concentration were all significantly upregulated.Regardless of PP2Cm overexpression,the knockout of FGF21 signifi-cantly increased BCAA expression levels,both fasting insulin and blood glucose levels were significantly high-er than those in WT group.Conclusions FGF21 may be an important regulator of PP2Cm involved in atorv-astatin-induced insulin resistance.PP2Cm overexpres-sion alleviates the effects of atorvastatin-induced insulin resistance by regulating FGF21.

Objective:To report the nationwide surveillance results of pathogenic profiles and antimicrobial resistance patterns of Gram-positive bloodstream infections in China in 2023.Methods:The clinical isolates of Gram-posttive bacteria from blood cultures were collected in member hospitals of National Bloodstream Infection Bacterial Resistant Investigation Collaborative System（BRICS）during January to December 2023. Antimicrobial susceptibility testing was performed using the dilution method recommended by the Clinical and Laboratory Standards Institute（CLSI）. Statistical analyses were conducted using WHONET 5.6 and SPSS 25.0 software.Results:A total of 4 385 Gram-positive bacterial isolates were obtained from 60 participating center. The top five pathogens were Staphylococcus aureus（ n=1 544，35.2%），coagulase-negative Staphylococci（ n=1 441，32.9%）， Enterococcus faecium（ n=574，13.1%）， Enterococcus faecalis（ n=385，8.8%），and α-hemolytic Streptococci（ n=187，4.3%）. The prevalence of methicillin-resistant Staphylococcus aureus（MRSA）and methicillin-resistant coagulase-negative Staphylococci（MRCNS）was 26.2%（405/1 544）and 69.8%（1 006/1 441），respectively. Notably，all Staphylococci remained susceptible to glycopeptide or daptomycin. Staphylococcus aureus demonstrated excellent susceptibility（>97.0%）to cephalobiol，rifampicin，trimethoprim-sulfamethoxazole，linezolid，minocycline，tigecycline，and eravacycline. No Enterococcus exhibiting resistance to linezolid were detected. Glycopeptide resistance was uncommon but more frequent in Enterococcus faecium（resistance to vancomycin and teicoplanin：both 1.7%）compared to Enterococcus faecalis（both 0.3%）. The detection rates of MRSA and MRCNS exhibited significant regional variations across the country（ χ2=17.674 and 148.650，respectively，both P<0.001）. No vancomycin-resistant Enterococci were detected in central China. Institutional comparison demonstrated higher prevalence of MRSA（ χ2=14.111， P<0.001）and MRCNS（ χ2=4.828， P=0.028）in provincial hospitals than that in municipal hospitals. Socioeconomic analysis identified elevated detection rates of both MRSA（ χ2=18.986， P<0.001）and MRCNS（ χ2=4.477， P=0.034）in less developed regions（per capita GDP

Objective:To report the results of bacterial resistant investigation collaborative system（BRICS）on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2023，and provide reference for clinical tretment of bloodstream infections and prevention and control of bacterial resistance.Methods:The clinical isolates of Gram-negative bacteria from blood cultures in member hospitals of BRICS were collected during January 2023 to December 2023. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 were used to analyze the data.Results:During the study period，11 492 strains of Gram-negative bacteria were collected from 60 hospitals，of which 10 098（87.9%）were Enterobacterales and 1 394（12.1%）were non-fermentative bacteria. The top 5 bacterial species were Escherichia coli（50.0%）， Klebsiella pneumoniae（26.1%）， Pseudomonas aeruginosa（5.1%）， Acinetobacter baumannii complex（5.0%）and Enterobacter cloacae complex（4.1%）. The ESBL-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus mirablilis were 46.8%（2 685/5 741），18.3%（549/2 999）and 44.0%（77/175），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（76/5 741）and 15.0%（450/2 999）；32.9%（25/76）and 78.0%（351/450）of CREC and CRKP were sensitive to ceftazidime/avibactam combination，respectively. 94.7%（72/76）and 90.2%（406/450）of CREC and CRKP were sensitive to aztreonam/avibactam combination. Furthermore，57.9%（44/76）and 79.1%（356/450）were sensitive to imipenem/relebactam combination. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 64.6%（370/573），while more than 80.0% of CRAB complex was sensitive to tigecycline，eravacycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 17.0%（99/581）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of important Gram-negative bacteria resistance among different regions in China，with statistically significant differences in the prevalence of CREC，CRKP，CRPA and CRAB complex（ χ2=10.6，28.6，10.8 and 19.3， P<0.05）. The prevalence of ESBL-producing Escherichia coli， CREC，CRAB complex and CRKP were higher in provincial hospitals than those in municipal hospitals（ χ2=12.5，9.8，12.7 and 57.8，all P<0.01）. Conclusions:Gram-negative bacteria are the main pathogens causing bloodstream infections in China，and Escherichia coli is ranked in the top，while the trend of Klebsiella pneumoniae increases continuously with time. CRKP infection shows a slow upward trend，CREC infecton maintains a low prevalence level，and CRAB complex infection continues to exhibit a high prevalence rate. The composition and resistance patterns of pathogens causing bloodstream infections vary to some extent across different regions and levels of hospitals in China.