To explore the dose-response correlation between appendicular skeletal muscle index (ASMI) and muscle strength in older adults.

Objective:To investigate the changes in hepatic phase II detoxification enzymes and their mechanism in metabolic associated steatohepatitis (MASH) induced by a methionine-choline-deficient (MCD) diet in mice.Methods:Ten C57BL/6J mice were randomly divided into two groups, with five mice in each group, and fed with a control diet (NCD group) and a methionine-choline-deficient diet (MCD group) for four consecutive weeks to establish the MASH model in mice. Mice body weight was recorded weekly. Mice peripheral blood and liver tissue samples were collected after four weeks. The liver histopathological changes were observed by hematoxylin-eosin staining and Sirius red staining in liver tissue. The levels of plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST) and triglycerides were measured by an automatic biochemical analyzer. Triglyceride and total cholesterol were used to evaluate the lipid accumulation condition in the liver of mice with Oil red O staining. Real-time fluorescence quantitative PCR was used to detect the expression of liver inflammatory factors interleukin (IL)-1β and monocyte chemoattractant protein-1 (MCP-1) condition. Transcriptome sequencing and bioinformatics were used to analyze the changes in gene expression profiles in the liver of mice and screen differentially expressed genes. The expression conditions of phase Ⅱ detoxification enzymes glutathione S-transferase mu 4 (GSTM4), dihydronicotinamide riboside:quinone oxidoreductases (NQO-2), sulfotransferase 1β1 (SULT1β1), and uridine diphosphate glucuronosyltransferase 2 family, polypeptide A3(UGT2A3) were verified by real-time fluorescent quantitative PCR. Plasma malondialdehyde content, total antioxidant capacity (T-AOC), plasma and liver glutathione content were determined using commercial kits. The expression of nuclear factor E2-related factor 2 (Nrf2), GSTM4, and UGT1A6 was examined by Western blotting. The independent sample t-test was used for comparison between the groups. Results:The body weight of mice in the MCD group showed a gradual downward trend, while the body weight of mice in the NCD group did not change significantly following four weeks of different dietary feeding. The MCD group mice liver had yellow-white appearance with round edges. The liver/body mass index was significantly lower in the NCD group ( t=3.216, P<0.01). Hematoxylin-eosin staining showed that hepatocytes in the MCD group had an occurrence of fatty degeneration accompanied by inflammatory cell infiltration, with a higher NAFLD activity score (NAS) compared to the NCD group ( t=7.155, P<0.001). Sirius red staining showed that the the liver of the MCD group had mildly increased periportal fibers. Plasma biochemical tests indicated that plasma ALT, AST, and triglyceride levels were significantly higher in the MCD group than those in the NCD group ( t=8.920, P<0.001; t=6.696, P<0.001; t=3.904, P<0.01). Oil red O staining showed that a large number of lipid droplets accumulated in the liver tissue of the MCD group and were more severe than those in the NCD group ( t=7.405, P<0.001). The triglyceride content was significantly higher in the liver of the mice in the MCD group than that in the NCD group ( t=3.559, P<0.01), and the expression of inflammatory factors IL-1β and MCP-1 was significantly increased ( t=2.562 and 2.391, respectively, P<0.05). Transcriptome sequencing analysis showed that the expression profile of genes related to lipid metabolism was changed in the liver tissue of the mice in the MCD group. The expression of multiple phase Ⅱ detoxification enzymes was significantly downregulated. Real-time fluorescence quantitative PCR verification demonstrated that the expression of four phase Ⅱ detoxification enzymes GSTM4, NQO2, SUIL1β1, and UGT2A3 were significantly lower in the liver of the mice in the MCD group than those in the NCD group ( t=2.498, 3.570, 3.768, and 4.166, respectively, P<0.05). The detection kit showed that compared with the NCD group, the malondialdehyde content in the liver of mice in the MCD group increased ( t=3.601, P<0.01), while the plasma total glutathione ( t=11.93, P<0.001) and reduced glutathione levels were significantly reduced ( t=3.635, P<0.01). The total antioxidant capacity of the liver decreased ( t=2.872, P<0.05), and the total glutathione and reduced glutathione levels in the liver were significantly increased ( t=3.175 and 3.064, P<0.05). Western blotting showed that the expression of Nrf2, GSTM4, and UGT1A6 proteins was significantly lower in the MCD group than that in the NCD group ( t=3.385, 2.990, 2.168, P<0.05). Conclusions:The expressions of multiple phase Ⅱ detoxification enzymes and antioxidant capacity are reduced in the liver of MASH mice induced by the MCD diet, and its mechanism is related to the down-regulation of the expression of the upstream regulatory factor Nrf2 protein.

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 effects of Chuangling Ye(CLY)on diabetic foot ulcer(DFU)model mice based on the nuclear factor erythroid 2-related factor 2(Nrf2)/solute carrier family 7 member 11(SLC7A11)/glutathione peroxidase 4(GPX4)pathway and explore its potential mechanism.METHODS In animal experiments,streptozotocin(STZ)-induced diabetic mice with full-thickness skin defects were divided into control,model,positive control(recombinant human epidermal growth factor,rhEGF),and CLY low-and high-dose groups(n=10).After 14 days of intervention,wound healing rate was measured.Serum inflammatory factors(IL-6,TNF-α,IL-1β)were detected by ELISA,while oxidative stress markers(SOD,MDA,GSH)and tissue ferrous iron(Fe2+)levels were measured by colorimetric assays.Mitochondrial ultrastructure was observed via transmission electron microscopy(TEM).Nrf2,SLC7A11,and GPX4 expression in wound tissues were analyzed by qPCR and Western blot.In cell experiments,a high glucose(HG)-induced ferroptosis model in human umbilical vein endothelial cells(HUVECs)was established and divided into control,HG,CLY,and CLY combined with pathway inhibitors(ML385,Erastin,RSL3)groups.CCK-8 was used to detect cell via-bility,FerroOrange was used to detect Fe2+content,DCFH-DA and C11-BODIPY 581/591 probes were used to detect intracellular ROS and lipid ROS content,and Western blot was used to detect the expression of proteins such as Nrf2/SLC7A11/GPX4.RESULTS Animal experiments showed that compared with the model group,the wound healing rate in the low-and high-dose CLY groups was significantly improved(P<0.01);the serum IL-6,IL-1β,and TNF-α levels were significantly decreased(P<0.01);the MDA con-tent was significantly reduced(P<0.01),and the SOD activity and GSH content were significantly restored(P<0.05).Colorimetric a-nalysis showed that the low-and high-dose CLY significantly reduced the abnormally elevated Fe2+levels in DFU wounds(P<0.05,P<0.001).Electron microscopy showed that the mitochondrial cristae structure was improved in the low-and high-dose groups.qPCR showed that high-dose CLY upregulated the expression levels of Rno-Nfe2l2(Nrf2),Rno-Slc7a11,Rno-Gpx4,and Rno-Acsl4 mR-NA,and inhibited the expression level of Rno-Acsl4 mRNA(P<0.001).Western blot results showed that CLY upregulated the expres-sion of Nrf2,SLC7A11,GPX4,and FTH1 in DFU wound tissues(P<0.01),while downregulated the level of ACSL4(P<0.01).Cell experiments showed that treatment with CLY increased the survival rate of high glucose-stimulated HUVECs(P<0.001).However,the protective effect of CLY was significantly inhibited after the addition of ML385,Erastin,or RSL3(P<0.01).Treatment with CLY significantly decreased the Fe2+content(P<0.001),which was reversed by ML385,Erastin,or RSL3.The levels of ROS and lipid ROS were also significantly reduced(P<0.001),while the addition of ML385,Erastin,or RSL3 partially weakened the antioxidant effect of CLY.Western blot results showed that CLY significantly upregulated the expression of Nrf2、SLC7A11 and GPX4(P<0.001)and downregulated the expression of 4-HNE and COX2(P<0.01),and ML385,Erastin,or RSL3 could reverse this protective effect.CONCLUSION CLY promotes DFU healing by activating the Nrf2/SLC7A11/GPX4 pathway to inhibit ferroptosis,mitigate oxidative stress,and suppress inflammation,providing a novel therapeutic target for DFU.

OBJECTIVE To investigate the effects of Chuangling Ye(CLY)on diabetic foot ulcer(DFU)model mice based on the nuclear factor erythroid 2-related factor 2(Nrf2)/solute carrier family 7 member 11(SLC7A11)/glutathione peroxidase 4(GPX4)pathway and explore its potential mechanism.METHODS In animal experiments,streptozotocin(STZ)-induced diabetic mice with full-thickness skin defects were divided into control,model,positive control(recombinant human epidermal growth factor,rhEGF),and CLY low-and high-dose groups(n=10).After 14 days of intervention,wound healing rate was measured.Serum inflammatory factors(IL-6,TNF-α,IL-1β)were detected by ELISA,while oxidative stress markers(SOD,MDA,GSH)and tissue ferrous iron(Fe2+)levels were measured by colorimetric assays.Mitochondrial ultrastructure was observed via transmission electron microscopy(TEM).Nrf2,SLC7A11,and GPX4 expression in wound tissues were analyzed by qPCR and Western blot.In cell experiments,a high glucose(HG)-induced ferroptosis model in human umbilical vein endothelial cells(HUVECs)was established and divided into control,HG,CLY,and CLY combined with pathway inhibitors(ML385,Erastin,RSL3)groups.CCK-8 was used to detect cell via-bility,FerroOrange was used to detect Fe2+content,DCFH-DA and C11-BODIPY 581/591 probes were used to detect intracellular ROS and lipid ROS content,and Western blot was used to detect the expression of proteins such as Nrf2/SLC7A11/GPX4.RESULTS Animal experiments showed that compared with the model group,the wound healing rate in the low-and high-dose CLY groups was significantly improved(P<0.01);the serum IL-6,IL-1β,and TNF-α levels were significantly decreased(P<0.01);the MDA con-tent was significantly reduced(P<0.01),and the SOD activity and GSH content were significantly restored(P<0.05).Colorimetric a-nalysis showed that the low-and high-dose CLY significantly reduced the abnormally elevated Fe2+levels in DFU wounds(P<0.05,P<0.001).Electron microscopy showed that the mitochondrial cristae structure was improved in the low-and high-dose groups.qPCR showed that high-dose CLY upregulated the expression levels of Rno-Nfe2l2(Nrf2),Rno-Slc7a11,Rno-Gpx4,and Rno-Acsl4 mR-NA,and inhibited the expression level of Rno-Acsl4 mRNA(P<0.001).Western blot results showed that CLY upregulated the expres-sion of Nrf2,SLC7A11,GPX4,and FTH1 in DFU wound tissues(P<0.01),while downregulated the level of ACSL4(P<0.01).Cell experiments showed that treatment with CLY increased the survival rate of high glucose-stimulated HUVECs(P<0.001).However,the protective effect of CLY was significantly inhibited after the addition of ML385,Erastin,or RSL3(P<0.01).Treatment with CLY significantly decreased the Fe2+content(P<0.001),which was reversed by ML385,Erastin,or RSL3.The levels of ROS and lipid ROS were also significantly reduced(P<0.001),while the addition of ML385,Erastin,or RSL3 partially weakened the antioxidant effect of CLY.Western blot results showed that CLY significantly upregulated the expression of Nrf2、SLC7A11 and GPX4(P<0.001)and downregulated the expression of 4-HNE and COX2(P<0.01),and ML385,Erastin,or RSL3 could reverse this protective effect.CONCLUSION CLY promotes DFU healing by activating the Nrf2/SLC7A11/GPX4 pathway to inhibit ferroptosis,mitigate oxidative stress,and suppress inflammation,providing a novel therapeutic target for DFU.

Objective:To investigate the changes in hepatic phase II detoxification enzymes and their mechanism in metabolic associated steatohepatitis (MASH) induced by a methionine-choline-deficient (MCD) diet in mice.Methods:Ten C57BL/6J mice were randomly divided into two groups, with five mice in each group, and fed with a control diet (NCD group) and a methionine-choline-deficient diet (MCD group) for four consecutive weeks to establish the MASH model in mice. Mice body weight was recorded weekly. Mice peripheral blood and liver tissue samples were collected after four weeks. The liver histopathological changes were observed by hematoxylin-eosin staining and Sirius red staining in liver tissue. The levels of plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST) and triglycerides were measured by an automatic biochemical analyzer. Triglyceride and total cholesterol were used to evaluate the lipid accumulation condition in the liver of mice with Oil red O staining. Real-time fluorescence quantitative PCR was used to detect the expression of liver inflammatory factors interleukin (IL)-1β and monocyte chemoattractant protein-1 (MCP-1) condition. Transcriptome sequencing and bioinformatics were used to analyze the changes in gene expression profiles in the liver of mice and screen differentially expressed genes. The expression conditions of phase Ⅱ detoxification enzymes glutathione S-transferase mu 4 (GSTM4), dihydronicotinamide riboside:quinone oxidoreductases (NQO-2), sulfotransferase 1β1 (SULT1β1), and uridine diphosphate glucuronosyltransferase 2 family, polypeptide A3(UGT2A3) were verified by real-time fluorescent quantitative PCR. Plasma malondialdehyde content, total antioxidant capacity (T-AOC), plasma and liver glutathione content were determined using commercial kits. The expression of nuclear factor E2-related factor 2 (Nrf2), GSTM4, and UGT1A6 was examined by Western blotting. The independent sample t-test was used for comparison between the groups. Results:The body weight of mice in the MCD group showed a gradual downward trend, while the body weight of mice in the NCD group did not change significantly following four weeks of different dietary feeding. The MCD group mice liver had yellow-white appearance with round edges. The liver/body mass index was significantly lower in the NCD group ( t=3.216, P<0.01). Hematoxylin-eosin staining showed that hepatocytes in the MCD group had an occurrence of fatty degeneration accompanied by inflammatory cell infiltration, with a higher NAFLD activity score (NAS) compared to the NCD group ( t=7.155, P<0.001). Sirius red staining showed that the the liver of the MCD group had mildly increased periportal fibers. Plasma biochemical tests indicated that plasma ALT, AST, and triglyceride levels were significantly higher in the MCD group than those in the NCD group ( t=8.920, P<0.001; t=6.696, P<0.001; t=3.904, P<0.01). Oil red O staining showed that a large number of lipid droplets accumulated in the liver tissue of the MCD group and were more severe than those in the NCD group ( t=7.405, P<0.001). The triglyceride content was significantly higher in the liver of the mice in the MCD group than that in the NCD group ( t=3.559, P<0.01), and the expression of inflammatory factors IL-1β and MCP-1 was significantly increased ( t=2.562 and 2.391, respectively, P<0.05). Transcriptome sequencing analysis showed that the expression profile of genes related to lipid metabolism was changed in the liver tissue of the mice in the MCD group. The expression of multiple phase Ⅱ detoxification enzymes was significantly downregulated. Real-time fluorescence quantitative PCR verification demonstrated that the expression of four phase Ⅱ detoxification enzymes GSTM4, NQO2, SUIL1β1, and UGT2A3 were significantly lower in the liver of the mice in the MCD group than those in the NCD group ( t=2.498, 3.570, 3.768, and 4.166, respectively, P<0.05). The detection kit showed that compared with the NCD group, the malondialdehyde content in the liver of mice in the MCD group increased ( t=3.601, P<0.01), while the plasma total glutathione ( t=11.93, P<0.001) and reduced glutathione levels were significantly reduced ( t=3.635, P<0.01). The total antioxidant capacity of the liver decreased ( t=2.872, P<0.05), and the total glutathione and reduced glutathione levels in the liver were significantly increased ( t=3.175 and 3.064, P<0.05). Western blotting showed that the expression of Nrf2, GSTM4, and UGT1A6 proteins was significantly lower in the MCD group than that in the NCD group ( t=3.385, 2.990, 2.168, P<0.05). Conclusions:The expressions of multiple phase Ⅱ detoxification enzymes and antioxidant capacity are reduced in the liver of MASH mice induced by the MCD diet, and its mechanism is related to the down-regulation of the expression of the upstream regulatory factor Nrf2 protein.

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 report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-positive bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-positive bacteria from blood cultures in member hospitals of National Bloodstream Infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. 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 software were used to analyze the data.Results:A total of 3 163 strains of Gram-positive pathogens were collected from 51 member units，and the top five bacteria were Staphylococcus aureus（ n=1 147，36.3%），coagulase-negative Staphylococci（ n=928，29.3%）， Enterococcus faecalis（ n=369，11.7%）， Enterococcus faecium（ n=296，9.4%）and alpha-hemolyticus Streptococci（ n=192，6.1%）. The detection rates of methicillin-resistant Staphylococcus aureus（MRSA）and methicillin-resistant coagulase-negative Staphylococci（MRCNS）were 26.4%（303/1 147）and 66.7%（619/928），respectively. No glycopeptide and daptomycin-resistant Staphylococci were detected. The sensitivity rates of Staphylococcus aureus to cefpirome，rifampin，compound sulfamethoxazole，linezolid，minocycline and tigecycline were all >95.0%. Enterococcus faecium was more prevalent than Enterococcus faecalis. The resistance rates of Enterococcus faecium to vancomycin and teicoplanin were both 0.5%（2/369），and no vancomycin-resistant Enterococcus faecium was detected. The detection rate of MRSA in southern China was significantly lower than that in other regions（ χ2=14.578， P=0.002），while the detection rate of MRCNS in northern China was significantly higher than that in other regions（ χ2=15.195， P=0.002）. The detection rates of MRSA and MRCNS in provincial hospitals were higher than those in municipal hospitals（ χ2=13.519 and 12.136， P<0.001）. The detection rates of MRSA and MRCNS in economically more advanced regions（per capita GDP≥92 059 Yuan in 2022）were higher than those in economically less advanced regions（per capita GDP<92 059 Yuan）（ χ2=9.969 and 7.606， P=0.002和0.006）. Conclusions:Among the Gram-positive pathogens causing bloodstream infections in China， Staphylococci is the most common while the MRSA incidence decreases continuously with time；the detection rate of Enterococcus faecium exceeds that of Enterococcus faecalis. The overall prevalence of vancomycin-resistant Enterococci is still at a low level. The composition ratio of Gram-positive pathogens and resistant profiles varies slightly across regions of China，with the prevalence of MRSA and MRCNS being more pronounced in provincial hospitals and areas with a per capita GDP≥92 059 yuan.