Objective To investigate the correlation between the peripheral blood levels of long non-coding RNA urothelial carcinoma associated 1(lncRNA UCA1)and miR-665 with the occur-rence of coronary restenosis in patients with ACS after interventional treatment.Methods A total of 315 ACS patients admitted to the Affiliated Hospital of Hebei University from July 2022 to Ju-ly 2023 were recruited and then divided into occurrence group(62 cases)and non-occurrence group(253 cases)according to the occurrence of coronary restenosis.The expression of lncRNA UCA1 and miR-665 in peripheral blood samples was detected by real-time fluorescence quantita-tive PCR.Pearson analysis was applied to analyze the correlation between peripheral blood ln-cRNA UCA1 and miR-665 in ACS patients.Logistic regression analysis was used to identify the influencing factors for coronary restenosis in ACS patients.ROC curve was plotted to analyze the predictive value of peripheral blood lncRNA UCA1 and miR-665 for the restenosis,and their AUC values were calculated.Results The peripheral blood expression of lncRNA UCA1 was signifi-cantly higher,and that of miR-665 was obviously lower in the occurrence group than the non-occurrence group(1.28±0.22 vs 1.01±0.21,P=0.001;0.76±0.24 vs 1.01±0.22,P=0.001).Pearson analysis showed there was a negative correlation between miR-665 and lncRNA UCA1 expression levels in the ACS patients(r=-0.585,P＜0.05).Multivariate logistic regression anal-ysis indicated that LncRNA UCA1 was a risk factor(OR=2.124,95％CI:1.324-3.406,P=0.002),and miR-665 was a protective factor(OR=0.765,95％CI:0.653-0.897,P=0.001)for the occurrence of coronary restenosis in ACS patients after interventional treatment.ROC curve analysis revealed that the combination of peripheral blood lncRNA UCA1 and miR-665 had the highest AUC value in predicting the occurrence of coronary restenosis,which was better than the value of single molecule(Z=2.256,P=0.024;Z=2.904,P=0.004).Conclusion Combination of peripheral blood levels of lncRNA UCA1 and miR-665 has good performance for predicting coro-nary restenosis in ACS patients after interventional therapy.

Objective To investigate the effect and underlying mechanism of miR-137 on athero-sclerosis(AS)plaques in apolipoprotein E(ApoE)gene knockout(ApoE)mice.Methods Sixty ApoE-/-mice were fed with high-fat diet for 12 weeks to establish an AS model.Then they were assigned into AS group,negative control group,miR-137 group,Ad negative control group,and combination group,with 12 mice in each group;Another 12 wild-type C57BL/6 mice fed with chow diet were subjected as the Control group.Fully automated biochemical analyzer was applied to detect serum lipid levels,including total cholesterol(TC),triglycerides(TG),low-density lipo-protein cholesterol(LDL-C),and high-density lipoprotein cholesterol(HDL-C).ELISA was con-ducted to detect the levels of serum inflammatory factors,including TNF-α,IL-4,IL-6,and IL-10.HE staining was used to observe the morphological changes of mouse aortic tissue.Oil red O stai-ning was employed to observe the overall formation of aortic plaques.Immunofluorescence stai-ning was utilized to detect the expression of inducible nitric oxide synthase(iNOS)and arginase-1(Arg-1)in the aortic tissue.Real-time qPCR was applied to detect the mRNA expression of miR-137 and sex determining region Y box protein 4(SOX4)in the aorta.Results The miR-137 group has significantly lower serum levels of TG,TC,LDL-C,TNF-α and IL-6,and higher levels of HDL-C,IL-10 and IL-4 when compared with the AS group and negative control group(P＜0.05).The combination treatment resulted in increased serum levels of TG,TC,LDL-C,TNF-αand IL-6,while decreased levels of HDL-C,IL-10 and IL-4 in comparison with the Ad negative control group(P＜0.05).Larger aortic plaque area,more severe overall aortic plaque injury and stronger iNOS fluorescence intensity were observed in the AS group than the control group(P＜0.05).Treatment of miR-137 reversed above histological changes,resulting in smaller aortic plaque area,attenuated overall aortic plaque injury,decreased iNOS fluorescence intensity,and elevated Arg-1 fluorescence intensity when compared with the AS group and negative control group(P＜0.05).Compared with the Ad negative control group,the aortic plaque area,overall aortic plaque injury and iNOS fluorescence intensity were increased,while the Arg-1 fluorescence intensity was significantly decreased in the combined group(P＜0.05).Double luciferase assay showed that the luciferase activity of SOX4-containing wild-type cells was significantly decreased after transfection of miR-137 mimics when compared with transfection of mimics negative control(0.37±0.05 vs 1.00±0.08,P＜0.05).Conclusion Overexpression of miR-137 inhibits the activa-tion of rat sarcoma/mitogen-activated protein kinase pathway probably by down-regulating SOX4 expression,and then suppress M1 macrophage polarization and promote M2 macrophage polariza-tion,reduces inflammatory response and the formation of AS plaques.

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 changes in sympathetic nerve activity after lower limb immobilization and the role of sympathetic nerve in regulating disuse atrophy of skeletal muscles.Methods:The experiment was divided into the following 3 parts: ① Twelve 8-week-old male C57 mice were randomly divided into a blank control group and a hind limb fixation group ( n=6). The blank control group received no intervention while the hind limb fixation group received splint fixation of the hind limbs for 2 weeks before the musculoskeletal multi-dimensional characterization was completed at the behavioral, pathological and molecular levels. ② Thirty-six 8-week-old male C57 mice were selected and randomly divided into a control group and 5 hind limb fixation groups (for 1, 3, 5, 7 and 14 days) ( n=6). The control group was fed normally until 14 days without any intervention while the 5 hind limb fixation groups were sampled after fixation for 1, 3, 5, 7 and 14 days, respectively. The level of norepinephrine in the serum and the expression level of tyrosine hydroxylase (TH), a marker of sympathetic nerve activity in the paraventricular nucleus of hypothalamus (PVN), were detected to observe the plasticity of sympathetic nerve activity. ③ Eighteen 8-week-old male C57 mice were selected and randomly divided into a blank control group, a hind limb fixation group and a hind limb fixation plus medication group ( n=6). The blank control group received no intervention while the 2 fixation groups were injected with phosphate buffer (PBS) and propranolol hydrochloride solution for 2 consecutive weeks, respectively. The parameters related to the skeletal muscles were compared between the 3 groups. Results:① Compared with the control group, the mass and function of skeletal muscles in the hind limb fixation group were statistically significantly decreased ( P<0.05). ② The levels of serum norepinephrine [(3.27±1.03) ng/mL, (9.21±1.05) ng/mL, (6.36±0.88) ng/mL, (3.84±1.00) ng/mL, and (3.91±0.75) ng/mL] and the PVN TH levels (42.00%±5.38%, 61.67%±5.57%, 55.82%±3.11%, 50.90%±2.53%, and 39.17%±9.07%) in the 5 hind limb fixation groups (for 1, 3, 5, 7 and 14 days) were significantly higher than those in the control group [(1.81±0.72)] ng/mL and 23.33%±5.50%] ( P<0.05). ③ The wet weight of the gastrocnemius muscle [(93.50±4.32) mg] and the cross-section area of the tibial anterior muscle [(1,180.00±95.09) μm 2] in the hind limb fixation plus medication group were increased significantly compared with those in the hind limb fixation group [(80.83±9.99) mg and (907.80±121.00) μm 2] ( P<0.05). Conclusions:Overactivation of the sympathetic nervous system occurs in the mice model of skeletal muscle disuse atrophy after hind limb fixation. Inhibition of sympathetic nerve activity may reduce the severity of skeletal muscle atrophy at the lower limbs.

Objective To investigate the correlation between the peripheral blood levels of long non-coding RNA urothelial carcinoma associated 1(lncRNA UCA1)and miR-665 with the occur-rence of coronary restenosis in patients with ACS after interventional treatment.Methods A total of 315 ACS patients admitted to the Affiliated Hospital of Hebei University from July 2022 to Ju-ly 2023 were recruited and then divided into occurrence group(62 cases)and non-occurrence group(253 cases)according to the occurrence of coronary restenosis.The expression of lncRNA UCA1 and miR-665 in peripheral blood samples was detected by real-time fluorescence quantita-tive PCR.Pearson analysis was applied to analyze the correlation between peripheral blood ln-cRNA UCA1 and miR-665 in ACS patients.Logistic regression analysis was used to identify the influencing factors for coronary restenosis in ACS patients.ROC curve was plotted to analyze the predictive value of peripheral blood lncRNA UCA1 and miR-665 for the restenosis,and their AUC values were calculated.Results The peripheral blood expression of lncRNA UCA1 was signifi-cantly higher,and that of miR-665 was obviously lower in the occurrence group than the non-occurrence group(1.28±0.22 vs 1.01±0.21,P=0.001;0.76±0.24 vs 1.01±0.22,P=0.001).Pearson analysis showed there was a negative correlation between miR-665 and lncRNA UCA1 expression levels in the ACS patients(r=-0.585,P＜0.05).Multivariate logistic regression anal-ysis indicated that LncRNA UCA1 was a risk factor(OR=2.124,95％CI:1.324-3.406,P=0.002),and miR-665 was a protective factor(OR=0.765,95％CI:0.653-0.897,P=0.001)for the occurrence of coronary restenosis in ACS patients after interventional treatment.ROC curve analysis revealed that the combination of peripheral blood lncRNA UCA1 and miR-665 had the highest AUC value in predicting the occurrence of coronary restenosis,which was better than the value of single molecule(Z=2.256,P=0.024;Z=2.904,P=0.004).Conclusion Combination of peripheral blood levels of lncRNA UCA1 and miR-665 has good performance for predicting coro-nary restenosis in ACS patients after interventional therapy.

Objective To investigate the effect and underlying mechanism of miR-137 on athero-sclerosis(AS)plaques in apolipoprotein E(ApoE)gene knockout(ApoE)mice.Methods Sixty ApoE-/-mice were fed with high-fat diet for 12 weeks to establish an AS model.Then they were assigned into AS group,negative control group,miR-137 group,Ad negative control group,and combination group,with 12 mice in each group;Another 12 wild-type C57BL/6 mice fed with chow diet were subjected as the Control group.Fully automated biochemical analyzer was applied to detect serum lipid levels,including total cholesterol(TC),triglycerides(TG),low-density lipo-protein cholesterol(LDL-C),and high-density lipoprotein cholesterol(HDL-C).ELISA was con-ducted to detect the levels of serum inflammatory factors,including TNF-α,IL-4,IL-6,and IL-10.HE staining was used to observe the morphological changes of mouse aortic tissue.Oil red O stai-ning was employed to observe the overall formation of aortic plaques.Immunofluorescence stai-ning was utilized to detect the expression of inducible nitric oxide synthase(iNOS)and arginase-1(Arg-1)in the aortic tissue.Real-time qPCR was applied to detect the mRNA expression of miR-137 and sex determining region Y box protein 4(SOX4)in the aorta.Results The miR-137 group has significantly lower serum levels of TG,TC,LDL-C,TNF-α and IL-6,and higher levels of HDL-C,IL-10 and IL-4 when compared with the AS group and negative control group(P＜0.05).The combination treatment resulted in increased serum levels of TG,TC,LDL-C,TNF-αand IL-6,while decreased levels of HDL-C,IL-10 and IL-4 in comparison with the Ad negative control group(P＜0.05).Larger aortic plaque area,more severe overall aortic plaque injury and stronger iNOS fluorescence intensity were observed in the AS group than the control group(P＜0.05).Treatment of miR-137 reversed above histological changes,resulting in smaller aortic plaque area,attenuated overall aortic plaque injury,decreased iNOS fluorescence intensity,and elevated Arg-1 fluorescence intensity when compared with the AS group and negative control group(P＜0.05).Compared with the Ad negative control group,the aortic plaque area,overall aortic plaque injury and iNOS fluorescence intensity were increased,while the Arg-1 fluorescence intensity was significantly decreased in the combined group(P＜0.05).Double luciferase assay showed that the luciferase activity of SOX4-containing wild-type cells was significantly decreased after transfection of miR-137 mimics when compared with transfection of mimics negative control(0.37±0.05 vs 1.00±0.08,P＜0.05).Conclusion Overexpression of miR-137 inhibits the activa-tion of rat sarcoma/mitogen-activated protein kinase pathway probably by down-regulating SOX4 expression,and then suppress M1 macrophage polarization and promote M2 macrophage polariza-tion,reduces inflammatory response and the formation of AS plaques.

Objective:To investigate the changes in sympathetic nerve activity after lower limb immobilization and the role of sympathetic nerve in regulating disuse atrophy of skeletal muscles.Methods:The experiment was divided into the following 3 parts: ① Twelve 8-week-old male C57 mice were randomly divided into a blank control group and a hind limb fixation group ( n=6). The blank control group received no intervention while the hind limb fixation group received splint fixation of the hind limbs for 2 weeks before the musculoskeletal multi-dimensional characterization was completed at the behavioral, pathological and molecular levels. ② Thirty-six 8-week-old male C57 mice were selected and randomly divided into a control group and 5 hind limb fixation groups (for 1, 3, 5, 7 and 14 days) ( n=6). The control group was fed normally until 14 days without any intervention while the 5 hind limb fixation groups were sampled after fixation for 1, 3, 5, 7 and 14 days, respectively. The level of norepinephrine in the serum and the expression level of tyrosine hydroxylase (TH), a marker of sympathetic nerve activity in the paraventricular nucleus of hypothalamus (PVN), were detected to observe the plasticity of sympathetic nerve activity. ③ Eighteen 8-week-old male C57 mice were selected and randomly divided into a blank control group, a hind limb fixation group and a hind limb fixation plus medication group ( n=6). The blank control group received no intervention while the 2 fixation groups were injected with phosphate buffer (PBS) and propranolol hydrochloride solution for 2 consecutive weeks, respectively. The parameters related to the skeletal muscles were compared between the 3 groups. Results:① Compared with the control group, the mass and function of skeletal muscles in the hind limb fixation group were statistically significantly decreased ( P<0.05). ② The levels of serum norepinephrine [(3.27±1.03) ng/mL, (9.21±1.05) ng/mL, (6.36±0.88) ng/mL, (3.84±1.00) ng/mL, and (3.91±0.75) ng/mL] and the PVN TH levels (42.00%±5.38%, 61.67%±5.57%, 55.82%±3.11%, 50.90%±2.53%, and 39.17%±9.07%) in the 5 hind limb fixation groups (for 1, 3, 5, 7 and 14 days) were significantly higher than those in the control group [(1.81±0.72)] ng/mL and 23.33%±5.50%] ( P<0.05). ③ The wet weight of the gastrocnemius muscle [(93.50±4.32) mg] and the cross-section area of the tibial anterior muscle [(1,180.00±95.09) μm 2] in the hind limb fixation plus medication group were increased significantly compared with those in the hind limb fixation group [(80.83±9.99) mg and (907.80±121.00) μm 2] ( P<0.05). Conclusions:Overactivation of the sympathetic nervous system occurs in the mice model of skeletal muscle disuse atrophy after hind limb fixation. Inhibition of sympathetic nerve activity may reduce the severity of skeletal muscle atrophy at the lower limbs.

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.