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 analyze the risk factors for meconium-stained amniotic fluid(MSAF)in preterm infants and the clinical outcome and prognosis of preterm infants.Methods Preterm infants with gestational age＜37 weeks delivered in Zhangjiajie People's Hospital from January 2022 to December 2023 were used as the study subjects,31 cases with MSAF were in MSAF group,and 31 cases of preterm infants hospitalized during the same period without MSAF were randomly paired in the ratio of 1∶1 to select with gestational age-body mass matching as non-MSAF group.Retrospective collection and analysis of pregnancy and perinatal conditions of mothers of preterm infants in two groups,comparing the differences of related factors between two groups of children;Logistic regression analysis of risk factors related to MSAF in preterm infants;comparing the complications and clinical outcomes of preterm infants in two groups.Results A total of 387 preterm infants with gestational age＜37 weeks were collected during the study period,including 31 preterm infants with comorbid MSAF,and the prevalence of MSAF in preterm infants was 8.0％.MSAF group had a higher incidence of advanced maternal age,premature rupture of membranes＞18 hours,antepartum fever,and cholestasis during pregnancy than non-MSAF group.Logistic regression analysis suggested that combined cholestasis during pregnancy and white blood cell count ≥ 30× 109/L within 6 hours after birth increased the incidence of MSAF in preterm infants.There was no statistically significant difference in the results of postnatal umbilical artery blood gas analysis between two groups of preterm infants.The proportion of leukocyte count ≥30×109/L,ultrasensitive C-reactive protein＞0.8 mg/L,and interleukin 6＞6 pg/L in MSAF group was higher than that of non-MSAF group in the 6 hours after birth.MSAF group had a higher incidence of intrauterine infectious pneumonia,feeding intolerance,and necrotizing small bowel colitis in neonates than non-MSAF group.Conclusion Advanced maternal age,intrauterine infections,and combined intrahepatic cholestasis during pregnancy may be the major risk factors for MSAF in preterm infants.MSAF preterm infants have a higher prevalence of intrauterine infectious pneumonitis,feeding intolerance,and necrotizing small bowel colitis in newborns,as well as longer hospital stays.

Objective To investigate the mechanism by which 4-week high-intensity interval training(HIIT)regulates the mitochondrial unfolded protein response(UPRmt)in skeletal muscle and improves mitochondrial function in a rat model of chronic unpredictable mild stress(CUMS).Methods Male SPF-grade SD rats(6～8 weeks old)were divided randomly into control(C),model(M),HIIT+control(HC),and HIIT+model(HM)groups.Rats in the M and HM groups were subjected to CUMS for 8 weeks to establish a depression model,while rats in the HC and HM groups received HIIT for 5 d a week for 4 weeks.The exercise regimen consisted of 3 min high-speed(85％～90％Smax)combined with 1 min low-speed(50％～55％Smax)uninterrupted repetitive training(Smax is maximum training speed).Behavioral changes were evaluated at weeks 4 and 8.Tissue samples were taken 24 h after the last behavioral test and skeletal muscle mitochondria were examined by transmission electron microscopy.The ATP and reactive oxygen species(ROS)contents were measured by enzyme-linked immunosorbent assays and protein expression levels of activating transcription factor(ATF)4,ATF5,C/EBP homologous protein(CHOP),and heat shock protein 60(HSP60)were detected by Western blot.Results(1)The body mass,number of crossing grids,number of upright positions,sugar-water preference rate,and ATP content were significantly decreased in group M compared with group C(P＜0.01),while the number of damaged mitochondria,ROS content,ATF4,ATF5,CHOP,and HSP60 protein expression were significantly increased(P＜0.01).(2)After 4-weeks of HIIT intervention,the ATP content and ATF4 and ATF5 protein expression levels were significantly increased in the HC group compared with C group(P＜0.05,P＜0.01).The number of crossing grids,number of upright positions,sugar-water preference rate,ATP content,and ATF4 protein expression were significantly increased in the HM group compared with M group(P＜0.01),while the number of damaged mitochondria,ROS content,and ATF5,CHOP,and HSP60 protein expression levels were significantly decreased(P＜0.01).(3)After 4 weeks of HIIT intervention,the number of crossing grids in CUMS rats was significantly positively correlated with ATF4 protein expression,and ROS content was correlated with CHOP protein expression,number of damaged mitochondria,and ATF5 protein expression(|r|＞0.75,P＜0.01;|r|＞0.75,P＜0.05).Upright frequency was significantly negatively correlated with ATF5 and HSP60 protein expression,the number of crossing grids,the sugar-water preference rate,and the expression of CHOP and HSP60 proteins(|r|＜0.75,P＜0.05).Conclusions 4-week HIIT intervention can improve mitochondrial dysfunction and alleviate depressive-like behavior in CUMS rats by regulating skeletal muscle UPRmt.

Objective To investigate the mechanism by which 4-week high-intensity interval training(HIIT)regulates the mitochondrial unfolded protein response(UPRmt)in skeletal muscle and improves mitochondrial function in a rat model of chronic unpredictable mild stress(CUMS).Methods Male SPF-grade SD rats(6～8 weeks old)were divided randomly into control(C),model(M),HIIT+control(HC),and HIIT+model(HM)groups.Rats in the M and HM groups were subjected to CUMS for 8 weeks to establish a depression model,while rats in the HC and HM groups received HIIT for 5 d a week for 4 weeks.The exercise regimen consisted of 3 min high-speed(85％～90％Smax)combined with 1 min low-speed(50％～55％Smax)uninterrupted repetitive training(Smax is maximum training speed).Behavioral changes were evaluated at weeks 4 and 8.Tissue samples were taken 24 h after the last behavioral test and skeletal muscle mitochondria were examined by transmission electron microscopy.The ATP and reactive oxygen species(ROS)contents were measured by enzyme-linked immunosorbent assays and protein expression levels of activating transcription factor(ATF)4,ATF5,C/EBP homologous protein(CHOP),and heat shock protein 60(HSP60)were detected by Western blot.Results(1)The body mass,number of crossing grids,number of upright positions,sugar-water preference rate,and ATP content were significantly decreased in group M compared with group C(P＜0.01),while the number of damaged mitochondria,ROS content,ATF4,ATF5,CHOP,and HSP60 protein expression were significantly increased(P＜0.01).(2)After 4-weeks of HIIT intervention,the ATP content and ATF4 and ATF5 protein expression levels were significantly increased in the HC group compared with C group(P＜0.05,P＜0.01).The number of crossing grids,number of upright positions,sugar-water preference rate,ATP content,and ATF4 protein expression were significantly increased in the HM group compared with M group(P＜0.01),while the number of damaged mitochondria,ROS content,and ATF5,CHOP,and HSP60 protein expression levels were significantly decreased(P＜0.01).(3)After 4 weeks of HIIT intervention,the number of crossing grids in CUMS rats was significantly positively correlated with ATF4 protein expression,and ROS content was correlated with CHOP protein expression,number of damaged mitochondria,and ATF5 protein expression(|r|＞0.75,P＜0.01;|r|＞0.75,P＜0.05).Upright frequency was significantly negatively correlated with ATF5 and HSP60 protein expression,the number of crossing grids,the sugar-water preference rate,and the expression of CHOP and HSP60 proteins(|r|＜0.75,P＜0.05).Conclusions 4-week HIIT intervention can improve mitochondrial dysfunction and alleviate depressive-like behavior in CUMS rats by regulating skeletal muscle UPRmt.

Objective To analyze the risk factors for meconium-stained amniotic fluid(MSAF)in preterm infants and the clinical outcome and prognosis of preterm infants.Methods Preterm infants with gestational age＜37 weeks delivered in Zhangjiajie People's Hospital from January 2022 to December 2023 were used as the study subjects,31 cases with MSAF were in MSAF group,and 31 cases of preterm infants hospitalized during the same period without MSAF were randomly paired in the ratio of 1∶1 to select with gestational age-body mass matching as non-MSAF group.Retrospective collection and analysis of pregnancy and perinatal conditions of mothers of preterm infants in two groups,comparing the differences of related factors between two groups of children;Logistic regression analysis of risk factors related to MSAF in preterm infants;comparing the complications and clinical outcomes of preterm infants in two groups.Results A total of 387 preterm infants with gestational age＜37 weeks were collected during the study period,including 31 preterm infants with comorbid MSAF,and the prevalence of MSAF in preterm infants was 8.0％.MSAF group had a higher incidence of advanced maternal age,premature rupture of membranes＞18 hours,antepartum fever,and cholestasis during pregnancy than non-MSAF group.Logistic regression analysis suggested that combined cholestasis during pregnancy and white blood cell count ≥ 30× 109/L within 6 hours after birth increased the incidence of MSAF in preterm infants.There was no statistically significant difference in the results of postnatal umbilical artery blood gas analysis between two groups of preterm infants.The proportion of leukocyte count ≥30×109/L,ultrasensitive C-reactive protein＞0.8 mg/L,and interleukin 6＞6 pg/L in MSAF group was higher than that of non-MSAF group in the 6 hours after birth.MSAF group had a higher incidence of intrauterine infectious pneumonia,feeding intolerance,and necrotizing small bowel colitis in neonates than non-MSAF group.Conclusion Advanced maternal age,intrauterine infections,and combined intrahepatic cholestasis during pregnancy may be the major risk factors for MSAF in preterm infants.MSAF preterm infants have a higher prevalence of intrauterine infectious pneumonitis,feeding intolerance,and necrotizing small bowel colitis in newborns,as well as longer hospital stays.

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 incidence and risk factors of deep vein thrombosis(DVT)in patients with rheumatoid arthritis(RA).Methods:The clinical data of RA patients who were hospi-talized in the Department of Rheumatology and Immunology of Aerospace Center Hospital from May 2015 to September 2021 was retrospectively analyzed,including demographic characteristics,concomitant diseases,laboratory examinations(blood routine,biochemistry,coagulation,inflammatory markers,rheumatoid factor,antiphospholipid antibodies and lupus anticoagulant,etc.)and treatment regimens.The patients were compared according to the presence or absence of DVT,and the t test,Mann-Whitney U test or Chi-square test were applied to screen for relevant factors for DVT,followed by Logistic regres-sion analysis to determine risk factors for DVT in patients with RA.Results:The incidence of DVT in the RA patients was 9.6％(31/322);the median age of RA in DVT group was significantly older than that in non-DVT group[64(54,71)years vs.50(25,75)years,P＜0.001];the level of disease activity score using 28 joints(DAS28)-erythrocyte sedimentation rate(ESR)in DVT group was higher than that in non-DVT group[5.2(4.5,6.7)vs.4.5(4.5,5.0),P＜0.001];the incidence of hypertension,chronic kidney disease,fracture or surgery history within 3 months,and varicose veins of the lower ex-tremities in DVT group was higher than that in non-DVT group(P＜0.001).The levels of hemoglobin and albumin in DVT group were significantly lower than that in non-DVT group(P=0.009,P=0.004),while the D-dimer level and rheumatoid factor positive rate in DVT group were significantly higher than that in non-DVT group(P＜0.001).The use rate of glucocorticoid in DVT group was higher than that in non-DVT group(P=0.009).Logistic regression analysis showed that the age(OR=1.093,P＜0.001),chronic kidney disease(OR=7.955,P=0.005),fracture or surgery history with-in 3 months(OR=34.658,P=0.002),DAS28-ESR(OR=1.475,P=0.009),and the use of glu-cocorticoid(OR=5.916,P=0.003)were independent risk factors for DVT in RA patients.Conclu-sion:The incidence of DVT in hospitalized RA patients was significantly increased,in addition to tradi-tional factors,such as age and chronic kidney disease,increased DAS28-ESR level and the use of glu-cocorticoid were also independent risk factors for DVT.

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-negative 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:During the study period，9 035 strains of Gram-negative bacteria were collected from 51 hospitals，of which 7 895（87.4%）were Enterobacteriaceae and 1 140（12.6%）were non-fermenting bacteria. The top 5 bacterial species were Escherichia coli（ n=4 510，49.9%）， Klebsiella pneumoniae（ n=2 340，25.9%）， Pseudomonas aeruginosa（ n=534，5.9%）， Acinetobacter baumannii complex（ n=405，4.5%）and Enterobacter cloacae（ n=327，3.6%）. The ESBLs-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus spp. were 47.1%（2 095/4 452），21.0%（427/2 033）and 41.1%（58/141），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（58/4 510）and 13.1%（307/2 340）；62.1%（36/58）and 9.8%（30/307）of CREC and CRKP were resistant to ceftazidime/avibactam combination，respectively. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 59.5%（241/405），while less than 5% of Acinetobacter baumannii complex was resistant to tigecycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 18.4%（98/534）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of main Gram-negative bacteria resistance among different regions，with statistically significant differences in the prevalence of CRKP and CRPA（ χ2=20.489 and 20.252， P<0.001）. The prevalence of CREC，CRKP，CRPA，CRAB，ESBLs-producing Escherichia coli and Klebsiella pneumoniae were higher in provinicial hospitals than those in municipal hospitals（ χ2=11.953，81.183，10.404，5.915，12.415 and 6.459， P<0.01 or <0.05），while the prevalence of CRPA was higher in economically developed regions（per capita GDP ≥ 92 059 Yuan）than that in economically less-developed regions（per capita GDP <92 059 Yuan）（ χ2=6.240， P=0.012）. Conclusions:The proportion of Gram-negative bacteria in bloodstream infections shows an increasing trend，and Escherichia coli is ranked in the top，while the trend of CRKP decreases continuously with time. Decreasing trends are noted in ESBLs-producing Escherichia coli and Klebsiella pneumoniae. Low prevalence of carbapenem resistance in Escherichia coli and high prevalence in CRAB complex have been observed. The composition ratio and antibacterial spectrum of bloodstream infections in different regions of China are slightly different，and the proportion of main drug resistant bacteria in provincial hospitals is higher than those in municipal hospitals.