This study aimed to explore the interaction between the small molecule Lyb24 and PyrD, a key enzyme in the pyrimidine biosynthesis pathway of Klebsiella pneumoniae (KP), and the effect of Lyb24 on the catalytic activity of PyrD, thus to provide a theoretical basis for the development of novel antimicrobial agents. The pET-30a(+)-PyrD recombinant plasmid was constructed using Nde I/Xba I double digestion technology and was transformed into Escherichia coli BL21 (DE3) competent cells using the heat-shock method. The recombinant protein was induced at 16 ℃ with 0.3 mmol/L isopropyl β-D-thiogalactopyranoside (IPTG). The recombinant PyrD protein was purified using nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography to obtain a high-purity product. Surface plasmon resonance (SPR) experiments were conducted to detect the direct interaction between Lyb24 and PyrD protein, and a DCIP-based colorimetric assay was used to evaluate the effect of Lyb24 on the catalytic activity of PyrD. The pET-30a(+)-PyrD plasmid was successfully constructed, and the recombinant PyrD protein with a molecular weight of approximately 36 kD was expressed and purified to a concentration of 5.58 mg/mL. Lyb24 exhibited high-affinity direct binding to PyrD (KD = 8.83 × 10−5 mol/L) and exerted an uncompetitive inhibition effect on the catalytic activity of PyrD. This study demonstrates that Lyb24, a small-molecule compound, directly binds to PyrD and inhibits its enzymatic activity, providing crucial experimental evidence for developing PyrD-targeted antibacterial agents with value of clinical translation.

OBJECTIVE To explore the mechanism of the active ingredient compatibility（quercetin， quercitrin and kaempferol at a mass ratio of 2∶9∶3）of Dimocarpus longan Lour. leaves（abbreviated as CDL） on ameliorating glucose and lipid metabolism disorders in type 2 diabetes mellitus （T2DM） rats. METHODS SD rats were randomly divided into blank control group， model group， metformin hydrochloride group （100 mg/kg）， and CDL high-， medium- and low-dose groups （280， 140， 75 mg/kg）， with 10 rats in each group. Rats in the blank control group were fed with standard chow， while rats in the other groups were given high-sugar and high-fat diet combined with intraperitoneal injection of streptozotocin to establish the T2DM rat model. After successful modeling， rats in each administration group were given corresponding drug solution， and rats in the blank control group and model group were intragastrically administered with equal volume of pure water， once a day， for consecutive 4 weeks. Fasting blood glucose （FBG） was detected at fixed time every week. The curves of oral glucose tolerance test （OGTT） and intraperitoneal insulin tolerance test （IPITT） were plotted， and the area under curve （AUC） was calculated. The pancreatic islet function indexes [fasting insulin （FINS）， homeostasis model assessment of insulin resistance （HOMA-IR）， insulin sensitivity index （ISI）]，blood lipid indexes [total cholesterol （TC）， triglyceride （TG）， low-density lipoprotein cholesterol （LDL-C）， high-density lipoprotein cholesterol （HDL-C）] and hepatic glycogen content were determined. The pathological morphological changes of liver and pancreatic tissues were observed. The protein and mRNA expression levels of molecules related to phosphatidylinositol 3-kinase （PI3K）/protein kinase B （Akt） signaling pathway in liver tissues were detected. RESULTS Compared with the blank control group， the FBG， AUC of IPITT curve， AUC of OGTT curve， HOMA-IR， the levels of FINS， TC， TG and LDL-C， as well as the protein and mRNA expression of phosphatase and tensin homolog， forkhead box protein O1 and glycogen synthase kinase-3β in liver tissues were significantly increased in the model group （ P ＜0.05）. ISI， the levels of HDL-C and hepatic glycogen content， along with the protein and mRNA expression of PI3K， insulin receptor substrate-1， Akt and protein expression of phosphorylated Akt in liver tissues were markedly decreased （ P ＜0.05）. In model group rats， the arrangement of hepatocytes was irregular， the overall structure of pancreatic lobules was disordered， and a large number of inflammatory cell infiltration was observed. Compared with the model group， most of the above quantitative indexes were significantly reversed in the CDL high-dose group （ P ＜0.05）， and the pathological lesions of liver and pancreas were obviously alleviated. CONCLUSIONS CDL can regulate glucose and lipid metabolism disorders， elevate insulin sensitivity and relieve insulin resistance in T2DM rats. Its mechanism may be related to the activation of the PI3K/Akt signaling pathway.

OBJECTIVE To explore the mechanism of the active ingredient compatibility（quercetin， quercitrin and kaempferol at a mass ratio of 2∶9∶3）of Dimocarpus longan Lour. leaves（abbreviated as CDL） on ameliorating glucose and lipid metabolism disorders in type 2 diabetes mellitus （T2DM） rats. METHODS SD rats were randomly divided into blank control group， model group， metformin hydrochloride group （100 mg/kg）， and CDL high-， medium- and low-dose groups （280， 140， 75 mg/kg）， with 10 rats in each group. Rats in the blank control group were fed with standard chow， while rats in the other groups were given high-sugar and high-fat diet combined with intraperitoneal injection of streptozotocin to establish the T2DM rat model. After successful modeling， rats in each administration group were given corresponding drug solution， and rats in the blank control group and model group were intragastrically administered with equal volume of pure water， once a day， for consecutive 4 weeks. Fasting blood glucose （FBG） was detected at fixed time every week. The curves of oral glucose tolerance test （OGTT） and intraperitoneal insulin tolerance test （IPITT） were plotted， and the area under curve （AUC） was calculated. The pancreatic islet function indexes [fasting insulin （FINS）， homeostasis model assessment of insulin resistance （HOMA-IR）， insulin sensitivity index （ISI）]，blood lipid indexes [total cholesterol （TC）， triglyceride （TG）， low-density lipoprotein cholesterol （LDL-C）， high-density lipoprotein cholesterol （HDL-C）] and hepatic glycogen content were determined. The pathological morphological changes of liver and pancreatic tissues were observed. The protein and mRNA expression levels of molecules related to phosphatidylinositol 3-kinase （PI3K）/protein kinase B （Akt） signaling pathway in liver tissues were detected. RESULTS Compared with the blank control group， the FBG， AUC of IPITT curve， AUC of OGTT curve， HOMA-IR， the levels of FINS， TC， TG and LDL-C， as well as the protein and mRNA expression of phosphatase and tensin homolog， forkhead box protein O1 and glycogen synthase kinase-3β in liver tissues were significantly increased in the model group （ P ＜0.05）. ISI， the levels of HDL-C and hepatic glycogen content， along with the protein and mRNA expression of PI3K， insulin receptor substrate-1， Akt and protein expression of phosphorylated Akt in liver tissues were markedly decreased （ P ＜0.05）. In model group rats， the arrangement of hepatocytes was irregular， the overall structure of pancreatic lobules was disordered， and a large number of inflammatory cell infiltration was observed. Compared with the model group， most of the above quantitative indexes were significantly reversed in the CDL high-dose group （ P ＜0.05）， and the pathological lesions of liver and pancreas were obviously alleviated. CONCLUSIONS CDL can regulate glucose and lipid metabolism disorders， elevate insulin sensitivity and relieve insulin resistance in T2DM rats. Its mechanism may be related to the activation of the PI3K/Akt signaling pathway.

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 cardiac protective effect of Taohong Tongluo granules on coronary microvascular dysfunction(CMD)rats.Methods SD rats were randomly assigned to sham-operated group,CMD group,nicorandil group(5 mg/kg),or Taohong Tongluo granule group(50 mg/kg).Animals were administered corresponding drugs for 7 d according to the grouping,and the CMD model was prepared 2 h after the last administration.The rat CMD model was induced by injecting embolization microspheres(diameter 40-120 μm,approximately 1 000 microspheres)into the left ventricular cavity.Twenty-four hours after modeling,echocardiography was performed to measure the left ventricular ejection fraction(EF),fractional shortening(FS),and end-diastolic volume(EDV).The damaged myocardial area was assessed by 2,3,5-triphenyltetrazolium chloride(TTC)staining.Myocardial morphological changes were observed by hematoxylin-eosin(H-E)staining.The protein expression levels of NOD-like receptor family pyrin domain containing protein 3(NLRP3),apoptosis-associated speck-like protein(ASC),and cysteine aspartic acid specific protease(caspase)-1 in rat myocardial tissue were detected by immunohistochemical staining and Western blotting.Results Echocardiography showed that the EF and FS values in the Taohong Tongluo granule group,CMD group,and nicorandil group were significantly lower than those in the sham-operated group(all P＜0.001).The EF and FS values in the Taohong Tongluo granule group and nicorandil group were significantly higher than those in the CMD group(all P＜0.01).However,there were no significant differences in EDV among the groups(all P＞0.05).H-E staining showed no abnormalities in the myocardium in the sham-operated group.The CMD group exhibited microsphere embolism in the myocardium,myocardial cell dissolution and rupture,and inflammatory infiltration.The lesions in the nicorandil group and the Taohong Tongluo granule group were relatively milder,and the number of thrombi in both groups was lower than that in the CMD group(both P＜0.01).The results of TTC staining indicated that the areas of damaged myocardial regions in both the nicorandil group and the Taohong Tongluo granule group were smaller than that in the CMD group(P＜0.05 or P＜0.01).Moreover,the area in the Taohong Tongluo granule group was smaller than that in the nicorandil group(P＜0.05).The results of immunohistochemical staining showed that in the CMD model,the expression of ASC and caspase-1 proteins,as well as the number of positive cells for these proteins,was increased and was distributed in myocardial and interstitial cells.The numbers of ASC and caspase-1 positive cells in the Taohong Tongluo granule group were lower than that in the CMD group(both P＜0.01).The Western blotting showed that the expression levels of NLRP3,ASC,and caspase-1 proteins in the Taohong Tongluo granule group were all lower than those in the CMD group(all P＜0.05).Conclusion Taohong Tongluo granules can improve cardiac function,ameliorate hemodynamic parameters,and reduce myocardial infarction area in rats with CMD induced by microsphere embolism.The mechanism is related to the inhibition of myocardial inflammasome activation,thereby attenuating the myocardial injuries.

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 pathogen distribution and prognostic risk factors of catheter-related bloodstream infection (CRBSI) in patients with maintenance hemodialysis (MHD) during non-hospitalization.Methods:A retrospective comparative study was conducted. Thirty-four patients of MHD with semi-permanent catheter admitted to the department of nephrology of Gansu Provincial Hospital from January 2020 to May 2023 due to CRBSI during non-hospitalization were enrolled. The distribution characteristics of pathogens causing CRBSI in MHD patients during non-hospital period were analyzed. All patients were actively given anti-infection treatment after admission. The general data, laboratory indicators and prognosis during hospitalization were collected through the electronic medical record system. Patients were divided into poor prognosis group (14 cases) and good prognosis group (20 cases) according to the treatment results during hospitalization. Univariate and binary Logistic regression were used to analyze the risk factors affecting the prognosis of patients, and receiver operator characteristic curve (ROC curve) was drawn to evaluate its predictive value for prognosis.Results:A total of 28 pathogenic bacteria were isolated from 34 patients, of which 25 were Gram-positive, Staphylococcus was the most common pathogen, accounting for 82.15% of the total, and 16 strains of Staphylococcus aureus (57.15%), including 6 methicillin-resistant Staphylococcus aureus (MRSA, 21.43%). There were 7 strains of Staphylococcus epidermidis (25.00%), including 3 strains of methicillin-resistant Staphylococcus epidermidis (MRSE, 10.71%). There were 3 strains of Gram-negative bacteria, 1 strain each of Pseudomonas aeruginosa, Escherichia coli and Acinetobacter baumannii. Univariate analysis showed that the fever duration of MHD patients with CRBSI in the poor prognosis group was significantly longer than that in the good prognosis group [days: 8.50 (3.75, 45.00) vs. 2.50 (1.00, 4.75), P < 0.01], serum erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and random blood glucose (GLU) were significantly higher than those in the good prognosis group [ESR (mm/1 h): 82.36±24.98 vs. 56.95±35.65, CRP (mg/L): 123.45±74.10 vs. 67.35±55.22, GLU (mmol/L): 8.74±3.66 vs. 6.42±1.95, all P < 0.05]. Binary Logistic regression analysis showed that serum CRP was an independent risk factor for poor prognosis in MHD patients with CRBSI [odds ratio ( OR) = 1.020, 95% confidence interval (95% CI) was 1.002-1.038, P = 0.025]. ROC curve analysis showed that the area under the curve (AUC) of serum CRP in predicting poor prognosis of MHD patients with CRBSI was 0.711; when the optimal cut-off value was 104.65 mg/L, the sensitivity was 64.3% and the specificity was 85.0%, indicating that it has good predictive value. Conclusions:Gram-positive bacteria are the main pathogens of CRBSI in MHD patients during non-hospital period. The poor prognosis is mainly related to the high level of serum CRP. Serum CRP level can effectively screen the high-risk group of MHD patients with CRBSI with poor prognosis.

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.