BACKGROUND:Cervical disc herniation can cause pain in the neck and shoulder area,as well as radiating pain in the upper limbs.The incidence rate is increasing year by year and tends to affect younger individuals.Fully understanding the biomechanical characteristics of the cervical spine in adolescents is of great significance for preventing and delaying the onset of cervical disc herniation in this age group. OBJECTIVE:To reconstruct cervical spine models for both healthy adolescents and adolescent patients with cervical disc herniation utilizing finite element analysis techniques,to analyze the motion range of the C1-T1 cervical vertebrae as well as the biomechanical characteristics of the annulus fibrosus,nucleus pulposus,endplates,and the cartilage of the small joints. METHODS:A normal adolescent's cervical spine and an adolescent patient with cervical disc herniation were selected in this study.The continuous scan cervical spine CT raw image data were imported into Mimics 21.0 in DICOM format.The C1-T1 vertebrae were reconstructed separately.Subsequently,the established models were imported into the 3-Matic software for disc reconstruction.The perfected models were then imported into Hypermesh software for meshing of the vertebrae,nucleus pulposus,annulus fibrosus,and ligaments,creating valid geometric models.After assigning material properties,the final models were imported into ABAQUS software to observe the joint motion range of the C1-C7 cervical vertebrae segments under different conditions,and to analyze the biomechanical characteristics of the annulus fibrosus,nucleus pulposus,endplates,and small joint cartilage of each cervical spine segment. RESULTS AND CONCLUSION:(1)In six different conditions,the joint motion range of the C1 vertebra in the cervical spine models of both normal adolescent and adolescent patient with cervical disc herniation was higher than that of the other vertebrae.Additionally,the joint motion range of each cervical spine segment in normal adolescent was greater than that in adolescent patient with cervical disc herniation.(2)In the cervical spine model of normal adolescent,the maximum stress values in the annulus fibrosus and nucleus pulposus were found on the left side during C2-3 flexion conditions(0.43 MPa and 0.17 MPa,respectively).In the cervical spine model of adolescent patient with cervical disc herniation,the maximum stress values were found on the left side during C7-T1 flexion conditions(0.54 MPa and 0.18 MPa,respectively).(3)In the cervical spine model of normal adolescent,the maximum stress value on the endplate was found on the left side of the upper endplate of C3 during flexion conditions(1.46 MPa).In the model of adolescent patient with cervical disc herniation,the maximum stress value on the endplate was found on the left side of the lower endplate of C7 during flexion conditions(1.32 MPa).(4)In the cervical spine model of normal adolescent,the maximum stress value in the small joint cartilage was found in the C2-3 left rotation conditions(0.98 MPa).In adolescent patient with cervical disc herniation,the stress in the small joint cartilage significantly increased under different conditions,especially in C1-2,with the maximum stress found during left flexion(3.50 MPa).(5)It is concluded that compared to normal adolescent,adolescent patient with cervical disc herniation exhibits altered cervical curvature and a decrease in overall joint motion range in the cervical spine.In adolescent with cervical disc herniation,there is a significant increase in stress on the annulus fibrosus,nucleus pulposus,and endplates in the C7-T1 segment.The stress on the left articular cartilage of the C1-2 is notable.Abnormal cervical curvature may be the primary factor causing these stress changes.

OBJECTIVE To predict and validate the potential mechanisms of Kaixinsan （KXS） in ameliorating neuroinflammation in Alzheimer’s disease （AD）. METHODS Network pharmacology was employed to identify core anti- inflammatory components and key inflammatory targets of KXS for AD. Gene ontology （GO） functional annotation， Kyoto Encyclopedia of Genes and Genomes （KEGG） pathway enrichment， and molecular docking were performed. Based on these findings， male SD rats were used to establish an AD model via chronic D-galactose induction. The effects of KXS on AD rats were evaluated， including quantitative behavioral score， learning and memory parameters （escape latency， platform crossings， platform quadrant distance and time）， organ indexes （heart， liver， spleen， thymus）， histopathological alterations in the hippocampus， and expressions of inflammation-related pathway proteins and their upstream/downstream regulators. RESULTS Core anti-inflammatory components of KXS for AD included gomisin B， panaxytriol， gomisin A， enhydrin， vulgarin and panaxydol， while key inflammatory targets involved nuclear factor-kappa B subunit 1（ NFKB1）， nuclear factor-κB p65（ NF-κB p65）， interleukin-1β（ IL- 1β）， IL-6， Toll-like receptor 4 （TLR4）， tumor necrosis factor， nucleotide-binding domain leucine-rich repeat and pyrin domain- containing receptor 3 （NLRP3） and caspase-1 （CASP1）. GO and KEGG pathway enrichment involved inflammatory response， phosphorylation and the NF-κB signaling pathway. Molecular docking confirmed strong binding affinities between core components and key targets. Animal experiments demonstrated that， compared to the model group， KXS significantly alleviated histopathological damage （e.g.， neuronal shrinkage， reduced Nissl bodies in hippocampal CA1， CA3， and DG regions）， increased organ indexes （except for liver index） and Nissl-stained positive cells， improved learning and memory performance， and reduced behavioral scores （at the 8 and 12 weeks of the experiment） and protein expression of NF- κB p65， phosphorylated NF- κB p65， TLR4， NLRP3， CASP1 and IL-1β. CONCLUSIONS KXS effectively mitigates neuroinflammation， reduces hippocampal neuronal injury， and enhances learning and memory ability in AD rats， potentially through suppressing the NF-κB signaling pathway and its upstream/ downstream regulators.

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.

Objective:To evaluate the influence of ankle acupuncture on the cognitive impairment caused by sevoflurane in elderly rats and the expression of hippocampal phosphorylated phospholipase Cγ (p-PLCγ).Methods:Fifteen SPF-grade healthy male Sprague-Dawley rats, aged 18 months, weighing 530-600 g, were allocated into 3 groups ( n=5 each) using a random number table method: sham surgery group (S group), cognitive dysfunction group (CD group) and ankle acupuncture group (A group). The cognitive dysfunction model was prepared by inhaling the mixture of 3% sevoflurane and air, with ankle acupuncture applied to the right hind limb 1-3 region for 30 min prior to anesthesia in A group. S group received sham stimulation. Two days later, the cognitive function was assessed using the Morris water maze test. The rats were subsequently sacrificed and hippocampal tissues were collected for microscopic examination of the pathological changes (using HE staining and Nissl staining) and for determination of the expression of p-PLCγ, phosphorylated calcium/calmodulin-dependent protein kinase Ⅱ (p-CaMKⅡ) and phosphorylated inositol-1, 4, 5-trisphosphate receptor (p-IP3R). Results:Compared with S group, the escape latency was significantly prolonged, the number of crossing the original platform quadrant was reduced, and the expression of p-PLCγ, p-CaMKII and p-IP3R was up-regulated in CD group and A group ( P<0.05). Compared with CD group, the escape latency was significantly shortened, the number of crossing the original platform quadrant was increased, and the expression of p-PLCγ, p-CaMKII and p-IP3R was down-regulated in A group ( P<0.05). The pathological changes were significantly reduced in A group compared with CD group. Conclusions:Ankle acupuncture can ameliorate cognitive dysfunction induced by sevoflurane in elderly rats, and the mechanism is related to inhibition of hippocampal p-PLCγ expression.

Objective To explore the pharmacodynamic substances of Simiao Wan for the treatment of hyperuricemia and gout.Methods The pharmacological model of hyperuricemia was established.The chemical components in vivo and in vitro of Simiao Wan were analyzed by UPLC-Q-Exactive-MS.Based on the components absorbed in blood,the"active ingredient-target-pathway"network of Simiao Wan for regulating hyperuricemia and gout was constructed by network pharmacology method.The key ingredients were used for molecular docking with key targets[uricogenase(XDH),uric acid transporter(ABCG2,GLUT9,OAT1,URAT1)and inflammatory targets(PTGS2,TLR2,TLR4)]of hyperuricemia and gout.Finally,experimental verification was conducted according to the results of molecular docking.Our aim is to identify the key pharmacodynamic substances of Simiao Wan for the treatment of hyperuricemia and gout.Results Eighty-nine components of Simiao Wan were identified by UPLC-Q-Exactive-MS analysis,including 74 components absorbed in blood,which were confirmed as candidate ingredients.Network pharmacology was used to constructed"components absorbed in blood-target-pathway"network,and components absorbed in blood were matched with 116 targets of hyperuricemia and 173 targets of gout.It is involved in the regulation of biological processes,such as glucose and lipid metabolism,oxidative stress,inflammatory response,ERK1 and ERK2 cascade,MAPK cascade,PI3K signal transduction.Moreover,Simiao Wan plays a role in regulating the network of hyperuricemia and gout through regulating blood lipids and atherosclerosis,apoptosis,AGE-RAGE,TNF,PI3K-Akt,MAPK,TLRs,JAK-STAT,NF-κB and other signaling pathways.Molecular docking studies showed that berberine,phellodendrine,magnoflorine,jatrorrhizine,palmatine,obacunone,limonin,atractylodin,taxifolin,atractylenolide Ⅲ and β-ecdysterone had good affinity with uric acid synthase,uric acid transporter and inflammatory targets.Western Blot test showed that taxifolin negatively regulates the expression of URAT1.The above-mentioned compounds were the main pharmacodynamic substances of Simiao Wan for the treatment of hyperuricemia and gout.Conclusion This article describes the main pharmacodynamic substances of Simiao Wan in the regulation of hyperuricemia and gout,which can provides a scientific basis for the clinical application,improvement in quality evaluation and standard of Simiao Wan.

Objective:To investigate the interactive effect of mismatch repair (MMR) protein status and adverse clinicopathological features on prognosis of stage Ⅰ-Ⅲ colon cancer.Methods:The retrospective cohort study was conducted. The clinicopathological data of 1 650 patients with colon cancer of stage Ⅰ-Ⅲ who were admitted to 7 hospitals in China from January 2016 to December 2017 were collected. There were 963 males and 687 females, aged 62(53,71)years. Patients were classified as 230 cases of MMR deficiency (dMMR) and 1 420 cases of MMR proficiency (pMMR) based on their MMR protein status. Observation indicators: (1) comparison of clinicopathological characteristics between patients of different MMR protein status; (2) analysis of factors affecting the survival outcomes of patients of dMMR; (3) analysis of factors affecting the survival outcomes of patients of pMMR; (4) interaction analysis of MMR and adverse clinicopathological features on survival outcomes. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was conducted using the independent t test. Measurement data with skewed distribution were represented as M( Q1, Q3), and comparison between groups was conducted using the Mann-Whitney U test. Count data were described as absolute numbers, and comparison between groups was conducted using the chi-square test or Fisher exact probability. Comparison of ordinal data was conducted using the Mann-Whitney U test. The random forest interpolation method was used for missing values in data interpolation. Univariate analysis was conducted using the COX proportional risk regression model, and multivariate analysis was conducted using the COX stepwise regression with forward method. The coefficient of multiplication interaction effect was obtained using the interaction term coefficient of COX proportional risk regression model. Evaluation of additive interaction effects was conducted using the relative excess risk due to interaction ( RERI). Results:(1) Comparison of clinicopathological characteristics between patients of different MMR protein status. There were significant differences in age, T staging, the number of lymph node harvest, the number of lymph node harvest <12, high grade tumor between patients of dMMR and pMMR ( P<0.05). (2) Analysis of factors affecting the survival outcomes of patients of dMMR. Results of multivariate analysis showed that T staging, N staging, the number of lymph node harvest <12 were independent factors affecting the disease-free survival (DFS) of colon cancer patients of dMMR ( hazard ratio=3.548, 2.589, 6.702, 95% confidence interval as 1.460-8.620, 1.064-6.301, 1.886-23.813, P<0.05). Age and N staging were independent factors affecting the overall survival (OS) of colon cancer patients of dMMR ( hazard ratio=1.073, 10.684, 95% confidence interval as 1.021-1.126, 2.311-49.404, P<0.05). (3) Analysis of factors affecting the survival outcomes of patients of pMMR. Results of multivariate analysis showed that age, T staging, N staging, vascular tumor thrombus were independent factors affecting the DFS of colon cancer patients of pMMR ( hazard ratio=1.018, 2.214, 2.598, 1.549, 95% confidence interval as 1.006-1.030, 1.618-3.030, 1.921-3.513, 1.118-2.147, P<0.05). Age, T staging, N staging, high grade tumor were independent factors affecting the OS of colon cancer patients of pMMR ( hazard ratio=1.036, 2.080, 2.591, 1.615, 95% confidence interval as 1.020-1.052, 1.407-3.075, 1.791-3.748, 1.114-2.341, P<0.05). (4) Interaction analysis of MMR and adverse clinicopathological features on survival outcomes. Results of interaction analysis showed that the multiplication interaction effect between the number of lymph node harvest <12 and MMR protein status was significant on DFS of colon cancer patients ( hazard ratio=3.923, 95% confidence interval as 1.057-14.555, P<0.05). The additive interaction effects between age and MMR protein status, between high grade tumor and MMR protein status were significant on OS of colon cancer patients ( RERI=-0.033, -1.304, 95% confidence interval as -0.049 to -0.018, -2.462 to -0.146). Conclusions:There is an interaction between the MMR protein status and the adverse clinicopathological features (the number of lymph node harvest <12, high grade tumor) on prognosis of colon cancer patients of stage Ⅰ-Ⅲ. In patients of dMMR, the number of lymph node harvest <12 has a stronger predictive effect on poor prognosis. In patients of pMMR, the high grade tumor has a stronger predictive effect on poor prognosis.

Objective:To investigate the application value of transanal endoscopic intersphincteric resection (taE-ISR) in sphincter preservation for low rectal cancer.Methods:The pro-pensity score matching and retrospective cohort study was conducted. The clinicopathological data of 278 patients with low rectal cancer who were admitted to 5 medical centers, including Ruijin Hospital of Shanghai Jiaotong University School of Medicine et al, from January 2017 to December 2021 were collected. There were 178 males and 100 females, aged 58 (range, 49-64)years. Of 278 pati-ents, 147 cases undergoing taE-ISR were divided into the taE-ISR group, and 131 cases undergoing intersphincteric resection (ISR) were divided into the ISR group. Observation indicators:(1) propen-sity score matching and comparison of general data of patients between the two groups after matching; (2) comparison of intraoperative and postoperative conditions between the two groups; (3) long-term follow-up of the two groups; (4) analysis of risk factors affecting sphincter preservation for low rectal cancer. Propensity score matching was done by the 1∶1 nearest neighbor matching method, with a caliper value of 0.05. Propensity score matching analysis was done using the Matching package. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was conducted using the Student′s t test. Measurement data with skewed distribution were represented as M( Q1, Q3), and comparison between groups was conducted using the Wilcoxon rank sum test. Count data were described as absolute numbers or percentages, and comparison between groups was conducted using the Pearson chi-square test or Fisher exact probability. The Kaplan-Meier method was used to calculate survival rate and plot survival curve, and the Log-Rank test was used for survival analysis. Multivariate analysis was conducted using the Logistic regression model with the "glm2" package. The forest plot was used to show the risk factors affecting sphincter preservation for low rectal cancer. Results:(1) Propensity score matching and comparison of general data of patients between the two groups after matching. Of 278 patients, 180 cases were successfully matched, including 90 cases in the taE-ISR group and 90 cases in the ISR group, respectively. After propensity score matching, the elimination of distance between ischial tuberosities and distance from ischial tuberosity to the skin of buttocks confounding bias ensured comparability between the two groups. (2) Comparison of intraoperative and postoperative conditions between the two groups. Cases with positive distal margins, cases with specimen integrity, cases with sphincter preservation were 1, 88, 88 in the taE-ISR group and 8, 78, 74 in the ISR group, showing significant differences between the two groups ( P<0.05). (3) Long-term follow-up of the two groups. The median follow-up time was 4.3(range, 3.8-5.0)years of the taE-ISR group and 4.1(range, 3.4-4.7)years of the ISR group. The overall survival rate, disease-free survival rate and cumulative recurrence rate were 100.0%, 95.6% and 2.2% of the taE-ISR group, versus 98.9%, 87.8% and 10.0% of the ISR group, showing no significant difference in overall survival rate between the two groups ( χ2=0.97, P>0.05) and significant differences in disease-free survival rate and cumulative recurrence rate between the two groups ( χ2=4.05, 5.26, P<0.05). (4) Analysis of risk factors affecting sphincter preservation for low rectal cancer. Results of multivariate analysis showed that taE-ISR, distance from the tumor to the anus, and adjacent organ damage were independent factors affecting sphincter preservation for low rectal cancer ( odds ratio=0.86, 0.88, 1.35, 95% confidence interval as 0.79-0.93, 0.83-0.92, 1.04-1.74, P<0.05). In further analysis, there were significant differences in sphincter preservation and defecatory dysfunction between the 21 cases with neoadjuvant therapy in the taE-ISR group and the 19 cases with neoadjuvant therapy in the ISR group ( P<0.05). Conclusions:The taE-ISR is safe and feasible for patients with low rectal cancer. Compared with ISR, taE-ISR can significantly improve surgical quality, sphincter preservation rate and patient prognosis.

Traumatic supraorbital fissure syndrome (TSOFS) is a symptom complex caused by nerve entrapment in the supraorbital fissure after skull base trauma. If the compressed cranial nerve in the supraorbital fissure is not decompressed surgically, ptosis, diplopia and eye movement disorder may exist for a long time and seriously affect the patients′ quality of life. Since its overall incidence is not high, it is not familiarized with the majority of neurosurgeons and some TSOFS may be complicated with skull base vascular injury. If the supraorbital fissure surgery is performed without treatment of vascular injury, it may cause massive hemorrhage, and disability and even life-threatening in severe cases. At present, there is no consensus or guideline on the diagnosis and treatment of TSOFS that can be referred to both domestically and internationally. To improve the understanding of TSOFS among clinical physicians and establish standardized diagnosis and treatment plans, the Skull Base Trauma Group of the Neurorepair Professional Committee of the Chinese Medical Doctor Association, Neurotrauma Group of the Neurosurgery Branch of the Chinese Medical Association, Neurotrauma Group of the Traumatology Branch of the Chinese Medical Association, and Editorial Committee of Chinese Journal of Trauma organized relevant experts to formulate Chinese expert consensus on the diagnosis and treatment of traumatic supraorbital fissure syndrome ( version 2024) based on evidence of evidence-based medicine and clinical experience of diagnosis and treatment. This consensus puts forward 12 recommendations on the diagnosis, classification, treatment, efficacy evaluation and follow-up of TSOFS, aiming to provide references for neurosurgeons from hospitals of all levels to standardize the diagnosis and treatment of TSOFS.

BACKGROUND:Ankylosing spondylitis is a chronic inflammatory disease with chronic rheumatic immunity.Soft tissue ossification and fusion and spinal stiffness can cause biomechanical changes. OBJECTIVE:To reconstruct the lumbar-sacral intervertebral disc in ankylosing spondylitis patients with lumbar kyphosis by finite element analysis,and to study the range of motion of each segment of T11-S1 and the biomechanical characteristics of annulus fibrosus and nucleus pulposus. METHODS:The imaging data were obtained from an ankylosing spondylitis patient with lumbar kyphosis.The original CT image data of continuously scanned spine were imported into Mimics 21.0 in DICOM format,and T11-S1 was reconstructed respectively.The established model was imported into 3-Matic software in the format of"Stl"to reconstruct the intervertebral disc,and the fibrous intervertebral disc model was obtained.The improved model was further imported into Hypermesh software,and the vertebra,nucleus pulposus,annulus fibrosus and ligament were mesh-divided.After the material properties were given,the model was imported into ABAQUS software to observe the range of motion of each vertebral body in seven different working conditions of T11-S1,and analyze the biomechanical characteristics of each segment of annulus fibrosus and nucleus pulposus. RESULTS AND CONCLUSION:(1)The range of motion of L1 vertebrae was higher than that of other vertebrae under six different working conditions:extension,forward flexion,rotation(left and right),and lateral flexion(left and right).The maximum range of motion was 2.18° during L1 vertebral flexion,and the minimum range of motion was 0.12° during L5 vertebral extension.(2)The annular fiber flexion at L2-L3 segments was greater than the extension(P<0.05),and the annular fiber flexion at L3-L4 and L4-L5 segments was less than the extension(P<0.05).The left rotation of L1-L2 annular fibers was greater than the right rotation(P<0.05).The left flexion of the annulus was greater than the right flexion in L1-L2,L2-L3,L3-L4,L4-L5 and L5-S1 segments(P<0.05).(3)The nucleus pulposus stresses of T11-L12,L1-L2,L2-L3,L3-L4 and L4-L5 segments in forward flexion were greater than in extension(P<0.05).The left rotation of T12-L1 and L3-L4 segments was smaller than the right rotation(P<0.05),and that of T11-T12,L1-L2,and L2-L3 segments was larger than the right rotation(P<0.05).The left flexion was larger than the right flexion in the T11-S1 segment.(4)It is concluded that in ankylosing spondylitis patients with lumbar kyphosis,the minimum range of motion of the vertebral body is located at the L5 vertebral body in extension.To prevent fractures,it is recommended to avoid exercise in the extension position.During the onset of lumbar kyphosis in patients with ankylosing spondylitis,the maximum stress of the annulus fibrosus and nucleus pulposus is located in the L1-L2 segment,which is fixed and will not alter with the change of body position.The late surgical treatment and correction of deformity should focus on releasing the pressure of the annulus fibrosus and nucleus pulposus in this segment to avoid the rupture of the annulus fibrosus and the injury of the nucleus pulposus.

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.