Objective To investigate the distribution and antimicrobial resistance profiles of common pathogens isolated from cerebrospinal fluid(CSF)in CHINET program from 2015 to 2021.Methods The bacterial strains isolated from CSF were identified in accordance with clinical microbiology practice standards.Antimicrobial susceptibility test was conducted using Kirby-Bauer method and automated systems per the unified CHINET protocol.Results A total of 14 014 bacterial strains were isolated from CSF samples from 2015 to 2021,including the strains isolated from inpatients(95.3％)and from outpatient and emergency care patients(4.7％).Overall,19.6％of the isolates were from children and 80.4％were from adults.Gram-positive and Gram-negative bacteria accounted for 68.0％and 32.0％,respectively.Coagulase negative Staphylococcus accounted for 73.0％of the total Gram-positive bacterial isolates.The prevalence of MRSA was 38.2％in children and 45.6％in adults.The prevalence of MRCNS was 67.6％in adults and 69.5％in children.A small number of vancomycin-resistant Enterococcus faecium(2.2％)and linezolid-resistant Enterococcus faecalis(3.1％)were isolated from adult patients.The resistance rates of Escherichia coli and Klebsiella pneumoniae to ceftriaxone were 52.2％and 76.4％in children,70.5％and 63.5％in adults.The prevalence of carbapenem-resistant E.coli and K.pneumoniae(CRKP)was 1.3％and 47.7％in children,6.4％and 47.9％in adults.The prevalence of carbapenem-resistant Acinetobacter baumannii(CRAB)and Pseudomonas aeruginosa(CRPA)was 74.0％and 37.1％in children,81.7％and 39.9％in adults.Conclusions The data derived from antimicrobial resistance surveillance are crucial for clinicians to make evidence-based decisions regarding antibiotic therapy.Attention should be paid to the Gram-negative bacteria,especially CRKP and CRAB in central nervous system(CNS)infections.Ongoing antimicrobial resistance surveillance is helpful for optimizing antibiotic use in CNS infections.

Objective To investigate the antimicrobial resistance of clinical isolates from elderly patients(≥65 years)in major medical institutions across China.Methods Bacterial strains were isolated from elderly patients in 52 hospitals participating in the CHINET Antimicrobial Resistance Surveillance Program during the period from 2015 to 2021.Antimicrobial susceptibility test was carried out by disk diffusion method and automated systems according to the same CHINET protocol.The data were interpreted in accordance with the breakpoints recommended by the Clinical and Laboratory Standards Institute(CLSI)in 2021.Results A total of 514 715 nonduplicate clinical isolates were collected from elderly patients in 52 hospitals from January 1,2015 to December 31,2021.The number of isolates accounted for 34.3％of the total number of clinical isolates from all patients.Overall,21.8％of the 514 715 strains were gram-positive bacteria,and 78.2％were gram-negative bacteria.Majority(90.9％)of the strains were isolated from inpatients.About 42.9％of the strains were isolated from respiratory specimens,and 22.9％were isolated from urine.More than half(60.7％)of the strains were isolated from male patients,and 39.3％isolated from females.About 51.1％of the strains were isolated from patients aged 65-＜75 years.The prevalence of methicillin-resistant strains(MRSA)was 38.8％in 32 190 strains of Staphylococcus aureus.No vancomycin-or linezolid-resistant strains were found.The resistance rate of E.faecalis to most antibiotics was significantly lower than that of Enterococcus faecium,but a few vancomycin-resistant strains(0.2％,1.5％)and linezolid-resistant strains(3.4％,0.3％)were found in E.faecalis and E.faecium.The prevalence of penicillin-susceptible S.pneumoniae(PSSP),penicillin-intermediate S.pneumoniae(PISP),and penicillin-resistant S.pneumoniae(PRSP)was 94.3％,4.0％,and 1.7％in nonmeningitis S.pneumoniae isolates.The resistance rates of Klebsiella spp.(Klebsiella pneumoniae 93.2％)to imipenem and meropenem were 20.9％and 22.3％,respectively.Other Enterobacterales species were highly sensitive to carbapenem antibiotics.Only 1.7％-7.8％of other Enterobacterales strains were resistant to carbapenems.The resistance rates of Acinetobacter spp.(Acinetobacter baumannii 90.6％)to imipenem and meropenem were 68.4％and 70.6％respectively,while 28.5％and 24.3％of P.aeruginosa strains were resistant to imipenem and meropenem,respectively.Conclusions The number of clinical isolates from elderly patients is increasing year by year,especially in the 65-＜75 age group.Respiratory tract isolates were more prevalent in male elderly patients,and urinary tract isolates were more prevalent in female elderly patients.Klebsiella isolates were increasingly resistant to multiple antimicrobial agents,especially carbapenems.Antimicrobial resistance surveillance is helpful for accurate empirical antimicrobial therapy in elderly patients.

Objective To investigate the effect of postoperative reduction quality in femoral neck fracture internal fixation on mechanical properties of the femoral head from the perspective of trabecular bone biomechanics.Methods From patients who underwent hip replacement surgery for femoral neck fractures,a total of 26 femoral head slice specimens were obtained.The central axis of the primary compressive trabeculae was defined as the 0° group,with the intersection point of the primary compressive trabeculae and the femoral calcar serving as the center.By rotating the specimens to simulate different reduction angles,the cut femoral head slice specimens were randomly divided into five groups:-10°,-5°,0°,5°,and 10°,representing femoral heads with varying reduction qualities.The specimens were subjected to single compression load tests and fatigue load tests.The load was set from 70 N to 1 400 N,at a frequency of 1 Hz,with 10 000 cycles.Axial stiffness,displacement,and the number of collapse cycles were measured,to compare the biomechanical properties of femoral head specimens under different reduction qualities.Results There were differences in the axial stiffness,displacement,and number of collapse cycles among the femoral head specimens in different groups.Under 800 N load,the axial stiffness of 0° group was significantly greater than that of±10° groups(P＜0.05).The axial stiffness of 0° group was also greater than that of the±5° groups,but the differences were not statistically significant(P＞0.05).The axial stiffness of±5° groups was greater than that of±10° groups(P＜0.05).0° group had a lower displacement than±5° groups and±10° groups.However,the differences in displacement between 0° group and±5° groups were not statistically significant(P＞0.05),while the differences between the 0° group and±10° groups were statistically significant(P＜0.05).The differences in displacement between±5° groups and±10° groups were also statistically significant(P＜0.05).0° group had a significantly higher number of collapse cycles than±10° groups(P＜0.05).The number of collapse cycles in 0° group was also higher than that in±5° groups,but the differences were not statistically significant(P＞0.05).The number of collapse cycles in±5° groups was significantly higher than that±10° groups(P＜0.05).Conclusions The quality of reduction after internal fixation of femoral neck fractures significantly affects the biomechanical properties of the femoral head.This study provides a scientific basis for optimizing treatment and postoperative management,aiming to improve clinical outcomes and patients' quality of life.

Objective To explore the role of cysteine aspartic protease-8(Caspase-8)/gasdermin E(GSDME)pathway in the regulation of macrophage pyroptosis in myocardial infarction(MI)rat model and its possible mechanism.Methods Thirty rats were randomly divided into sham operation group,MI group and Caspase-8 inhibition(Z-IETD-FMK)group,with 10 rats in each group.The cultured rat macrophages RMa-bm were divided into control group,hypoxia group and Z-IETD-FMK group.The pathological changes of myocardial tissue were detected by H&E staining.Masson staining was used to detect myocardial fibrosis.The protein and mRNA levels of Caspase-8 and GSDME in myocardial tissue and Caspase-8,GSDME,NLR family Pyrin domain protein 3(NLRP3),apoptosis-related speck-like protein(ASC)and Caspase-1 in macrophages were detected by RT-qPCR and Western blotting.The levels of IL-1β and IL-18 in macrophages were detected by ELISA.TUNEL staining was used to detect apoptosis of cardiomyocytes and macrophages.Results Compared with the sham operation group,myocardial tissue of rats in MI group was broken and disturbed,inflammatory cell infiltration,a large amount of collagen fiber deposition in the gap,cell apoptosis increased and the expression of Caspase-8,GSDME protein and mRNA in myocardial tissue increased,the differences were statistically significant(t=16.19,27.60;21.18,23.73,all P<0.05).Compared with MI group,Z-IETD-FMK group improved myocardial structural damage,reduced inflammatory cells and collagen deposition,cell apoptosis decreased and decreased Caspase-8,GSDME protein and mRNA expressions in myocardial tissue,with statistical significance(t=20.34,14.56;11.97,24.46,all P<0.05).Compared with the control group,the apoptosis of macrophages in hypoxia group was increased,and the protein and mRNA expressions of Caspase-8,GSDME,NLRP3,ASC,Caspase-1 in macrophages were increased(tprotein=17.53～120.90,tmRNA=18.42～60.30),the contents of IL-1β and IL-18 in macrophages were increased(t=25.88,45.74),and the differences were staistically significant(all P<0.05).Compared with the hypoxia group,the apoptosis of macrophages in Z-IETD-FMK group was decreased,and the protein and mRNA expressions of Caspase-8,GSDME,NLRP3,ASC,Caspase-1 in macrophages were decreased(tprotein=17.08～35.08,tmRNA=11.21～47.96),IL-1β and IL-18 content decreased(t=27.38,25.82),and the differences were staistically significant(all P<0.05),respectively.Conclusion Down-regulating Caspase-8/GSDME pathway can improve myocardial injury and hypoxic macrophage scorch death in MI rats.

Objective To examine the changing prevalence and antimicrobial resistance profiles of Burkholderia cepacia in 52 hospitals across China from 2015 to 2021.Methods A total of 9 261 strains of B.cepacia were collected from 52 hospitals between January 1,2015 and December 31,2021.Antimicrobial susceptibility of the strains was tested using Kirby-Bauer method or automated antimicrobial susceptibility testing systems according to a unified protocol.The results were interpreted according to the breakpoints released in the Clinical & Laboratory Standards Institute(CLSI)guidelines(2023 edition).Results A total of 9 261 strains of B.cepacia were isolated from all age groups,especially elderly patients.The proportion was 11.1％(1 032 strains)in children,significantly lower than the proportion in adults.About half(46.5％,4 310/9 261)of the strains were isolated from patients at least 60 years old and 42.3％(3 919/9 261)of the strains were isolated from young adults.Most isolates(71.1％)were isolated from sputum and respiratory secretions,followed by urine(10.7％)and blood samples(8.1％).B.cepacia isolates were highly susceptible to the five antimicrobial agents recommended in the CLSI M100 document(33rd edition,2023).B.cepacia isolates showed relatively higher resistance rates to meropenem and levofloxacin.However,the resistance rates to ceftazidime,trimethoprim-sulfamethoxazole,and minocycline remained below 8.1％.The percentage of B.cepacia strains resistant to levofloxacin was the highest compared to other antibiotics in any of the three age groups(from 12.4％in the patients＜18 years old to 20.6％in the patients aged 60 years or older).Conclusions B.cepacia is one of the clinically important non-fermenting gram-negative bacteria.Accurate and timely reporting of antimicrobial susceptibility test results and ongoing antimicrobial resistance surveillance are helpful for rational prescription of antimicrobial agents and proper prevention and control of nosocomial infections.

Objective To investigate the effects of miR-126 on myocardial remodeling and macrophage polarization after acute myocardial infarction(AMI).Methods(1)Twenty-one rats were divided into a sham operation group and an AMI group.The AMI group was further divided into postoperative days 1,3,5,7,9,and 11 days(AMI-1,AMI-3,AMI-5,AMI-7,AMI-9,AMI-11),with 3 rats in each group,and postoperative day 3 was selected for subsequent study.(2)Thirty rats were randomly divided into three groups:sham operation group,AMI group and miR-126 overexpression group,with 10 rats in each group.RT-qPCR was used to detect the expression levels of miR-126 mRNA.2,3,5-Triphenyltetrazole chloride(TTC)staining was used to detect the infarct size.Myocardial fibrosis was detected by Masson staining.The cross-sectional area of the myocardium was determined by H&E staining.Immunofluorescence staining was used to detect the protein levels of CD86 and CD206 in myocardial tissue.Western blotting was used to detect the protein levels of CD86 and CD206 in myocardial tissue.The levels of tumor necrosis factor-α(TNF-α),interleukin-1β(IL-1β)and IL-6 in serum were detected by ELISA kit.Results Compared with the sham operation group,the expression level of miR-126 mRNA in myocardial tissue of rats in the AMI group was significantly decreased on postoperative day 1(P<0.05),reached the lowest level on postoperative day 3.And then although it rose to a certain extent,it remained lower than that of the sham operation group on postoperative day 11(P<0.05),and postoperative day 3 was selected for further study.Compared with the sham operation group,the expression of miR-126 mRNA in myocardial tissue of the AMI group was decreased(P<0.05),and the myocardial fibrosis,infarct size and myocardial cross-sectional area were increased(P<0.05).The expression of CD86 protein in myocardial tissue was increased and the expression of CD206 protein was decreased(P<0.05).The serum levels of TNF-α,IL-6 and IL-1β were increased(P<0.05).Compared with the AMI group,the rats in the miR-126 overexpression group had a significant increase in the mRNA expression of miR-126 in myocardial tissue(P<0.05),a significant reduction in myocardial fibrosis,infarct size,and myocardial cross-sectional area(P<0.05),a significant reduction in the expression of CD86 protein in myocardial tissue,and a significant increase in the expression of CD206 protein(P<0.05).The serum levels of TNF-α,IL-6 and IL-1β were significantly decreased(P<0.05).Conclusion Over-expression of miR-126 can improve myocardial remodeling and promote M2 macrophage polarization in AMI rats.

Objective To investigate the effect of postoperative reduction quality in femoral neck fracture internal fixation on mechanical properties of the femoral head from the perspective of trabecular bone biomechanics.Methods From patients who underwent hip replacement surgery for femoral neck fractures,a total of 26 femoral head slice specimens were obtained.The central axis of the primary compressive trabeculae was defined as the 0° group,with the intersection point of the primary compressive trabeculae and the femoral calcar serving as the center.By rotating the specimens to simulate different reduction angles,the cut femoral head slice specimens were randomly divided into five groups:-10°,-5°,0°,5°,and 10°,representing femoral heads with varying reduction qualities.The specimens were subjected to single compression load tests and fatigue load tests.The load was set from 70 N to 1 400 N,at a frequency of 1 Hz,with 10 000 cycles.Axial stiffness,displacement,and the number of collapse cycles were measured,to compare the biomechanical properties of femoral head specimens under different reduction qualities.Results There were differences in the axial stiffness,displacement,and number of collapse cycles among the femoral head specimens in different groups.Under 800 N load,the axial stiffness of 0° group was significantly greater than that of±10° groups(P＜0.05).The axial stiffness of 0° group was also greater than that of the±5° groups,but the differences were not statistically significant(P＞0.05).The axial stiffness of±5° groups was greater than that of±10° groups(P＜0.05).0° group had a lower displacement than±5° groups and±10° groups.However,the differences in displacement between 0° group and±5° groups were not statistically significant(P＞0.05),while the differences between the 0° group and±10° groups were statistically significant(P＜0.05).The differences in displacement between±5° groups and±10° groups were also statistically significant(P＜0.05).0° group had a significantly higher number of collapse cycles than±10° groups(P＜0.05).The number of collapse cycles in 0° group was also higher than that in±5° groups,but the differences were not statistically significant(P＞0.05).The number of collapse cycles in±5° groups was significantly higher than that±10° groups(P＜0.05).Conclusions The quality of reduction after internal fixation of femoral neck fractures significantly affects the biomechanical properties of the femoral head.This study provides a scientific basis for optimizing treatment and postoperative management,aiming to improve clinical outcomes and patients' quality of life.

Objective To explore the role of cysteine aspartic protease-8(Caspase-8)/gasdermin E(GSDME)pathway in the regulation of macrophage pyroptosis in myocardial infarction(MI)rat model and its possible mechanism.Methods Thirty rats were randomly divided into sham operation group,MI group and Caspase-8 inhibition(Z-IETD-FMK)group,with 10 rats in each group.The cultured rat macrophages RMa-bm were divided into control group,hypoxia group and Z-IETD-FMK group.The pathological changes of myocardial tissue were detected by H&E staining.Masson staining was used to detect myocardial fibrosis.The protein and mRNA levels of Caspase-8 and GSDME in myocardial tissue and Caspase-8,GSDME,NLR family Pyrin domain protein 3(NLRP3),apoptosis-related speck-like protein(ASC)and Caspase-1 in macrophages were detected by RT-qPCR and Western blotting.The levels of IL-1β and IL-18 in macrophages were detected by ELISA.TUNEL staining was used to detect apoptosis of cardiomyocytes and macrophages.Results Compared with the sham operation group,myocardial tissue of rats in MI group was broken and disturbed,inflammatory cell infiltration,a large amount of collagen fiber deposition in the gap,cell apoptosis increased and the expression of Caspase-8,GSDME protein and mRNA in myocardial tissue increased,the differences were statistically significant(t=16.19,27.60;21.18,23.73,all P<0.05).Compared with MI group,Z-IETD-FMK group improved myocardial structural damage,reduced inflammatory cells and collagen deposition,cell apoptosis decreased and decreased Caspase-8,GSDME protein and mRNA expressions in myocardial tissue,with statistical significance(t=20.34,14.56;11.97,24.46,all P<0.05).Compared with the control group,the apoptosis of macrophages in hypoxia group was increased,and the protein and mRNA expressions of Caspase-8,GSDME,NLRP3,ASC,Caspase-1 in macrophages were increased(tprotein=17.53～120.90,tmRNA=18.42～60.30),the contents of IL-1β and IL-18 in macrophages were increased(t=25.88,45.74),and the differences were staistically significant(all P<0.05).Compared with the hypoxia group,the apoptosis of macrophages in Z-IETD-FMK group was decreased,and the protein and mRNA expressions of Caspase-8,GSDME,NLRP3,ASC,Caspase-1 in macrophages were decreased(tprotein=17.08～35.08,tmRNA=11.21～47.96),IL-1β and IL-18 content decreased(t=27.38,25.82),and the differences were staistically significant(all P<0.05),respectively.Conclusion Down-regulating Caspase-8/GSDME pathway can improve myocardial injury and hypoxic macrophage scorch death in MI rats.

Objective To examine the changing prevalence and antimicrobial resistance profiles of Burkholderia cepacia in 52 hospitals across China from 2015 to 2021.Methods A total of 9 261 strains of B.cepacia were collected from 52 hospitals between January 1,2015 and December 31,2021.Antimicrobial susceptibility of the strains was tested using Kirby-Bauer method or automated antimicrobial susceptibility testing systems according to a unified protocol.The results were interpreted according to the breakpoints released in the Clinical & Laboratory Standards Institute(CLSI)guidelines(2023 edition).Results A total of 9 261 strains of B.cepacia were isolated from all age groups,especially elderly patients.The proportion was 11.1％(1 032 strains)in children,significantly lower than the proportion in adults.About half(46.5％,4 310/9 261)of the strains were isolated from patients at least 60 years old and 42.3％(3 919/9 261)of the strains were isolated from young adults.Most isolates(71.1％)were isolated from sputum and respiratory secretions,followed by urine(10.7％)and blood samples(8.1％).B.cepacia isolates were highly susceptible to the five antimicrobial agents recommended in the CLSI M100 document(33rd edition,2023).B.cepacia isolates showed relatively higher resistance rates to meropenem and levofloxacin.However,the resistance rates to ceftazidime,trimethoprim-sulfamethoxazole,and minocycline remained below 8.1％.The percentage of B.cepacia strains resistant to levofloxacin was the highest compared to other antibiotics in any of the three age groups(from 12.4％in the patients＜18 years old to 20.6％in the patients aged 60 years or older).Conclusions B.cepacia is one of the clinically important non-fermenting gram-negative bacteria.Accurate and timely reporting of antimicrobial susceptibility test results and ongoing antimicrobial resistance surveillance are helpful for rational prescription of antimicrobial agents and proper prevention and control of nosocomial infections.

Objective To summarize the changing prevalence of carbapenem resistance in Enterobacterales based on the data of CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021 for improving antimicrobial treatment in clinical practice.Methods Antimicrobial susceptibility testing was performed using a commercial automated susceptibility testing system according to the unified CHINET protocol.The results were interpreted according to the breakpoints of the Clinical & Laboratory Standards Institute(CLSI)M100 31st ed in 2021.Results Over the seven-year period(2015-2021),the overall prevalence of carbapenem-resistant Enterobacterales(CRE)was 9.43％(62 342/661 235).The prevalence of CRE strains in Klebsiella pneumoniae,Citrobacter freundii,and Enterobacter cloacae was 22.38％,9.73％,and 8.47％,respectively.The prevalence of CRE strains in Escherichia coli was 1.99％.A few CRE strains were also identified in Salmonella and Shigella.The CRE strains were mainly isolated from respiratory specimens(44.23±2.80)％,followed by blood(20.88±3.40)％and urine(18.40±3.45)％.Intensive care units(ICUs)were the major source of the CRE strains(27.43±5.20)％.CRE strains were resistant to all the β-lactam antibiotics tested and most non-β-lactam antimicrobial agents.The CRE strains were relatively susceptible to tigecycline and polymyxins with low resistance rates.Conclusions The prevalence of CRE strains was increasing from 2015 to 2021.CRE strains were highly resistant to most of the antibacterial drugs used in clinical practice.Clinicians should prescribe antimicrobial agents rationally.Hospitals should strengthen antibiotic stewardship in key clinical settings such as ICUs,and take effective infection control measures to curb CRE outbreak and epidemic in hospitals.