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 synovial fluid from patients with rheumatoid arthritis(RA)on the polarization of normal neutrophils and the MEK/ERK signaling pathway,thereby providing experimental evidence to elucidate the pathological mechanisms of RA and offering novel insights into its treatment.Methods Synovial fluid samples were collected from 20 RA patients and 20 osteoarthritis(OA)patients.ELISA was used to measure the levels of interferon-gamma(IFN-γ),tumor necrosis factor-alpha(TNF-α),transforming growth factor-beta(TGF-β)and interleukin-8(IL-8)in the synovial fluid.Neutrophils were isolated from the peripheral blood of healthy donors,and their purity was confirmed by flow cytometry.Neutrophils were then treated with synovial fluid and divided into four groups:Control(untreated),RA(treated with 10％RA synovial fluid),OA(treated with 10％OA synovial fluid),and anti-IFN-β(treated with 20 μg anti-IFN-β antibody as an N2-type control).Western blot was used to assess the changes in the expression of IFN-γ,TNF-α,TGF-β,MEK,p-MEK,ERK and p-ERK.Additionally,the MEK inhibitor PD0325901 was used to block the MEK/ERK pathway,and subsequent changes in IFN-γ and TGF-β expression in neutrophils were evaluated.Results The levels of IFN-γ,TNF-α,TGF-β and IL-8 in the synovial fluid of RA patients were significantly higher than those in OA patients.After intervention with RA synovial fluid,the relative expression of IFN-γ and TNF-α in neutrophils were significantly increased compared to those in the untreated control group and the OA group.While,TGF-β expression in the RA group was lower than that in both the control and anti-IFN-β groups.The relative expression of p-MEK and p-ERK in the RA group were significantly higher than those in the control,OA and Anti-IFN-β groups.Upon addition of the MEK inhibitor,the relative expression of p-MEK and p-ERK were reduced.Furthermore,in both the RA and OA groups,the relative expression levels of IFN-γ decreased,while the expression of TGF-β increased.Conclusion Synovial fluid from RA patients contains higher of IFN-γ,TNF-αand TGF-β,which activate neutrophils through phosphorylation of the MEK/ERK signaling pathway,promoting their polarization toward the pro-inflammatory N1 phenotype.

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 explore the effects of exosomal CXCL on the biological behavior of cervical cancer cells and its underlying mechanisms.[Methods]Chemokine CXCL was first screened through bioinformatics databases.The GEPIA database was analyze CXCL expression in cervical cancer tissues and adjacent normal cervical tissues.Western blot was performed to detect CXCL expression levels in cervical cancer cells(Caski)and normal cervical epithelial cells(H8).The successful isolation of exosomes was confirmed by nanoparticle tracking analysis,transmission electron microscopy(TEM)and Western blot.ELISA was employed to detect the expression level of exosomes CXCL was determined by ELISA.After CXCL knockdown via siRNA transfection,cells were divided into three groups:blank control,negative control and experimental groups.Cell proliferation was evaluated using the CCK-8 assay,while cell migration and invasion were assessed by Transwell assays.[Results]Exosomal CXCL expression was significantly upregulated in cervical cancer cells compared with normal cervical epithelial cells(P<0.01),and also markedly elevated in cervical cancer tissues compared with adjacent normal tissues.After low expression of CXCL knockdown significantly reduced CXCL expression in both cancer cells and their derived exosomes(P<0.05).Low expression markedly inhibited the proliferation,invasion and migration abilities[Conclusion]Silencing exosomal CXCL may inhibit the malignant biological behavior of cancer cells.

Objective To investigate the effects of extracellular vesicles(EVs)derived from synovial fluid of rheumatoid arthritis(RA)patients on angiogenesis of human umbilical vein endothelial cells,and to preliminarily explore the underlying mechanisms.Methods Synovial fluid samples of knee joint were collected from 20 patients with RA and 20 patients with osteoarthritis(OA)in this study.EVs were purified using ultracentrifugation.The morphology and size of EVs were observed by transmission electron microscopy and nanoparticle tracking analysis.CD9,CD63,cytochrome c(Cyt-c),vascular endothelial growth factor(VEGF),lysyl oxidase(LOX),matrix metalloproteinase 2(MMP2),tumour necrosis factor alpha(TNF-α),transforming growth factor beta1(TGF-β1)in EVs were detected using Western blot.Human umbilical vein endothelial cells(HUVEC)were treated with the EVs.The growth,migration and angiogenesis of HUVEC were observed by CCK8 assay,TranswellTM chamber assay,scratch test and matrigel angiogenesis assay,respectively.The effect of EVs on the PI3K/AKT pathway in HUVEC was assessed using Western blot.Results Both EVs from RA synovial fluid(RA-EVs)and OA synovial fluid(OA-EVs)were cup-shaped,mainly between 30-400 nm in diameter,expressing CD63 and CD9,but not Cyt-c.RA-EVs carried more VEGF,LOX,MMP2,TNF-α and TGF-β1 than OA-EVs.Compared with the OA-EVs intervention,RA-EVs significantly promoted the proliferation,migration,and angiogenesis of HUVECs,as well as upregulated PI3K/AKT phosphorylation.The inhibitor of PI3K suppressed angiogenesis induced by EVs.Conclusion EVs in synovial fluid of RA carried more cytokines and enzymes that related angiogenesis and inflammation.These EVs exert their pro-angiogenic effects by activating the PI3K/AKT pathway,then contributing to the pathological progression of RA.

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.

Objective To characterize the changing species distribution and antibiotic resistance profiles of respiratory isolates in hospitals participating in the CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021.Methods Commercial automated antimicrobial susceptibility testing systems and disk diffusion method were used to test the susceptibility of respiratory bacterial isolates to antimicrobial agents following the standardized technical protocol established by the CHINET program.Results A total of 589 746 respiratory isolates were collected from 2015 to 2021.Overall,82.6％of the isolates were Gram-negative bacteria and 17.4％were Gram-positive bacteria.The bacterial isolates from outpatients and inpatients accounted for(6.0±0.9)％and(94.0±0.1)％,respectively.The top microorganisms were Klebsiella spp.,Acinetobacter spp.,Pseudomonas aeruginosa,Staphylococcus aureus,Haemophilus spp.,Stenotrophomonas maltophilia,Escherichia coli,and Streptococcus pneumoniae.Each microorganism was isolated from significantly more males than from females(P＜0.05).The overall prevalence of methicillin-resistant S.aureus(MRSA)was 39.9％.The prevalence of penicillin-resistant S.pneumoniae was 1.4％.The prevalence of extended-spectrum β-lactamase(ESBL)-producing E.coli and K.pneumoniae was 67.8％and 41.3％,respectively.The overall prevalence of carbapenem-resistant E.coli,K.pneumoniae,Enterobacter cloacae,Pseudomonas aeruginosa,and Acinetobacter baumannii was 3.7％,20.8％,9.4％,29.8％,and 73.3％,respectively.The prevalence of β-lactamase was 96.1％in Moraxella catarrhalis and 60.0％in Haemophilus influenzae.The H.influenzae isolates from children(＜18 years)showed significantly higher resistance rates to β-lactam antibiotics than the isolates from adults(P＜0.05).Conclusions Gram-negative bacteria are still predominant in respiratory isolates associated with serious antibiotic resistance.Antimicrobial resistance surveillance should be strengthened in clinical practice to support accurate etiological diagnosis and appropriate antimicrobial therapy based on antimicrobial susceptibility testing results.

AIM:To explore the role and mechanism of calcium-sensing receptor(CaSR)in regulating macro-phage polarization in hypertensive rats.METHODS:Male spontaneously hypertensive rats(SHR)and Wistar-Kyoto(WKY)rats were categorized into WKY group,SHR group,SHR+R568(CaSR agonist)group,and SHR+NPS2143(CaSR inhibitor)group.The thoracic aorta was isolated,and the expression of CaSR and macrophage polarization markers in the aorta was observed through immunofluorescence staining.The primary peritoneal macrophages of SHR and WKY rats were aseptically extracted following anesthesia.After intervention with R568 and NPS2143,the expression levels of M1 and M2 markers of peritoneal macrophages were observed by Western blot and immunofluorescence staining.The levels of interleukin(IL)-1β and IL-10 were measured by ELISA.The concentration of Ca2+in peritoneal macrophages was mea-sured by immunofluorescence.Western blot was employed to identify the expression of CaSR and nucleotide-binding oligo-merization domain-like receptor protein 3(NLRP3)inflammasome components.Following anesthesia,vascular smooth muscle cells(VSMCs)were isolated from SHR using an adherent method.Subsequently,a co-culture system was estab-lished with macrophage supernatant.The optimal action time for this co-culture system was determined through CCK-8 as-say.RESULTS:Compared with SHR group,activation of CaSR resulted in a significant decrease in the protein expres-sion of M1 polarization markers(P<0.05)and a concomitant increase in the protein expression of M2 polarization markers in the aorta(P<0.05).Compared with SHR group,administration of R568 led to a significant decrease in the protein ex-pression of M1 polarization markers(P<0.05)and a concomitant increase in the protein expression of M2 polarization markers(P<0.05)in peritoneal macrophages.Additionally,there was a notable reduction in the protein levels of NLRP3 inflammasome components(P<0.05).Furthermore,the fluorescence intensity of intracellular Ca2+was significantly en-hanced following R568 treatment(P<0.05).After administration of MCC950,an NLRP3 inflammasome inhibitor,the re-sults were consistent with those observed following R568 treatment,demonstrating statistical significance(P<0.05).This effect was reversed by the combined intervention of U73122,a phospholipase C(PLC)inhibitor(P<0.05).Compared with the control(0 h),the 24-h peritoneal macrophage supernatant exhibited the strongest capacity to enhance the viabili-ty of VSMCs after 24 h of culture(P<0.05).CONCLUSION:In hypertensive rats,the CaSR inhibits NLRP3 inflamma-some activation via the PLC-Ca2+signaling pathway,thereby mediating an increase in macrophage polarization towards the M2 phenotype and a decrease towards the M1 phenotype.