By using thioflavin T(ThT)as displacement-based fluorescent probes,three kinds of aptasensors were constructed for rapid detection of three kinds of small molecules such as ochratoxin A(OTA),aflatoxin B1(AFB1)and adenosine.In the absence of target molecule,ThT bound with the aptamer to form an aptamer-ThT complex and exhibited a significant fluorescence response.Upon the addition of target molecule,because of the higher affinity between target and aptamer than that between ThT and the aptamer,ThT was displaced by the target molecule from the aptamer-ThT complex,resulting in weakened fluorescence signal.Based on this principle,the target molecule could be detected quantitatively.Further study through circular dichroism spectra showed that there was no significant change in the conformation of the aptamer after addition of ThT or target molecules.The stoichiometric ratios of ThT to OTAapt,AFB1apt and Adeapt measured through the method of equimolar continuous variation was 1∶1,1∶1 and 2∶1,respectively,and their dissociation constants were all larger than those between the target molecule and its aptamer.Therefore,the principle of this detection method was the displacement of fluorescent probe(ThT)in aptamer-ThT complex by target molecule,resulting in decrease of fluorescence intensity.Under optimal experimental conditions,the limits of detection(LODs)were 0.8 nmol/L for OTA,1.3 nmol/L for AFB1,and 0.10 μmol/L for adenosine,respectively.This method was label-free,simple to operate,with low cost,good selectivity and high sensitivity.The developed assay kit based on this method could be used for actual sample detection.

An adsorption and concentration sampling device for volatile organic compounds(VOCs)was designed in this work,which improved the long-term monitoring stability of the online monitoring system for VOC adsorption and concentration,and solved the issue of rapid attenuation of responses toward higher carbon compounds.The designed VOC desorption device achieved an average heating rate of 40 ℃/s,with a relative standard deviation(RSD)of 0.4％.Quantitative analysis of mixture of 116 kinds of different VOC standard gases was performed,and the test results showed that the qualification rate of standard curves increased significantly from 90％to 99％,the proportion of detection limits below 0.1 nmol/mol improved from 85％to 90％,and the proportion of residual levels in the system below 0.1 nmol/mol also increased from 85％to 90％.The stable monitoring period was extended from 20 d to over 30 d,making it more conducive to long-term unattended monitoring by the developed instrument.

Objective To understand the change in distribution and antimicrobial resistance of bacteria isolated from blood specimens of Hunan Province,and provide for the initial diagnosis and treatment of clinical bloodstream infection(BSI).Methods Data reported from member units of Hunan Province Antimicrobial Resistance Survei-llance System from 2012 to 2021 were collected.Bacterial antimicrobial resistance surveillance method was imple-mented according to the technical scheme of China Antimicrobial Resistance Surveillance System(CARSS).Bacteria from blood specimens and bacterial antimicrobial susceptibility testing results were analyzed by WHONET 5.6 soft-ware and SPSS 27.0 software.Results A total of 207 054 bacterial strains were isolated from blood specimens from member units in Hunan Province Antimicrobial Resistance Surveillance System from 2012 to 2021,including 107 135(51.7％)Gram-positive bacteria and 99 919(48.3％)Gram-negative bacteria.There was no change in the top 6 pathogenic bacteria from 2012 to 2021,with Escherichia coli(n=51 537,24.9％)ranking first,followed by Staphylococcus epidermidis(n=29 115,14.1％),Staphylococcus aureus(n=17 402,8.4％),Klebsiella pneu-moniae(17 325,8.4％),Pseudomonas aeruginosa(n=4 010,1.9％)and Acinetobacter baumannii(n=3 598,1.7％).The detection rate of methicillin-resistant Staphylococcus aureus(MRSA)decreased from 30.3％in 2015 to 20.7％in 2021,while the detection rate of methicillin-resistant coagulase-negative Staphylococcus(MRCNS)showed an upward trend year by year(57.9％-66.8％).No Staphylococcus was found to be resistant to vancomy-cin,linezolid,and teicoplanin.Among Gram-negative bacteria,constituent ratios of Escherichia coli and Klebsiella pneumoniae were 43.9％-53.9％and 14.2％-19.5％,respectively,both showing an upward trend(both P＜0.001).Constituent ratios of Pseudomonas aeruginosa and Acinetobacter baumannii were 3.6％-5.1％and 3.0％-4.5％,respectively,both showing a downward trend year by year(both P＜0.001).From 2012 to 2021,resistance rates of Escherichia coli to imipenem and ertapenem were 1.0％-2.0％and 0.6％-1.1％,respectively;presenting a downward trend(P＜0.001).The resistant rates of Klebsiella pneumoniae to meropenem and ertapenem were 7.4％-13.7％and 4.8％-6.4％,respectively,presenting a downward trend(both P＜0.001).The resistance rates of Pseudomonas aeruginosa and Acinetobacter baumannii to carbapenem antibiotics were 7.1％-15.6％and 34.7％-45.7％,respectively.The trend of resistance to carbapenem antibiotics was relatively stable,but has de-creased compared with 2012-2016.The resistance rates of Escherichia coli to the third-generation cephalosporins from 2012 to 2021 were 41.0％-65.4％,showing a downward trend year by year.Conclusion The constituent ra-tio of Gram-negative bacillus from blood specimens in Hunan Province has been increasing year by year,while the detection rate of carbapenem-resistant Gram-negative bacillus remained relatively stable in the past 5 years,and the detection rate of coagulase-negative Staphylococcus has shown a downward trend.

Objective To investigate changes in the distribution and antimicrobial resistance of bacteria isolated from cerebrospinal fluid(CSF)specimens in Hunan Province,and provide reference for correct clinical diagnosis and rational antimicrobial use.Methods Data reported by member units of Hunan Province Antimicrobial Resistance Surveillance System from 2012 to 2021 were collected according to China Antimicrobial Resistance Surveillance Sys-tem(CARSS)technical scheme.Data of bacteria isolated from CSF specimens and antimicrobial susceptibility tes-ting results were analyzed with WHONET 5.6 and SPSS 20.0 software.Results A total of 11 837 bacterial strains were isolated from CSF specimens from member units of Hunan Province Antimicrobial Resistance Surveillance Sys-tem from 2012 to 2021.The top 5 strains were coagulase-negative Staphylococcus(n=6 397,54.0％),Acineto-bacter baumannii(n=764,6.5％),Staphylococcus aureus(n=606,5.1％),Enterococcus faecium(n=465,3.9％),and Escherichia coli(n=447,3.8％).The detection rates of methicillin-resistant coagulase-negative Staphyloco-ccus(MRCNS)and methicillin-resistant Staphylococcus aureus(MRSA)were 58.9％-66.3％and 34.4％-62.1％,respectively.No Staphylococcus spp.were found to be resistant to vancomycin,linezolid,and teicoplanin.The de-tection rate of Enterococcus faecium was higher than that of Enterococcus faecalis,and the resistance rates of En-terococcus f aecium to penicillin,ampicillin,high concentration streptomycin and levofloxacin were all higher than those of Enterococcus faecalis(all P=0.001).Resistance rate of Streptococcus pneumoniae to penicillin was 85.0％,at a high level.Resistance rate of Escherichia coli to ceftriaxone was＞60％,while resistance rates to enzyme inhibitors and carbapenem antibiotics were low.Resistance rate of Klebsiella pneumoniae to ceftriaxone was＞60％,to en-zyme inhibitors piperacillin/tazobactam and cefoperazone/sulbactam was＞30％,to carbapenem imipenem and me-ropenem was about 30％.Resistance rates of Acinetobacter baumannii to most tested antimicrobial agents were＞60％,to imipenem and meropenem were 59.0％-79.4％,to polymyxin B was low.Conclusion Among the bac-teria isolated from CSF specimens,coagulase-negative Staphylococcus accounts for the largest proportion,and the overall resistance of pathogenic bacteria is relatively serious.Bacterial antimicrobial resistance surveillance is very important for the effective treatment of central nerve system infection.

Objective To investigate the distribution and antimicrobial susceptibility of clinically isolated bacteria from intensive care units(ICUs)in hospitals of Hunan Province Antimicrobial Resistance Surveillance System from 2012 to 2021.Methods According to China Antimicrobial Resistance Surveillance System,data of clinically isolated bacterial strains and antimicrobial susceptibility testing results of bacteria from ICUs reported by all member units of Hunan Province Antimicrobial Resistance Surveillance System were analyzed with WHONET 2022 software.Results From 2012 to 2021,the total number of bacteria isolated from ICUs of member units of the Hunan Province Antimi-crobial Resistance Surveillance System was 5 777-22 369,with Gram-negative bacteria accounting for 76.1％-78.0％annually.Staphylococcus aureus ranked first among isolated Gram-positive bacteria each year.The top 5 bacteria among Gram-negative bacteria were Acinetobacter baumannii,Klebsiella pneumoniae,Escherichia coli,Pseudo-monas aeruginosa,and Stenotrophomonas maltophilia.Detection rate of methicillin-resistant Staphylococcus aureus showed a downward trend year by year.No Staphylococcus spp.were found to be resistant to vancomycin,teico-planin and linezolid.Detection rates of vancomycin-resistant Enterococcus faecalis and vancomycin-resistant Entero-coccus faecium were 0.6-1.1％and 0.6％-2.2％,respectively.Resistance rates of Escherichia coli and Kleb-siella pneumoniae to imipenem were 3.1％-5.7％and 7.7％-20.9％,respectively.Resistance rates of Pseudo-monasaeruginosa and Acinetobacter baumannii to imipenem were 24.6％-40.1％and 76.1％-80.9％,respective-ly.Detection rates of carbapenem-resistant Pseudomonas aeruginosa declined year by year.Acinetobacter baumannii maintained high susceptibility to polymyxin B,with resistance rate＜10％.Conclusion Antimicrobial resistance of bacteria from ICUs is serious.Carbapenem-resistant Enterobacteriales has an upward trend after 2019.It is nece-ssary to strengthen the surveillance of bacterial resistance and carry out multidisciplinary collaboration.

Objective To understand the antimicrobial resistance of clinically isolated Enterococcus spp.in Hunan Province.Methods Surveillance data of Enterococcus spp.resistance from member units of Hunan Provincial Anti-microbial Resistance Surveillance System from 2012 to 2021 were collected.Data were cleaned according to a unified method,and WHONET 5.6 software was adopted for statistical analysis.Results From 2012 to 2021,a total of 110 652 non-repetitive Enterococcus spp.strains were included in the analysis,mainly Enterococcus faecalis and Enterococcus faecium,accounting for 46.9％(n=37 774)and 45.9％(n=36 968),respectively,followed by En-terococcus avium(2.5％,n=1 982),Enterococcus gallinarum(1.8％,n=1 428),and Enterococcus casseliflavus(1.5％,n=1 185).The main specimen sources of Enterococcus spp.was urine(51.8％,n=57 350),followed by secretions(9.6％,n=10 660)and bile(8.5％,n=9 377).From 2012 to 2021,the resistance rates of Enteroco-ccus faecalis to ampicillin,teicoplanin,and vancomycin were 5.5％-12.0％,1.3％-2.0％,and 0.6％-1.4％,respectively.The resistance rates of Enterococcus faecium to ampicillin,teicoplanin,and vancomycin were 69.2％-85.0％,1.5％-2.8％,and 0.7％-2.5％,respectively.Except for linezolid and minocycline,the resistance rates of Enterococcus faecium to tested antimicrobial agents were all higher than those of Enterococcus faecalis.The re-sistance rates of Enterococcus faecalis and Enterococcus faecium to vancomycin decreased from 1.4％and 2.1％in 2012 to 0.6％and 0.7％in 2021,respectively,presenting a decreased trend.Conclusion Clinically isolated En-terococcus spp.maintain high antimicrobial susceptibility to vancomycin and teicoplanin.Resistance rates of Entero-coccus faecalis and Enterococcus faecium to vancomycin present decreased trends.

Objective To analyze the distribution and changing trend of antimicrobial resistance of bacteria isolated from bile from Hunan Province Antimicrobial Resistance Surveillance System.Methods Data of pathogens isolated from bile from Hunan Province Antimicrobial Resistance Surveillance System from 2012 to 2021 were collected.The constituent of bacteria and antimicrobial susceptibility testing results were analyzed by WHONET 5.6 software.Changes in antimicrobial resistance was analyze by trend chi-square test.Results The major pathogenic bacteria isolated from bile were Gram-negative bacteria,accounting for 70.84％.The top three isolated Gram-negative pathogens were Escherichia coli(30.14％),Klebsiella pneumoniae(12.15％),and Pseudomonas aeruginosa(5.18％),and the top two Gram-positive bacteria were Enterococcus faecium(10.34％)and Enterococcus faecalis(9.52％).The resistance rates of Klebsiella pneumoniae and Escherichia coli to imipenem were highest in 2012-2013,being 15.7％and 14.9％,respectively,presenting an downward trend(P＜0.05);resistance rates to piperacillin/tazobactam and cefoperazone/sulbactam were＜24％,presenting an upward trend year by year(P＜0.05);the sus-ceptibility rate to amikacin was＞94％,to levofloxacin and ciprofloxacin was 15.5％-65.2％.The highest resis-tance rate of Pseudomonas aeruginosa to imipenem(32.0％)was higher than that of meropenem(22.9％),resis-tance rates to piperacillin/tazobactam and cefoperazone/sulbactam were＜19％.The highest resistance rates of Acinetobacter baumannii to imipenem and meropenem were 59.4％and 62.6％,respectively,resistance rate to cefo-perazone/sulbactam was＜48％,presenting an upward trend(P＜0.05);the highest resistance rate to ciprofloxa-cin(60.8％)was higher than levofloxacin(48.7％);resistance rate to tigecycline was＜8％.The resistance rates of Enterococcus faecium to penicillin and ampicillin were both higher than those of Enterococcus faecalis,presenting an upward trend(P＜0.05).Resistance rate of Enterococcus faecium to vancomycin was lower than that of Entero-coccus faecalis.The resistance rates of Enterococcus faecium to vancomycin and linezolid were 0.5％-4.5％and 0.5％-3.4％,respectively;resistance rates of Enterococcus faecalis to vancomycin and linezolid were 0.2％-1.7％and 0.5％-3.5％,respectively(both P＜0.05),all presenting a downward trend(all P＜0.05).Conclusion Pathogenic bacteria isolated from bile are mainly related to the intestinal flora.The resistance rates of Enterococcus faecalis and Enterococcus faecium to vancomycin and linezolid as well as resistance rate of Enterobacterales to car-bapenem antibiotics all present a downward trend.

Objective To understand the antimicrobial resistance of Escherichia spp.from member units of Hu-nan Province Antimicrobial Resistance Surveillance System from 2012 to 2021.Methods According to the technical scheme of China Antimicrobial Resistance Surveillance System(CARSS),data about Escherichia spp.and the anti-microbial susceptibility testing results reported from member units of Hunan Province Antimicrobial Resistance Sur-veillance System were analyzed by WHONET 5.6 software.Results From 2012 to 2021,a total of 476 351 clini-cally isolated Escherichia spp.were collected,475 520 of which were Escherichia coli,accounting for 99.8％;92.6％were isolated from inpatients;39.3％were isolated from urine specimens.Over the past 10 years,the proportion of Escherichia spp.in total detected pathogens remained relatively stable,ranging 20％-23％,the lowest rate was 18.7％in 2012,and the highest rate was 22.9％in 2015.In the past 10 years,the resistance rates of Escherichia spp.to ampicillin,ceftriaxone,cefotaxime and ampicillin/sulbactam were＞80％,＞47％,＞45％,and＞39％,respectively;resistance rates to piperacillin/tazobactam,cefoperazone/sulbactam,and nitrofurantoin were all＜8％,to tigecycline,amikacin,imipenem,and meropenem(except in 2012)were all＜5％.Resistance of Escherichia spp.to 22 commonly clinically used antimicrobial agents fluctuated,but overall trend decreased year by year.The resistance rates of Escherichia spp.from patients in the intensive care unit(ICU),non-ICU patients,outpatients,and emergency patients to 22 clinically commonly used antimicrobial agents were compared among different depart-ments,and the differences were statistically significant(all P＜0.05).The resistance rates of Escherichia spp.iso-lated from ICU and non-ICU patients were compared,and except for tigecycline,the resistance rates to the other 21 antimicrobial agents were statistically different(all P＜0.05).The resistance rates of Escherichia spp.isolated from patients to commonly clinically used antimicrobial agents were statistically different among patients of different age groups(all P＜0.05).Conclusion Escherichia spp.isolated from patients in different years,departments,specimens,and ages have different resistance to commonly used antimicrobial agents.It is necessary to continue to strengthen the surveillance on bacterial resistance,so as to guide the rational choice of antimicrobial agents.

Objective To observe and compare the changes of vertebral bone mineral density(BMD)in the early stages of spinal Mycobacterium tuberculosis infection.Methods Patients who underwent spinal surgery at Xiangya Hospital,Central South University from January 1 to December 31,2023 were continuously enrolled(spinal tuber-culosis group),based on gender matching,non-spinal tuberculosis surgical patients treated for spinal stenosis were selected as the control group.Dual-energy X-ray scans were performed on the enrolled patients,difference in verte-bral BMD between two groups of patients was compared.An animal model of spinal Mycobacterium tuberculosis in-fection(referred to as the animal model)was constructed,differences in microstructure of trabecular bone between spinal tuberculosis group and control group was compared,and the bone volume/tissue volume(BV/TV),the thickness of trabecular bone(Tb.Th),the number of trabecular bone(Tb.N),and sparse density of trabecular(Tb.Sp)were used as evaluation indexes to further analyze the bone quality differences between the diseased verte-brae and the neighboring vertebrae.Results 69 patients were included in the spinal tuberculosis group and the con-trol group,respectively.The BMD of patients in the spinal tuberculosis group(0.793[0.712,0.869]g/cm2)was lower than that of the control group(0.907[0.800,1.020]g/cm2),difference was statistically significant(P＜0.05).Microstructure of trabecular bone BV/TV([18.4±5.4]％),Tb.Th([0.124±0.010]mm)in the spinal tuberculosis group of animal model were significantly altered compared with BV/TV([22.6±3.2]％),Tb.Th([0.160±0.017]mm)in the control group(both P＜0.05).In the spinal tuberculosis group,microstructure of diseased vetebral trabecular bone BV/TV([25.5±6.7]％)and Tb.N([1.871±0.443]/mm)were significantly lower than BV/TV([26.6±6.8]％)and Tb.N([1.969±0.454]/mm)in the neighboring vertebrae,both with statistically difference(both P＜0.05).Conclusion In the early stages of spinal Mycobacterium tuberculosis infec-tion,microstructure of vertebral trabecular bone can be altered,leading to a decrease in BMD.

Objective To monitor the susceptibility of clinical isolates to antimicrobial agents in tertiary hospitals in major regions of China in 2022.Methods Clinical isolates from 58 hospitals in China were tested for antimicrobial susceptibility using a unified protocol based on disc diffusion method or automated testing systems.Results were interpreted using the 2022 Clinical &Laboratory Standards Institute(CLSI)breakpoints.Results A total of 318 013 clinical isolates were collected from January 1,2022 to December 31,2022,of which 29.5％were gram-positive and 70.5％were gram-negative.The prevalence of methicillin-resistant strains in Staphylococcus aureus,Staphylococcus epidermidis and other coagulase-negative Staphylococcus species(excluding Staphylococcus pseudintermedius and Staphylococcus schleiferi)was 28.3％,76.7％and 77.9％,respectively.Overall,94.0％of MRSA strains were susceptible to trimethoprim-sulfamethoxazole and 90.8％of MRSE strains were susceptible to rifampicin.No vancomycin-resistant strains were found.Enterococcus faecalis showed significantly lower resistance rates to most antimicrobial agents tested than Enterococcus faecium.A few vancomycin-resistant strains were identified in both E.faecalis and E.faecium.The prevalence of penicillin-susceptible Streptococcus pneumoniae was 94.2％in the isolates from children and 95.7％in the isolates from adults.The resistance rate to carbapenems was lower than 13.1％in most Enterobacterales species except for Klebsiella,21.7％-23.1％of which were resistant to carbapenems.Most Enterobacterales isolates were highly susceptible to tigecycline,colistin and polymyxin B,with resistance rates ranging from 0.1％to 13.3％.The prevalence of meropenem-resistant strains decreased from 23.5％in 2019 to 18.0％in 2022 in Pseudomonas aeruginosa,and decreased from 79.0％in 2019 to 72.5％in 2022 in Acinetobacter baumannii.Conclusions The resistance of clinical isolates to the commonly used antimicrobial agents is still increasing in tertiary hospitals.However,the prevalence of important carbapenem-resistant organisms such as carbapenem-resistant K.pneumoniae,P.aeruginosa,and A.baumannii showed a downward trend in recent years.This finding suggests that the strategy of combining antimicrobial resistance surveillance with multidisciplinary concerted action works well in curbing the spread of resistant bacteria.