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 compare five time series models and predict the monthly incidence of bacillary dysentery in Qinghai Province in 2024,and provide reference for the prevention and control.Methods The epidemic charac-teristics of bacterial dysentery in Qinghai Province from 2014 to 2023 were analyzed.R4.3.1 software was used for establishing seasonal autoregressive integrated moving average(SARIMA)model,Holt-Winters triple exponential smoothing(Holt Winters)model,exponential smoothing(ETS)model,neural network autoregression(NNAR)model,and trigonometric seasonality,Box-Cox transformation,ARMA errors,trend and seasonal components(TBATS)model.Fitting effect of the models was analyzed and accuracy was compared.Results From 2014 to 2023,a total of 5 833 cases of bacterial dysentery were reported in Qinghai Province,without deaths,male to fe-male ratio being 1.23∶1.The highest incidence was reported in 2016(15.45 per 100 000 people),and the lowest in-cidence was reported in 2023(3.68 per 100 000 people).Incidence increased from 2014 to 2016,then decreased,showing an obvious overall downward trend.Case number in＜5 years age group was the highest,accounting for 29.76％of the total cases(n=1 736).Regarding population distribution,the top three were children in childcare institutions and scattered children(35.56％),farmers(24.65％),and students(12.62％).Except the additive Holt-Winters model,the predicted trends of the other four models were consistent with actuality.The ETS model had the best fitting effect,with a relatively balanced overall performance(training set:MAE=0.13,RMSE=0.21,MAPE=19.55％;testing set:MAE=0.11,RMSE=0.16,MAPE=28.66％).It is recommended to pre-dict the incidence of bacillary dysentery in Qinghai Province based on ETS model.Conclusion From 2014 to 2023,bacterial dysentery in Qinghai Province showed a downward trend,with the peak of the epidemic from June to Au-gust.Preschool and scattered children were high-risk groups.Among the five prediction models,ETS model has the best fitting effect,and can be used to predict the incidence of bacillary dysentery.

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.

Objective:To investigate the genomic characteristics of a clinical strain of respiratory syncytial virus (RSV) causing a severe pneumonia outbreak in a maternity center in a city in northern China in 2021.Methods:The whole genome sequence of RSV from a clinical sample obtained from a child with respiratory failure and heart failure was determined and analyzed using Sanger sequencing method. Sequence splicing and alignment were performed using bioinformatics software such as Sequencher 5.0, MEGA 7.0, and BioEdit 7.0. Besides, its phylogenetic relationship with the representative strains of RSV-B genotype, amino acid variations, and glycosylation sites were analyzed.Results:The genome of the clinical strain (named RSV/SY/2021) was 15 242 bp in length, consisting of 10 genes encoding 11 proteins, and possessed all the structural features of RSV. Phylogenetic analysis showed that the RSV/SY/2021 strain belonged to BA9 genotype and had the closest genetic relationship with the 2018 Netherlands epidemic strain MZ515558/Netherlands/2018. The termination codon mutation at the end of its attachment glycoprotein (G) gene resulted in the elongation of seven amino acids "Q-R-L-Q-S-Y-A" and the introduction of two additional O-glycosylation sites.Conclusions:This study suggests that RSV BA9 genotype may cause severe clinical symptoms, and clarifies the genome-wide characteristics and nucleotide/amino acid variation patterns of the RSV/SY/2021 strain. These findings enrich both national and global genome databases of RSV, and provide crucial etiological data for tracking RSV transmission, nucleic acid testing, and the development and evaluation of vaccines, antibodies and drugs against RSV.

Objective To investigate the distribution and antimicrobial resistance profiles of clinically isolated Haemophilus influenzae and Moraxella catarrhalis in hospitals across China from 2015 to 2021,and provide evidence for rational use of antimicrobial agents.Methods Data of H.influenzae and M.catarrhalis strains isolated from 2015 to 2021 in CHINET program were collected for analysis,and antimicrobial susceptibility testing was performed by disc diffusion method or automated systems according to the uniform protocol of CHINET.The results were interpreted according to the CLSI breakpoints in 2022.Beta-lactamases was detected by using nitrocefin disk.Results From 2015 to 2021,a total of 43 642 strains of Haemophilus species were isolated,accounting for 2.91％of the total clinical isolates and 4.07％of Gram-negative bacteria in CHINET program.Among the 40 437 strains of H.influenzae,66.89％were isolated from children and 33.11％were isolated from adults.More than 90％of the H.influenzae strains were isolated from respiratory tract specimens.The prevalence of β-lactamase was 53.79％in H.influenzae strains.The H.influenzae strains isolated from children showed higher resistance rate than the strains isolated from adults.Overall,779 strains of H.influenzae did not produce β-lactamase but were resistant to ampicillin(BLNAR).Beta-lactamase-producing strains showed significantly higher resistance rates to these antimicrobial agents than the β-lactamase-nonproducing strains.Of the 16 191 M.catarrhalis strains,80.06％were isolated from children and 19.94％isolated from adults.M.catarrhalis strains were mostly susceptible to both amoxicillin-clavulanic acid and cefuroxime,evidenced by resistance rate lower than 2.0％.Conclusions The emergence of antibiotic-resistant H.influenzae due to β-lactamase production poses a challenge for clinical anti-infective treatment.Therefore,it is very important to implement antibiotic resistance surveillance for H.influenzae and guide rational antibiotic use.All local clinical microbiology laboratories should actively improve antibiotic susceptibility testing and strengthen antibiotic resistance surveillance for H.influenzae.

Objective To investigate the changing antibiotic resistance profiles of E.coli isolated from patients in the 52 hospitals participating in the CHINET program from 2015 to 2021.Methods Antimicrobial susceptibility was tested for clinical isolates of E.coli according to the unified protocol of CHINET program.WHONET 5.6 and SPSS 20.0 software were used for data analysis.Results Atotal of 289 760 nonduplicate clinical strains ofE.coli were isolated from 2015 to 2021,mainly from urine samples(44.7±3.2)％.The proportion of E.coli strains isolated from urine samples was higher in females than in males(59.0％vs 29.5％).The proportion of E.coli strains isolated from respiratory tract and cerebrospinal fluid samples was significantly higher in children than in adults(16.7％vs 7.8％,0.8％vs 0.1％,both P＜0.05).The isolates from internal medicine department accounted for the largest proportion(28.9±2.8)％with an increasing trend over years.Overall,the prevalence of ESBLs-producing E.coli and carbapenem resistant E.coli(CREco)was 55.9％and 1.8％,respectively during the 7-year period.The prevalence of ESBLs-producing E.coli was the highest in tertiary hospitals each year from 2015 to 2021 compared to secondary hospitals.The prevalence of CREco was higher in children's hospitals compared to secondary and tertiary hospitals each year from 2015 to 2021.The prevalence of ESBLs-producing E.coli in tertiary hospitals and children's hospitals and the prevalence of CREco in children's hospitals showed a decreasing trend over the 7-year period.The prevalence of CREco in secondary and tertiary hospitals increased slowly.Antibiotic resistance rates changed slowly from 2015 to 2021.Carbapenem drugs(imipenem,meropenem)were the most active drugs amongβ-lactams against E.coli(resistance rate≤2.1％).The resistance rates of E.coli to β-lactam/β-lactam inhibitor combinations(piperacillin-tazobactam,cefoperazone-sulbactam),aminoglycosides(amikacin),nitrofurantoin and fosfomycin(for urinary isolates only)were all less than 10％.The resistance rate of E.coli strains to antibiotics varied with the level of hospitals and the departments where the strains were isolated,especially for cefazolin and ciprofloxacin,to which the resistance rate of E.coli strains from children in non-ICU departments was significantly lower than that of the strains isolated from other departments(P＜0.05).The E.coli isolates from ICU showed higher resistance rate to most antimicrobial agents tested(excluding tigecycline)than the strains isolated from other departments.The E.coli strains isolated from tertiary hospitals showed higher resistance rates to the antimicrobial agents tested(excluding tigecycline,polymyxin B,cefepime and carbapenems)than the strains from secondary hospitals and children's hospitals.Conclusions E.coli is an important pathogen causing clinical infection.More than half of the clinical isolates produced ESBL.The prevalence of CREco is increasing in secondary and tertiary hospitals over the 7-year period even though the overall prevalence is still low.This is an issue of concern.

Objective:To investigate the genomic characteristics of a clinical strain of respiratory syncytial virus (RSV) causing a severe pneumonia outbreak in a maternity center in a city in northern China in 2021.Methods:The whole genome sequence of RSV from a clinical sample obtained from a child with respiratory failure and heart failure was determined and analyzed using Sanger sequencing method. Sequence splicing and alignment were performed using bioinformatics software such as Sequencher 5.0, MEGA 7.0, and BioEdit 7.0. Besides, its phylogenetic relationship with the representative strains of RSV-B genotype, amino acid variations, and glycosylation sites were analyzed.Results:The genome of the clinical strain (named RSV/SY/2021) was 15 242 bp in length, consisting of 10 genes encoding 11 proteins, and possessed all the structural features of RSV. Phylogenetic analysis showed that the RSV/SY/2021 strain belonged to BA9 genotype and had the closest genetic relationship with the 2018 Netherlands epidemic strain MZ515558/Netherlands/2018. The termination codon mutation at the end of its attachment glycoprotein (G) gene resulted in the elongation of seven amino acids "Q-R-L-Q-S-Y-A" and the introduction of two additional O-glycosylation sites.Conclusions:This study suggests that RSV BA9 genotype may cause severe clinical symptoms, and clarifies the genome-wide characteristics and nucleotide/amino acid variation patterns of the RSV/SY/2021 strain. These findings enrich both national and global genome databases of RSV, and provide crucial etiological data for tracking RSV transmission, nucleic acid testing, and the development and evaluation of vaccines, antibodies and drugs against RSV.

AIM:To investigate the impact of Kir2.1 channels on abnormal spontaneous pacemaker activities induced by hypokalemia and to elucidate the underlying mechanisms.METHODS:Human induced pluripotent stem cell-derived cardiomyocytes(hiPSC-CMs)were transfected with lentiviral particles containing sequences for human Kir2.1,the Kir2.1-E224G mutant,or Kir4.1.Patch clamp techniques were employed to examine the effects of low extracellular potassium concentration([K+]e)of 1 mmol/L on the resting membrane potentials and whole-cell currents of the cells in each group,assessed via both current and voltage clamp modes.RESULTS:Under conditions of 1 mmol/L[K+]e,cur-rent clamp data revealed that hiPSC-CMs overexpressing Kir2.1 channels exhibited both hyperpolarized and depolarized resting membrane potentials,with the depolarized state triggering abnormal pacemaker activities.In contrast,cells overex-pressing the Kir2.1-E224G mutant or Kir4.1 channels displayed only hyperpolarized resting membrane potentials.Voltage clamp analysis indicated that hiPSC-CMs overexpressing Kir2.1 channels produced"N"-shaped whole-cell currents,whereas cells expressing the Kir2.1-E224G mutant or Kir4.1 exhibited typical K+currents.CONCLUSION:Kir2.1 channels play a crucial role in mediating hypokalemia-induced abnormal spontaneous pacemaker activities in human car-diomyocytes through their inward rectification properties.

Objective:To study and establish the quality standard of Polyoxyl 15 hydroxystearate(HS15),a phar-maceutical excipient,and systematically evaluate its functionality-related characteristics and safety.HS15 was applied to the preparation of docetaxel(DTX)injection to further investigate the safety and pharmacokinetic char-acteristics of the injection in vitro and in vivo.Methods:Based on the general USP-NF2024,EP11.0 and the fourth general rules of the Chinese Pharmacopoeia 2020 edition,the quality standards of HS15 were studied.Combined with the functional properties of surfactants,the critical micelle concentration of HS15 was investigated,and its safety was investigated by hemolysis test and vascular irritation test in vitro.HS15 was further applied to the preparation of DTX injection,and the safety and efficacy of the preparation were comprehensively evaluated by in vitro cytotoxicity test and in vivo pharmacokinetic study.Results:According to the experimental results and the pharmacopoeia of various countries,the quality standard of HS15 was preliminarily formulated.When the concen-tration of HS15 was 1 mg·mL-1,the hemolysis rate was about0.2%,the vascular irritation was small,and the DTX injection was safe in vitro and in vivo.The pharmacokinetic behavior was in line with expectations.Conclusion:This study successfully established the quality standard of HS15,and its functional correlation index research and safety evaluation strategy can provide reference for the quality control of similar excipients.The appli-cation of HS15 in the preparation of DTX injection provides a theoretical and experimental basis for its application in the development of insoluble antitumor drug injection.