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 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.

Enterobacterales are important pathogens responsible for hospital-acquired infections and can cause various severe infectious diseases. Since their first report, extended-spectrum β-lactamase-producing Enterobacterales(ESBL-E) have become widely prevalent worldwide. These strains often exhibit multidrug resistance, significantly increasing the risk of treatment failure and patient mortality. In China, the prevention and control of ESBL-E face numerous challenges, including high prevalence rates, significant regional distribution disparities, uneven laboratory testing capabilities, and variations in antimicrobial stewardship and prescribing practices. To address these issues, Professors Zhuo Chao, Xu Yingchun and Yu Yunsong initiated the developmentof the Expert Consensus on Clinical Management Strategies for Infections Caused by Extended-Spectrum β-Lactamase-Producing Enterobacterales (2025), in collaboration with multidisciplinary experts. This consensus systematically reviews the global and domestic epidemiological characteristics of ESBL-E, clinical laboratory detection techniques, treatment principles and key therapeutic agents, as well as infection prevention and control measures. Furthermore, it elaborates on the microbiological features and stratified treatment strategies for different infection sources (including bloodstream infections, intracranial infections, respiratory and mediastinal infections, intra-abdominal infections, and urinary tract infections) and special populations (such as neutropenic patients with fever, emergency patients, and pediatric patients). The consensus aims to enhance the detection capacity of clinical laboratories for ESBL-E, standardize diagnosis and treatment strategies in healthcare settings, and provide scientific guidance to curb the spread of ESBL-E in China, thereby reducing associated morbidity and mortality.

Objective To analyze the epidemiological characteristics of acute respiratory infections(ARIs)during the autumn-winter season in Beijing,providing evidence for the prevention,control,diagnosis,and treatment of ARIs.Methods A convenience sampling method was employed,enrolling patients who visited Peking Union Medical College Hospital(PUMCH)between September 2023 and February 2024 due to ARIs.Na-sopharyngeal swabs were collected,and real-time fluorescence quantitative PCR was used to detect six common respiratory pathogens[influenza A virus(FluA),influenza B virus(FluB),human rhinovirus(HRV),Myco-plasma pneumoniae(MP),respiratory syncytial virus(RSV),and adenovirus(ADV)],as well as SARS-CoV-2 infection.The distribution patterns of pathogen infections were analyzed.Results A total of 5556 eligible patients were included.The overall positivity rate for the six common respiratory pathogens was 63.7％,with sin-gle-pathogen positivity at 54.0％,dual-pathogen positivity at 8.9％,and triple or more pathogen positivity at 0.7％.The predominant pathogens detected were FluA(16.1％)and RSV(15.7％),followed by ADV(11.1％),MP(11.1％),HRV(10.0％),and FluB(10.0％).No significant difference in overall pathogen positivity was observed between genders.However,significant differences were found between autumn and winter(x2=34.617,P＜0.001)and among pediatric,young/middle-aged,and elderly patients(x2=422.38,P＜0.001).Specifically,MP(x2=8.647,P=0.003),FluA(x2=131.932,P＜0.001),and HRV(x2=174.199,P＜0.001)exhibited significantly higher positivity rates in autumn than in winter,whereas FluB was more prevalent in winter(x2=287.894,P＜0.001).In pediatric patients,MP,RSV,HRV,and ADV positivity rates were significantly higher than in young/middle-aged and elderly patients(all P＜0.001),whereas FluB was more common in young/middle-aged patients(both P＜0.001).The positivity rates of the six common respiratory pathogens significantly declined during the SARS-CoV-2 epidemic period,exhibiting an asynchronous seasonal pattern.Conclusions The prevalence of respiratory pathogens in Beijing is associated with age and season.Tar-geted preventive measures should be implemented in different seasons and for key populations.

Objective To analyze the main epidemiological characteristics of fungal infection in this hospital in the past 7 years,and to provide reference for clinical treatment and prevention and control strategies of fun-gal infection.Methods The fungal data and clinical data of related patients isolated from clinical samples in Peking Union Medical College Hospital from early January 2018 to the end of May 2024 were selected,and the main epidemiological characteristics of fungal infection in this hospital were identified and described through multi-angle statistical analysis.Results A total of 4 479 patients with filamentous fungal infection were en-rolled.The proportion of male patients[57.5％(2 576/4 479)]was higher than that of female patients[42.5％(1 903/4 143)],mainly distributed in internal medicine,Intensive Care Unit(ICU)and emergency de-partment,among which internal medicine accounted for the highest proportion[50.0％(2 241/4 479)].About 90.0％of the specimens were from the lower respiratory tract,in addition to specimens from skin and soft tis-sue,tissue,ear and blood culture.In terms of seasonal distribution,there are more patients in winter.The fun-gi were mainly composed of Aspergillus,Mucor,Cerdosporium,Fusarium and Penicillium,among which As-pergillus was the most abundant,accounting for 74.6％of the total.Aspergillus fumigatus was the most a-bundant Aspergillus,accounting for 42.5％of the total Aspergillus(1 418/3 340).Among the related infec-tions caused by mold,Aspergillus was the most common in the lower respiratory tract,accounting for 76.8％.Among them,Aspergillus fumigatus accounted for the highest proportion(33.6％).98.6％of the molds infected the ear were Aspergillus,of which Aspergillus niger and Aspergillus terreus were the most common.Skin infections are mainly caused by Sporothrix schenckii,Trichophyton rubrum,Microsporum ca-nis.The results of in vitro drug sensitivity test showed that the four common Aspergillus isolated in this hos-pital were sensitive to voriconazole,and amphotericin B had better antifungal activity against Mucorales in vitro.Conclusion Based on the main epidemiological characteristics of fungal infections in this hospital,it is recommended that special attention be paid to the admission of patients in the respiratory department during the peak infection period in autumn and winter.In the treatment of fungal infections in different regions and on different body parts,attention should be paid to the differences in the distribution of bacterial species.

A 62-year-old male, was admitted to the hospital, with a chief complaint of fever lasting over 10 days and leukopenia and thrombocytopenia for 2 days. Ten days prior to admission, the patient experienced intermittent fever without obvious incentive factors. The breath sounds in both lungs were coarse, without accompanying dry or moist rales. Color Doppler Ultrasound indicated mild splenomegaly and multiple lymphadenectasis in the bilateral cervical, axillary, and inguinal regions. Morphological examination of bone marrow cells demonstrated abnormally large blasts, with some of the nuclei being rather irregular and cytoplasmic vacuoles. Immunophenotyping results identified this group of blast cells as immature monocytes. Karyotype analysis of chromosomes showed clonal abnormalities, with 19 out of 20 cells exhibiting near-tetraploid karyotypes, including complex karyotypic abnormalities involving chromosome17.Targeted next-generation sequencing (NGS) detected gene mutations associated with hematological malignancies that have definite or potential clinical significance,including TP53, SRSF2, STAG2, and ARID2, with variant allele frequencies (VAF) of 63.10%, 30.30%, 0.80%, and 0.60%, respectively. Integrating laboratory findings, the diagnosis was diagnosed as AML-M5 at high-risk. After receiving chemotherapy with the regimen of azacitidine combined with venetoclax, the patient passed away more than 20 days later.

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.