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 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 evaluate the clinical efficacy of percutaneous balloon pulmonary valvuloplasty (PBPV) via antegrade venous-arterial loop in neonates with critical pulmonary stenosis with intact ventricular septum (CPS-IVS).Methods:A retrospective case review was conducted. Fifteen neonates with CPS-IVS who underwent PBPV via antegrade venous-arterial loop at the Women and Children′s Hospital, Qingdao University between September 2020 and September 2023 were included. Pre-and post-operative right ventricular functional parameters, surgical complications, and follow-up outcomes were analyzed. Paired-sample t-test was used to compare changes in right ventricular systolic pressure (RVSP), percutaneous oxygen saturation (SpO 2), and echocardiographic findings pre-and post-operatively, as well as during the follow-up period. Results:Among the 15 neonates (9 males and 6 females) with CPS-IVS, the surgical age was (3.6±0.5) d. All neonates underwent successful PBPV via antegrade venous-arterial loop under general anesthesia. The immediate post-operative trans-pulmonary valve pressure gradient was (35±6) mmHg (1 mmHg=0.133 kPa), with a significant reduction in RVSP from (96±16) mmHg to (59±14) mmHg ( t=6.70, P<0.001). SpO 2 (with an inspired oxygen concentration of 0.48) increased from 0.86±0.07 pre-operatively to 0.97±0.03 post-operatively ( t=4.81, P<0.001). One month postoperatively, SpO 2 (without oxygen supplementation) normalized in all patients, with a statistically significant difference compared to pre-operative values ( t=0.16, P<0.001). Immediately postoperative, mild to moderate diastolic pulmonary valve regurgitation was observed in 8 patients, with no cases of severe regurgitation. Additionally, the severity of tricuspid valve regurgitation decreased from severe to mild-to-moderate in 6 patients. Three months postoperatively, one patient underwent a second PBPV due to an increased trans-pulmonary valve pressure gradient of 74 mmHg, which decreased to 27 mmHg immediately after the procedure, with subsequent good recovery. Over a one-year follow-up period, all 15 patients demonstrated improvements in right ventricular indices. The Z-score of the tricuspid valve annulus significantly improved from -1.9±0.8 pre-operatively to -0.4±0.1 post-operatively ( t=6.88, P<0.001). At the last follow-up, mild to moderate pulmonary valve regurgitation was observed in 3 patients, and mild tricuspid regurgitation in 2 patients, with no cases of moderate or severe regurgitation. Conclusion:Intervention via antegrade venous-arterial loop for the treatment of CPS-IVS in neonates is safe and effective.

Objective:To investigate the feasibility of ductus arteriosus (DA) stent placement through femoral artery approach without guiding catheter.Methods:In this retrospective case study, the birth weight, intervention age, preoperative echocardiography, intraoperative angiography and other clinical data, as well as the follow-up status (Nakata index and final circulatory status, etc.) of 15 patients with congenital heart disease who are dependent on the DA for pulmonary circulation at Women and Children′s Hospital, Qingdao University between January 2018 to June 2023 were collected. All pediatric patients underwent placement of a DA stent without a guiding catheter, the efficacy and safety of this approach were analyzed.Results:Among all 15 cases, there were 9 males and 6 females, with the birth weight of (3.3±0.3) kg and the intervention age of (15.0±0.1) d. Of which, there were 9 cases of pulmonary atresia with intact ventricular septum (PA-IVS), and 6 cases of critical pulmonary stenosis (CPS) with intact ventricular septum. The tricuspid annulus diameter before intervention was (8.8±0.8) mm, and the tricuspid annulus Z-score was -0.7±0.9. There were 3 cases of mild right ventricular dysplasia, 9 cases of moderate dysplasia, and 3 cases of severe dysplasia. All patients successfully completed the intervention without major complications. The narrowest diameter of the DA was (2.2±0.1) mm, the diameter of the DA stent was (3.9±0.3) mm, the preoperative percutaneous oxygen saturation (SpO 2) was 0.83±0.03, and the postoperative SpO 2 was 0.96±0.02. The follow-up time was (7.0±0.5) months. The Nakata index was (163±30) mm 2/m 2 before intervention, and was (173±34) mm 2/m 2 at the last follow-up. Biventricular circulation was successfully achieved in 14 patients, and the other one patient currently under close observation. Conclusion:The placement of a ductus arteriosus stent through femoral artery retrogradely without guiding catheter could serve as an effective and safe plan for neonates with PA-IVS or CPS accompanied by hypoplastic right heart syndrome.

Objective:To evaluate the clinical characteristics and prognosis of transcatheter closure of secundum atrial septal defect (ASD) in infants.Methods:A retrospective analysis was conducted on 83 cases with secundum ASD who underwent transcatheter closure at the Women and Children′s Hospital of Qingdao University from January 2010 to December 2021. The clinical data included general information, pre- and post-operative echocardiography and electrocardiography, surgery records, and follow-up outcomes. The children who underwent successful occlusion were divided into two groups based on the presence or absence of pulmonary hypertension: the normal group and the pulmonary hypertension group. Differences between the two groups in terms of age, weight, right ventricular end-diastolic diameter, maximum ASD diameter, occluder size, and pulmonary-to-systemic flow ratio (Qp/Qs) were compared. Intergroup comparisons were performed using the Wilcoxon test.Results:Among the 83 infants with secundum ASD, 12 were males and 71 were females, with the age of (10.8±1.6) months. There were 29 cases (35%) with weight-for-age below the median level (less than the 25th percentile), 19 cases (23%) with recurrent or refractory pulmonary infections, and 40 cases (48%) with pulmonary hypertension. In this study, 81 cases (97%) successfully completed the procedure, while 2 cases failed due to soft defect margins. Postoperative arrhythmias occurred in 12 cases, of which 11 were transient arrhythmia; one case of atrioventricular block returned to normal rhythm after surgical removal of the occluder. The 81 infants who underwent successful occlusion were divided into normal group (41 cases) and pulmonary hypertension group (40 cases). The pulmonary artery systolic pressure, maximum diameter of ASD, the size of the occluder, and the cardiothoracic ratio were higher in the pulmonary hypertension group compared to those in the normal group, while the Qp/Qs value was lower (all P<0.05). Follow-up results indicated that infants with ASD who underwent transcatheter closure had no new arrhythmias, residual shunts, or intervention-related mortality. Within one year postoperatively, all infants exhibited normalization of right ventricular dimensions and pulmonary artery pressure. During a 3-year follow-up, all 29 cases that originally had a weight-for-age below the median level exhibited catch-up growth, reaching above the median level. Conclusions:Transcatheter closure for secundum ASD in infants is safe and feasible. Follow-up indicates that early transcatheter closure may be necessary for larger ASD diameters combined with pulmonary hypertension, with significant clinical improvement postoperatively.

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 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 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.