Objective To monitor the susceptibility of clinical isolates to antimicrobial agents in healthcare facilities in major regions of China in 2023. Methods Clinical isolates collected from 73 hospitals across China were tested for antimicrobial susceptibility using a unified protocol based on disc diffusion method or automated testing systems. Results were interpreted using the 2023 Clinical & Laboratory Standards Institute (CLSI) breakpoints. Results A total of 445 199 clinical isolates were collected in 2023, of which 29.0% were gram-positive and 71.0% 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) (MRSA, MRSE and MRCNS) was 29.6%, 81.9% and 78.5%, respectively. Methicillin-resistant strains showed significantly higher resistance rates to most antimicrobial agents than methicillin-susceptible strains (MSSA, MSSE and MSCNS). Overall, 92.9% of MRSA strains were susceptible to trimethoprim-sulfamethoxazole and 91.4% of MRSE strains were susceptible to rifampicin. No vancomycin-resistant strains were found. Enterococcus faecalis had 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 93.1% in the isolates from children and and 95.9% in the isolates from adults. The resistance rate to carbapenems was lower than 15.0% for most Enterobacterales species except for Klebsiella, 22.5% and 23.6% of which were resistant to imipenem and meropenem, respectively . Most Enterobacterales isolates were highly susceptible to tigecycline, colistin and polymyxin B, with resistance rates ranging from 0.6% to 10.0%. The resistance rate to imipenem and meropenem was 21.9% and 17.4% for Pseudomonas aeruginosa, respectively, and 67.5% and 68.1% for Acinetobacter baumannii, respectively. Conclusions Increasing resistance to the commonly used antimicrobial agents is still observed in clinical bacterial isolates. However, the prevalence of important crabapenem-resistant organisms such as crabapenem-resistant K. pneumoniae, P. aeruginosa, and A. baumannii showed a slightly decreasing trend. This finding suggests that strengthening bacterial resistance surveillance and multidisciplinary linkage are important for preventing the occurrence and development of bacterial resistance.

Objective To evaluate the efficacy and safety of eravacycline in the treatment of complicated intra-abdominal infection (cIAI) in Chinese adult patients. Methods In this multicenter, randomized, double-blind phase III study, cIAI patients were randomly assigned to receive either eravacycline (1.0 mg/kg, q12h) or ertapenem (1 g, q24h) by intravenous infusion for 5 to 14 days. The primary and secondary efficacy endpoints included the clinical efficacy and microbiological efficacy in different populations, including modified intention-to-treat (MITT) population, clinically evaluable (CE) population, and microbiologically evaluable (ME) population, at different time points after treatment. Clinical cure rates at specific visits were summarized and compared between treatment groups in different populations. The microbial eradication rate was calculated for the patients with baseline pathogens. The incidence of adverse events (AE) and drug-related treatment emergent adverse event (TEAE) was analyzed by treatment group. Results A total of 144 patients with cIAI who received at least one dose of the study drug were included in the MITT population. The clinical cure rate was 77.8% (56/72) in eravacycline-treated patients and 90.3% (65/72) in ertapenem-treated patients at 25-31 days after the first dose (TOC visit). When the patients who received insufficient treatment (< 72 hours) were excluded, the clinical cure rate was 83.6% (56/67) in eravacycline group and 90.3% (65/72) in ertapenem. For CE and ME patients, the clinical cure rate at TOC visit was 91.1% (51/56) and 83.3% (25/30) in eravacycline group, 95.3% (61/64) and 90.9% (30/33) in ertapenem group. Eravacycline treatment achieved microbiological eradication rate of 91.3% (21/23) against Escherichia coli at TOC visit in micro-MITT population while ertapenem treatment resulted in a microbiological eradication rate of 96.2% (25/26). The microbiological efficacy of eravacycline and ertapenem against Klebsiella pneumoniae was 4/5 and 3/3, respectively. The incidence of TEAE was similar in eravacycline and ertapenem groups (75.0% vs.70.8%), most of which were mild or moderate. The AEs associated with eravacycline were mainly infusion site phlebitis (9.7%, 7/72) and infusion site pain (8.3%, 6/72). Conclusions Similar to ertapenem, eravacycline has good clinical and microbiological efficacy in treating cIAI. It is also safe and well-tolerated in the patients.

碳青霉烯类耐药革兰阴性菌（CRGNB）的广泛播散是一个全球性的公共卫生问题。CRGNB临床分离株通常呈现广泛耐药或全耐药,对其感染的抗菌治疗方案有限、死亡率高。由感染病临床诊疗、临床微生物、临床药理、医院感染控制及指南方法学等多学科专家组成的指南制定小组,根据现有科学证据制定了本临床实践指南,以解答有关CRGNB检测、抗菌治疗及感染预防控制的系列临床优先问题。本指南聚焦于碳青霉烯类耐药肠杆菌目细菌、碳青霉烯类耐药鲍曼不动杆菌和碳青霉烯类耐药铜绿假单胞菌,从当前临床实践的角度提出16个临床问题,采用人群、干预、对照及预后（population, intervention, comparator, outcomes,PICO）格式转换为研究问题,全面收集和综合分析相关研究证据。采用推荐的分级、评估、制定与评价（grading of recommendations, assessment, development and evaluation, GRADE）方法评估相应干预措施的证据体质量、效益及风险,从而制定推荐意见或建议。随机对照临床试验及系统评价获得的结果被优先用于治疗相关临床问题的推荐证据。在缺乏随机对照临床试验的情况下,观察性研究、非对照研究和专家意见被考虑作为补充证据。推荐意见分为强推荐或弱推荐（有条件推荐）。结合中国的临床实践经验,本指南同时提出实施建议,便于指南推荐意见的临床实施。本指南对耐药菌感染诊疗相关的临床医师等多学科专业人员具有参考价值。

Objective To investigate the changing antimicrobial susceptibility profiles of Pseudomonas aeruginosa to various antibiotics in hospitals across China from 2015 to 2021. Methods The P. aeruginosa strains were isolated from 52 hospitals across China. Antimicrobial susceptibility testing was carried out by Kirby-Bauer method and automated systems according to the unified protocol of CHINET program. The results were interpreted according to the Clinical & Laboratory Standards Institute (CLSI) breakpoints. The data were analyzed with WHONET 5.6 software. Results A total of 129 701 strains of P. aeruginosa were collected from 2015 to 2021, accounting for 8.6% of all clinical isolates. The proportion of P. aeruginosa among non-fermentative gram-negative bacilli was only secondary to the proportion of Acinetobacter spp. Majority (91.4% ± 1.0%) of the P. aeruginosa strains were isolated from inpatients and (66.4 ± 2.8)% of the strains were isolated from respiratory tract secretions. P. aeruginosa strains showed decreasing resistance rates to the antimicrobial agents tested during the 7-year period. More than 90% of the P. aeruginosa strains were resistant to amikacin, polymyxins, and ceftazidime-avibactam. About 1.0%-19.8% of the P. aeruginosa strains from outpatient and emergency departments, 0.6%-40.5% of the strains from ICU inpatients, 0.8%-28.8% of the strains from the inpatients in internal medicine wards, and 1.2%-23.3% of the strains from the inpatients in surgery wards were resistant to the antimicrobial agents tested. About 0.8%- 18.8% of the P. aeruginosa strains isolated from children, 1.2%-26.1% of the strains from adult patients, and 1.0%- 28.5% of the strains from the elderly patients were resistant to the antimicrobial agents tested. Overall, 2.5%-24.2%, 0.7%-27.6%, and 0.6%-20.3% of the P. aeruginosa strains isolated from secondary hospitals, tertiary hospitals, and children's hospitals respectively were resistant to the antimicrobial agents tested. The prevalence of carbapenem-resistant P. aeruginosa was 27.1% (35 153/129 701). Conclusions P. aeruginosa is one of the most common clinical isolates of non-fermentative gram-negative bacilli. P. aeruginosa isolates showed downward resistance rates to the antimicrobial agents tested during the 7-year period. Antimicrobial resistance surveillance is an effective way for controlling the emergence and development of antimicrobial resistance. The antimicrobial resistance profile of P. aeruginosa strains varied with specimen type, clinical setting, and patient age. We should strengthen antimicrobial resistance surveillance and improve rational antibiotic use to prevent and control the spread of antibiotic-resistant P. aeruginosa.

Objective To understand the changing resistance rate of Serratia isolates collected across China to commonly used antibiotics. Methods The participating member hospitals of China Antimicrobial Surveillance Network (CHINET) used disk diffusion method or automated susceptibility testing system to conduct antimicrobial susceptibility testing of Serratia isolates according to the unified technical protocol. Results A total of 17 226 strains of Serratia were collected from 53 hospitals across China from January 2015 to December 2021. The number of Serratia isolates increased from 959 in 2015 to 3 588 in 2021. Overall, about 7.3% (1 265/17 226) of the strains were isolated from outpatients and emergency patients and 92.7% (15 961/17 226) of the strains were isolated from inpatients. About half of the strains (57.5% ± 2.5%) were isolated from respiratory samples, followed by blood samples (11.5% ± 1.5%). Over the 7-year period, the resistance rates of Serratia isolates to the antimicrobial agents tested decreased to some extent except ampicillin, cefazolin and nitrofurantoin. The resistance rates to imipenem and meropenem decreased from 8.1% and 8.3% to 5.3% and 5.2%, respectively. The strains isolated from adults in tertiary hospitals showed higher resistance rates to cefoperazone-sulbactam, ceftazidime-avibactam, cefotaxime, imipenem, nitrofurantoin and tigecycline compared to the strains isolated from secondary hospitals. The strains isolated from tertiary hospitals showed lower resistance rates to other antibacterial agents than the strains isolated from secondary hospitals. The Serratia isolates from children showed resistance rates lower than 5% to cefoperazone-sulbactam, piperacillin-tazobactam, amikacin, trimethoprim-sulfamethoxazole and tigecycline. The Serratia isolates from ICUs generally had higher resistance rates than the isolates from other clinical settings. The overall prevalence of carbapenem-resistant Enterobacterales (CRE) was 8.2% in the 7-year period. Conclusions The Serratia isolates showed slightly decreasing resistance rates to most of the antimicrobial agents tested over the 7-year period from 2015 to 2021. It is particularly important to strengthen antimicrobial resistance surveillance and rational use of antibiotics in order to reduce the resistance rates. Proper implementation of hospital infection control measures can effectively reduce the emergence of drug-resistant bacteria.

Objective To summarize the changing distribution and antimicrobial resistance profiles of Enterobacterales strains isolated from children in CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021. Methods Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated systems. Results were analyzed according to CLSI 2021 breakpoints. Results A total of 81 681 strains isolated from children were collected from 2015 to 2021, accounting for 50.1% of gram-negative isolates from children. The most frequently isolated species were Escherichia coli, Klebsiella spp. and Enterobacter spp.. The main source of the isolates was urine and respiratory tract, accounting for 29.3% and 27.7%, respectively. The prevalence of extended-spectrum β-lactamase in E. coli, Klebsiella pneumoniae and Proteus mirabilis was 48.8%-57.6%, 49.3%-66.7%, and 23.1%-33.8%, respectively. The prevalence of carbapenem-resistant Enterobacterales was 5.7%-9.5%, with a decreasing trend over the 7-year period. The prevalence of carbapenem-resistant Klebsiella spp., carbapenem-resistant Enterobacter spp., and carbapenem-resistant E. coli was 14.1%-22.6%, 7.1%-15.7%, and 2.0%-3.4%, respectively. The Enterobacterales showed higher resistance rates to ciprofloxacin compared to levofloxacin. The Enterobacterales strains were still highly susceptible to amikacin, polymyxin B, and tigecycline. More than 70% of the Salmonella spp. strains were resistant to ampicillin, while lower than 30% of these strains were ressitant to ceftriaxone. Conclusions Some Enterobacterales species isolated from children such as E. coli and K. pneumoniae showed decreasing resistance to commonly used antimicrobial agents. However, continuous monitoring of bacterial resistance should be strengthened in order to prevent and control the spread of drug-resistant bacteria.

Objective To know the changing distribution and antimicrobial resistance profiles of Acinetobacter spp. isolated from 51 hospitals across China from 2015 to 2021. Methods According to the CHINET antimicrobial resistance surveillance program, antimicrobial susceptibility testing for isolates was conducted by Kirby-Bauer method and automatic microbiological analysis systems. The susceptibilities of the isolates to antimicrobial agents tested were interpreted according to CLSI 2021 breakpoints. The data were analyzed by WHONET 5.6 software. Results During the period from 2015 to 2021, a total of 143 393 clinical isolates of Acinetobacter were collected, among which Acinetobacter baumannii was the most common species, accounting for 89.6% of all Acinetobacter strains. Overall, 73.0% of the Acinetobacter strains were from respiratory tract. The majority of the Acinetobacter strains were from inpatients (94.0%), of which isolates from ICUs accounted for 35.5%. Acinetobacter strains showed high resistance rates to antimicrobial agents such as β-lactams, aminoglycosides and fluoroquinolones except for minocycline, tigecycline and polymyxin B. The antimicrobial resistance pattern of Acinetobacter strains varied with different levels of hospitals and different departments. During the period from 2015 to 2021, the resistance rate of A. baumannii to cefoperazone-sulbactam and piperacillin-tazobactam had increased, while the resistance rate to minocycline and tigecycline showed a downward trend. The prevalence of carbapenem-resistant A. baumannii was high, reaching 75.2% in tertiary hospitals. Conclusions Acinetobacter spp. is an important pathogen of nosocomial infections, which showed high resistance rates to commonly used antimicrobial agents in clinical practice. Polymyxin B, tigecycline and minocycline are appropriate for treatment of multidrug-resistant Acinetobacter infections.

Objective To investigate the resistance profile of clinical Streptococcus isolates collected from hospitals in several major regions of China during the period from 2015 to 2021. Methods These clinical strains were collected from 51 hospitals. Antimicrobial susceptibility testing was carried out according to a unified protocol of CHINET using Kirby-Bauer method, E-test or automated commercial systems. Results were analyzed according to CLSI M100 2022 breakpoints. Results A total of 89 684 Streptococcus strains were collected from 2015 to 2021, including 35 254 strains (39.3%) of Streptococcus pneumoniae, 42 563 strains (47.6%) of β-hemolytic Streptococcus, and 11 767 strains (13.1%) of Streptococcus viridans. Group A, B, and unclassified Streptococcus accounted for 39.8%, 52.8% and 7.4%, respectively, among the 42 563 strains of β-hemolytic Streptococcus. The prevalence of penicillin-susceptible S. pneumoniae (PSSP), penicillin-intermediate S. pneumoniae (PISP), and penicillin-resistant S. pneumoniae (PRSP) was 86.2%-97.7%, 1.7%-6.5%, and 0.6%-7.3%, respectively, among the 25 552 S. pneumoniae strains isolated from non-cerebrospinal fluid (CSF) specimens in pediatric patients. The prevalence of PSSP, PISP, and PRSP was 92.0%-95.1%, 3.8%-5.3%, and 1.4%-2.7%, respectively, in the 7 997 strains of S. pneumoniae isolated from non-CSF specimens in adult patients. The prevalence of PRSP was 81.2% in the strains isolated from CSF specimens. Regardless of whether S. pneumoniae strains were isolated from CSF or non-CSF specimens, the strains isolated from both pediatric and adult patients were highly resistant to erythromycin and clindamycin, higher than 90% of the strains resistant in nearly all hospitals. β-hemolytic Streptococcus was sensitive to penicillin and ceftriaxone, and no resistant strains were found. The resistance rate of α-hemolytic Streptococcus to penicillin was 5.7% to 8.5%. About 46.3% to 55.0% of group B β-hemolytic Streptococcus isolates were resistant to levofloxacin, while other Streptococcus strains were still highly sensitive to levofloxacin. No strains resistant to linezolid or vancomycin were found in Streptococcus isolates. Conclusions Penicillin remains the first choice for non-central nervous system infections caused by Streptococcus. Streptococcus isolates are still highly resistant to erythromycin and clindamycin.

Objective This study aims to analyze the clinical characteristics, antimicrobial susceptibility, and treatments of Nocardia infections in southwest of China. Methods We conducted a retrospective survey of 33 patients clinically diagnosed with nocardiosis at West China Hospital of Sichuan University from 2010 to 2020. Results The patients included 12 females and 21 males. At least one underlying disease was reported in 28 (84.8%) patients. Immunosuppressive drugs or steroids treatment were used in 13 (39.4%) cases. The common underlying disease included chronic pulmonary disease in 9 cases (27.3%), cardiovascular disease in 8 cases (24.2%), autoimmune disease and renal disease in 7 cases each (21.2%), diabetes mellitus in 6 cases (18.2%) and liver disease in 4 cases (12.1%). The clinical type of nocardiosis included cutaneous (24.2%, 8/33), pulmonary (36.4%, 12/33), neurological (9.1%, 3/33), and disseminated nocardiosis (30.3%, 10/33). All of the Nocardia isolates (100%) were susceptible to amikacin, linezolid and tetracyclines, followed by 90.9% to trimethoprim-sulfamethoxazole (TMP-SMX), 75.0% to gentamycin, 73.7% to third or fourth generation cephalosporins, 70.0% to carbapenems, 46.7% to fluoroquinolones, and 14.3% to penicillins. Twenty-six (78.8%) patients received TMP-SMZ either as monotherapy, or in combination with carbapenems, linezolid, amikacin, or third generation cephalosporins. Twenty-seven (81.8%) patients were clinically improved after antimicrobial treatment. Treatment failed in 6 cases (18.2%). The patients were transferred to local hospital or left hospital voluntarily after treatment failure.The patients with central nervous system (CNS) nocardiosis showed evidently worse outcome than those without CNS involvement (P = 0.005).Conclusions Nocardia infection should be considered particularly in immunocompromised patients. TMP-SMX alone or in combination is still the cornerstone for treatment of nocardiosis. Nocardiosis involving CNS usually predicts worse prognosis.

Objective To investigate the susceptibility and resistance of clinical isolates collected from hospitals in several regions of China. Methods These clinical strains were collected from 51 hospitals. Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated systems. Results were analyzed according to CLSI 2021 breakpoints. Results A total of 301 917 clinical isolates were collected from January to December 2021, of which gram negative organisms and gram positive cocci accounted for 71.4% and 28.6% respectively. Methicillin-resistant strains in S. aureus (MRSA), S. epidermidis and other Staphylococcus species (except S. pseudintermedius and S. schleiferi) accounted for 30.0%, 80.7% and 77.7% respectively. MR strains showed much higher resistance rates to most of other antimicrobial agents than MS strains. However, 92.4% of MRSA strains were still susceptible to trimethoprim-sulfamethoxazole, while 90.7% of MRSE strains were susceptible to rifampin. No staphylococcal strains were found resistant to vancomycin. E. faecalis strains demonstrated much lower resistance rates to most of the drugs tested than E. faecium. A few strains of both Enterococcus species were resistant to vancomycin. The prevalence of PSSP was 97.8% in the non-meningitis S. pneumoniae isolates from children and 95.1% in the non-meningitis S. pneumoniae isolates from adults. The Enterobacterales strains were still highly susceptible to carbapenems. Overall, less than 13% of these strains were resistant to carbapenems. K. pneumoniae isolates showed increasing resistance rates to imipenem and meropenem, from 3.0% and 2.9% in 2005 to 25.0% and 26.3% in 2018. However, the resistance rates of Klebsiella pneumoniae to imipenem and meropenem decreased since 2019. About 65.6% and 66.5% of Acinetobacter spp. were resistant to imipenem and meropenem, respectively. Overall, 23.0% and 18.9% of the Pseudomonas aeruginosa isolates were resistant to imipenem and meropenem, respectively. Conclusions Bacterial resistance to commonly used antibiotics is still on the rise. However, the prevalence of carbapenem-resistant K. pneumoniae and P. aeruginosa is decreasing in recent years. It is suggested that strengthening the monitoring of bacterial resistance and multidisciplinary teamwork are effective in controlling the spread of drug-resistant bacteria.

Objective To investigate the susceptibility and resistance pattern of clinical isolates in hospitals across China. Methods These clinical strains were collected from 52 hospitals. Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated systems. Results were analyzed according to CLSI 2020 breakpoints. Results A total of 251 135 clinical isolates were collected from January to December 2020, of which gram negative organisms and gram positive cocci accounted for 71.9% and 28.1%, respectively. Methicillin-resistant strains in S. aureus (MRSA), S epidermidis and other Staphylococcus spp. (except S. pseudintermedius and S. schleiferi) accounted for 31.0%, 81.7%, and 77.5%, respectively. The resistance rates of MR strains to most of other antimicrobial agents were much higher than those of MS strains. However, 93.6% of MRSA strains were still susceptible to trimethoprim-sulfamethoxazole, while 89.9% of MRCNS strains were susceptible to rifampin. No staphylococcal strains were found resistant to vancomycin. E. faecalis strains showed much lower resistance rates to most of the drugs tested than E. faecium. A few strains of both species were resistant to vancomycin. Among the S. pneumoniae strains isolated from children and adults, the prevalence of PSSP (96.7% and 95.5%, respectively) strains were higher than those isolated in 2019. The prevalence of PISP and PRSP were lower than those isolated in 2019. The strains of Enterobacteriaceae were still highly susceptible to carbapenems, Overall, less than 12% of these strains (except Klebsiella) were resistant to carbapenems. The percentage of K. pneumoniae strains resistant to imipenem and meropenem increased from 3.0% to 25.0% and from 2.9% to 26.3%, respectively from 2005 to 2018. However, the prevalence of imipenem- and meropenem-resistant Klebsiella strains decreased in 2019 and 2020. About 68.1% and 69.0% of Acinetobacter spp. strains were resistant to imipenem and meropenem, respectively. The resistance rates of Pseudomonas aeruginosa to imipenem and meropenem were 23.2% and 19.3%, respectively. Conclusions The prevalence of carbapenem-resistant K. pneumoniae and P. aeruginosa decreased even though bacterial resistance to commonly used antibiotics is still on the rise. It is necessary to strengthen the surveillance of bacterial resistance and the measures for control of infectious diseases.

Objective To investigate the clinical characteristics and risk factors for death of candidemia for better prevention and reasonable diagnosis and treatment of candidiasis. Methods The clinical and microbiological data of patients diagnosed with candidemia in a hospital from January 2015 to December 2019 were retrospectively analyzed. The patients were assigned to survivor group and death group according to the outcome of the patients. Univariate analysis and binary logistic regression analysis were conducted to identify the risk factors for death. Results A total of 97 patients were diagnosed with candidemia in the 5-year period. Overall, 99 strains of Candida were isolated from blood, of which Candida albicans, Candida parapsilosis, Candida glabrata, and Candida tropicalis accounted for 32.3%, 25.3%, 22.2% and 20.2%, respectively. The candidemia cases were mainly found in the department of gastroenterology (26.3%), cardiovascular surgery (23.2%), and burn and skin surgery (17.2%). The 4 Candida species showed significantly different susceptibility rates to triazole drugs (P < 0.05). Non-albicans Candida strains demonstrated higher resistance rates than C. albicans. Thirty (30.9%) of the 97 patients died. Univariate analysis showed that ICU admission, different departments, indwelling urinary catheter, chest drainage tube, and cardiovascular implant, suffered from hypertension, (1,3)-β-D-glucan > 100 ng/L were associated with mortality (P < 0.05). Binary logistic analysis indicated that ICU admission (OR=4.942, 95% CI: 1.574-15.515, P = 0.006) and indwelling pleural drainage tube (OR=5.678, 95% CI: 1.427-22.598, P = 0.014) were independent risk factors for death in patients with candidemia. Conclusions Non-albicans Candida species are the main pathogens of candidemia. ICU admission and indwelling chest drainage tube are independent risk factors for the death of patients with candidemia.