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 the omadacycline-based therapies in patients with community-acquired pneumonia (CAP). Methods The clinical data of CAP patients treated with omadacycline (± β-lactam/β-lactamase inhibitor) in the First Affiliated Hospital of Nanchang University from January to May 2023 were reviewed and analyzed. The patients were assigned to omadacycline alone or omadacycline plus β-lactam/β-lactamase inhibitor treatment group. The clinical efficacy, microbiological efficacy, and drug-related adverse events were summarized and compared between groups. Results A total of 135 adult patients with CAP were enrolled, including 23 (17.04%) patients with chronic liver disease, 25 (18.52%) patients with chronic kidney disease, and 64 (47.41%) patients treated with omadacycline alone. The overall clinical efficacy rate was 81.48% (110/135), specifically 79.69% (51/64) in the patients treated with omadacycline alone and 83.10% (59/71) in the patients treated with omadacycline plus β-lactam/β-lactamase inhibitor. The clinical efficacy rate was 86.36% (38/44) in the patients treated in the general ward. Overall, 21 cases of drug-related adverse events (mainly nausea) were reported in 15 patients, all of which were mild to moderate. Conclusions Omadacycline has shown good therapeutic effect in treatment of CAP in Chinese adults, especially for the patients treated in general ward. Most of the adverse events of omadacycline were mild to moderate and tolerable.

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 A total of 289 760 nonduplicate clinical strains of E. 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 among β-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 antimicrobial susceptibility, resistance mechanisms, and molecular characteristics of clinical isolates of carbapenem-resistant Enterobacterales (CRE) (except Klebsiella pneumoniae) in China. Methods The CRE strains (except K. pneumoniae) were isolated from 151 medical institutions in 31 provinces, municipalities and autonomous regions of China from January to June 2021 and tested in 3 central laboratories. The antimicrobial susceptibility of CRE was determined by broth microdilution method. Whole genome sequencing was performed to analyze the carbapenemase genes and multilocus sequence typing (MLST) of all strains. Results A total of 946 CRE strains were collected, among which Escherichia coli, Enterobacter cloacae and other Enterobacterales accounted for 41.1% (389/946), 34.4% (325/946) and 24.5% (232/946), respectively. Antimicrobial susceptibility testing showed that E. coli, E. cloacae and other Enterobacterales were highly sensitive to aztreonam-avibactam, amikacin, colistin, polymyxin B and tigecycline, and 87.1%-95.5% of the strains were susceptible to these drugs. Whole genome sequencing indicated that bla_NDM-5 (71.7%, 279/389) and bla_NDM-1 (64.3%, 209/325) were the predominant carbapenemase gene types in E. coli and E. cloacae, respectively, while bla_NDM-1 was predominant in C. freundii and K. aerogenes strains, accounting for 73.8% (31/42) and 57.8% (37/64), respectively. Among K. oxytogenes, bla_KPC-2 and bla_NDM-1 accounted for 30.4% (14/46) and 26.1% (12/46), respectively. A total of 87 ST types of E. coli were identified, mainly ST410 (22.1%, 86/389) and ST167 (10.5%, 41/389). ST410 E. coli was mainly isolated in Fujian, Hebei, Hunan, Inner Mongolia and Yunnan provinces, and ST167 E. coli was mainly isolated in Beijing, Hainan, Henan, Liaoning and Qinghai provinces. There were 54 ST types of E. cloacae, mainly ST171 (17.8%, 58/325) and ST78 (7.1%, 23/325). ST171 E. cloacae was mainly found in Anhui, Hebei, Heilongjiang and Henan provinces, while ST78 E. cloacae was mainly found in Hubei, Guangxi and Guizhou provinces. Conclusions Carbapenemase production is the main mechanism underlying carbapenem resistance of Enterobacterales in China. The clonotypes of CRE strains varied with geographic regions of China.

Objective To investigate the changing antimicrobial resistance profiles of Streptococcus pneumoniae isolates from children in Chongqing area from 2011 to 2022, and to provide evidence for rational use of antibiotics and prevention of nosocomial infections. Methods The clinical data of S. pneumoniae strains isolated from pediatric patients during 2011-2022 were retrospectively analyzed. Antimicrobial susceptibility testing was performed with commercial automated systems and E-test. The results were interpreted according to the breakpoints in CLSI document (2022 edition). Results A total of 26 668 strains of S. pneumoniae were isolated during the 12-year period. The proportion of S. pneumoniae was 16.0% in the total pathogenic bacterial isolates and 46.4% in all the gram-positive bacterial pathogens. S. pneumoniae strains were mainly isolated from respiratory specimens (97.1%), followed by blood samples (1.5%). The highest proportion of S. pneumoniae isolates was in infants (38.2%), followed by toddlers (32.4%), preschool age (22.9%), school age (5.6%), adolescents (0.6%) and neonates (0.4%). All of the 38 strains of nonmeningitis S. pneumoniae (0.1%) isolated from cerebrospinal fluid were resistant to penicillin. Overall, 35.7% and 32.4% of these strains were resistant to cefotaxime and meropenem, respectively. The majority of S. pneumoniae (99.9%, 26 630/26 668) were nonmeningitis isolates. The prevalence of penicillin-susceptible (PSSP), -intermediate (PISP), and-resistant (PRSP) strains was 71.9% (16 083), 25.1% (5 610), and 3.0% (674), respectively. The prevalence of PRSP in infants and preschool children was higher than that in other age groups. The nonmeningitis S. pneumoniae isolates showed higher than 95% resistance rate to erythromycin, clindamycin and tetracycline, but 0.2%, 0.2% and 0.1% resistance rate to levofloxacin, moxifloxacin and rifampicin, respectively. No S. pneumoniae strains were found resistant to vancomycin or linezolid. Conclusions The proportion and antimicrobial resistance profiles of S. pneumoniae strains isolated from pediatric patients varied with age group and specimen type. The decreasing prevalence of PRSP may inform empirical treatment of S. pneumoniae infections in children in Chongqing area.

Objective To analyze the general condition, etiological characteristics, antibiotic use, treatment and prognosis of adult patients with pyogenic liver abscess (PLA) in order to improve the diagnosis and treatment of PLA. Methods The clinical data of adult patients diagnosed with PLA who were hospitalized in Tianjin Medical University General Hospital from December 2019 to December 2022 were retrospectively analyzed, including general information, pathogen culture and antimicrobial susceptibility testing results, treatment and outcomes. The etiological characteristics and the use of clinical anti-infective drugs were analyzed. Results A total of 280 adult patients with PLA were enrolled, including 161 males and 119 females (male/female ratio: 1.35:1). The average age was 63.1 ± 13.6 years. PLA was most frequently found in the patients of 50-80 years of age. The most common route of infection was cryptogenic infection (55.7%). The most common underlying disease was diabetes mellitus (41.1%). The positive rate of bacterial culture was 28.4% from blood, and 80.3% from pus. Klebsiella pneumoniae and Escherichia coli were the most common bacteria isolated from blood culture and pus culture. A total of 14 strains of antibiotic-resistant bacteria were identified, including 3 strains of extended-spectrum β-lactamase (ESBLs)-producing K. pneumoniae, 3 strains of ESBLs-producing E. coli, 1 strain of carbapenem-resistant K. pneumoniae, and 1 strain of carbapenem-resistant E. coli. There were 2 strains of methicillin-resistant Staphylococcus, 3 strains of high level ampicillin and aminoglycoside resistant Enterococcus, and 1 strain of vancomycin-resistant Enterococcus. The gram-negative pathogens showed the lowest susceptibility rate to levofloxacin (82.3%) and the highest susceptibility rate to imipenem (98.2%). Overall, the gram-negative pathogens were generally susceptible to cephalosporins/β-lactamase inhibitor combinations, penicillins/β-lactamase inhibitor combinations, aminoglycosides, glycylcyclines, cephamycins, carbapenems and sulfonamides. Cephalosporins/β-lactamase inhibitor combinations are the most commonly used initial empirical treatment for PLA. Conclusions PLA is more common in men, especially the patients of 50-80 years of age and those complicated with diabetes mellitus. K pneumoniae was the major pathogen, which was sensitive to most commonly used antibiotics. The empirical treatment is mainly cephalosporins/β-lactamase inhibitor combinations. Carbapenems were also used frequently. Attention should be paid to unnecessary combination therapies and irrational use of antibiotics.

Objective To report two cases of meningitis caused by Corynebacterium and review relevant literature to enhance clinical awareness of the pathogenicity of Corynebacterium species. Methods The clinical details were reported for 2 cases of meningitis caused by Corynebacterium. Similar case reports were retrieved from PubMed, CNKI, Wanfang, VIP, and CBM databases using search terms “Corynebacterium meningitis” and “cerebrospinal fluid shunt infection”. Clinical data of the identified patients were reviewed and analyzed. Results Both patients with meningitis caused by Corynebacterium developed symptoms of fever, abdominal pain, and unconsciousness following lumboperitoneal shunt procedures. The culture of cerebrospinal fluid was positive for Corynebacterium. Both patients improved significantly after vancomycin treatment. Literature search yielded 29 similar cases. Overall, the 31 cases (including the two cases in this report) included 20 males and 11 females, aged between 4 weeks to 87 years. The identified Corynebacterium species included C. jeikeium in 12 cases, C. striatum in 9 cases, C. xerosis in 2 cases, C. bovis in 2 cases, C. aquaticum, C. equine, and C. minutissimum one case each, and unspecified Corynebacterium species in 3 cases. Underlying diseases were reporetd in most patients, including immune disorder in 2 cases, malignant tumor in 8 cases, genetic disease in 2 cases, premature with hydrocephalus in 4 cases, brain trauma in 2 cases, intracranial vascular malformation in 2 cases, and cerebral aneurysm in 2 cases. Risk factors for Corynebacterium meningitis included chemotherapy for malignancy in 5 cases, long term use of steroids and immunosuppressants in 2 cases, invasive procedures in 24 cases, and prior antibiotic use in 11 cases. Vancomycin was the most commonly prescribed treatment. The drainage tube and/or venous catheter were also removed or replaced in 19 cases. Twenty-five patients recovered after treatment and 6 patients died. Conclusions Corynebacterium species are emerging as opportunistic pathogens. Clinicians should be aware of the infections caused by Corynebacterium if patients have undergone invasive procedures or are immunocompromised, especially when associated with fever, altered consciousness, and clinical signs of encephalitis/meningitis. If cerebrospinal fluid test is positive for Corynebacterium, specific treatment should be prescribed promptly for Corynebacterium infection.

Objective To investigate the changing distribution and antibiotic resistance profiles of clinical isolates of Staphylococcus in hospitals across China from 2015 to 2021. Methods Antimicrobial susceptibility testing was conducted for the clinical isolates of Staphylococcus according to the unified protocol of CHINET (China Antimicrobial Surveillance Network) using disk diffusion method and commercial automated systems. The CHINET antimicrobial resistance surveillance data from 2015 to 2021 were interpreted according to the 2021 CLSI breakpoints and analyzed using WHONET 5.6. Results During the period from 2015 to 2021, a total of 204,771 nonduplicate strains of Staphylococcus were isolated, including 136,731 (66.8%) strains of Staphylococcus aureus and 68,040 (33.2%) strains of coagulase-negative Staphylococcus (CNS). The proportions of S. aureus isolates and CNS isolates did not show significant change. S. aureus strains were mainly isolated from respiratory specimens (38.9 ± 5.1)%, wound, pus and secretions (33.6 ± 4.2)%, and blood (11.9 ± 1.5)%. The CNS strains were predominantly isolated from blood (73.6 ± 4.2)%, cerebrospinal fluid (12.1 ± 2.5)%, and pleural effusion and ascites (8.4 ± 2.1)%. S. aureus strains were mainly isolated from the patients in ICU (17.0 ± 7.3)%, outpatient and emergency (11.6 ± 1.7)%, and department of surgery (11.2±0.9)%, whereas CNS strains were primarily isolated from the patients in ICU (32.2 ± 9.7)%, outpatient and emergency (12.8 ± 4.7)%, and department of internal medicine (11.2 ± 1.9)%. The prevalence of methicillin-resistant strains was 32.9% in S. aureus (MRSA) and 74.1% in CNS (MRCNS). Over the 7-year period, the prevalence of MRSA decreased from 42.1% to 29.2%, and the prevalence of MRCNS decreased from 82.1% to 68.2%. MRSA showed higher resistance rates to all the antimicrobial agents tested except trimethoprim-sulfamethoxazole than methicillin-susceptible S. aureus (MSSA). Over the 7-year period, MRSA strains showed decreasing resistance rates to gentamicin, rifampicin, and levofloxacin, MRCNS showed decreasing resistance rates to gentamicin, erythromycin, rifampicin, and trimethoprim-sulfamethoxazole, but increasing resistance rate to levofloxacin. No vancomycin-resistant strains were detected. The prevalence of linezolid-resistant MRCNS increased from 0.2% to 2.3% over the 7-year period. Conclusions Staphylococcus remains the major pathogen among gram-positive bacteria. MRSA and MRCNS were still the principal antibiotic-resistant gram-positive bacteria. No S. aureus isolates were found resistant to vancomycin or linezolid, but linezolid-resistant strains have been detected in MRCNS isolates, which is an issue of concern.

Objective To investigate the distribution and antimicrobial resistance of clinical isolates in the First Affiliated Hospital of Xi'an Jiaotong University in 2022 for rational use of antibiotics in clinical practice. Methods Nonduplicate clinical isolates were collected from January 1, 2022 to December 31, 2022. Antimicrobial susceptibility testing was carried out using Kirby-Bauer method and automated systems. The data were analyzed using WHONET 5.6 software and interpreted according to the Clinical and Laboratory Standards Institute (CLSI) breakpoints (2021 Edition). Results Of the 8 638 clinical isolates, gram negative bacteria and gram positive bacteria accounted for 60.8% (5 253/8 638) and 39.2% (3 385/8 638), respectively. The prevalence of methicillin-resistant strains was 33.0% in S. aureus (MRSA), 75.8% in S. epidermidis (MRSE), and 51.9% in other coagulase-negative Staphylococcus (MRCNS). No staphylococcal strains were found resistant to vancomycin. The prevalence of vancomycin-resistant E. faecium was 0.6%, and no vancomycin-resistant E. faecalis was found. E. faecalis strains showed higher resistance rate to linezolid (5.2%) than E. faecium (0.7%). The prevalence of carbapenem-resistant Enterobacterales (CRE) was 7.9%, specifically 12.1% for carbapenem-resistant K. pneumoniae (CRKP) and 1.6% for carbapenem-resistant E. coli (CREC). The prevalence of carbapenem-resistant P. aeruginosa (CRPA) and carbapenem-resistant A. baumannii (CRAB) was 30.9% and 77.0%, respectively. Conclusions Clinical microbiology laboratories should strengthen the collection and testing of clinical specimens from the sites of infection in order to improve pathogenic diagnosis and antimicrobial resistance surveillance. This is conducive to the rational use of antibiotics and reduce the further spread of multidrug-resistant bacteria.

Objective To investigate the relationship between the levels of CD4⁺/CD8⁺ and D-dimer (D-D) in peripheral blood and the outcome of Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH). Methods Ninety patients with EBV-HLH who were treated in Beijing Friendship Hospital from September 2021 to August 2023 were included as observation group, and additional 90 patients with infectious mononucleosis (IM) treated in the hospital contemporarily were selected as the control group. The levels of CD4⁺/CD8⁺ and D-D in peripheral blood were compared between the two groups of patients to examine the correlation between the levels of CD4⁺/CD8⁺ and D-D in peripheral blood and EBV-DNA load in patients with EBV-HLH, compare the outcome of patients within 3 months in terms of the levels of CD4⁺/CD8⁺ and D-D in peripheral blood, evaluate the effects of CD4⁺/CD8⁺ and D-D levels in peripheral blood on the risk of death from EBV-HLH, and analyze the interaction between the levels of CD4⁺/CD8⁺ and D-D in peripheral blood. Results The patients in observation group showed significantly lower peripheral blood CD4⁺/CD8⁺ ratio and significantly higher D-D than the patients in control group (P < 0.05). The peripheral blood CD4⁺/CD8⁺ ratio was negatively correlated with EBV-DNA load (P < 0.05), and D-D was positively correlated with EBV-DNA load (P < 0.05) in EBV-HLH patients. The patients with high peripheral blood CD4⁺/CD8⁺ ratio were assocaited with lower 3-month mortality rate compared to the patients with low CD4⁺/CD8⁺ ratio. The patients with high D-D level were associated with higher 3-month mortality rate compared to the patients with low D-D level (P < 0.05). In EBV-HLH patients with low levels of peripheral blood CD4⁺/CD8⁺, the risk of death was 6.125 times that of the patients with high levels of CD4⁺/CD8⁺. High level D-D was associated with 14.348 times risk of death compared to the patients with low level D-D. CD4⁺/CD8⁺ and D-D had synergistic effect on death of EBV-HLH patients. Conclusions Peripheral blood CD4⁺/CD8⁺ levels decreased and D-D levels increased in EBV-HLH patients. Peripheral blood CD4⁺/CD8⁺ levels and D-D levels and their changes may be useful for predicting the outcome of patients.

Objective To summarize the clinical characteristics of delayed diagnosis of tuberculosis in children, analyze the risk factors of delayed diagnosis, and support early diagnosis of tuberculosis in children. Methods This is a retrospective analysis based on the clinical data of tuberculosis patients admitted to the Children's Hospital Affiliated to Zhengzhou University from January 2015 to February 2023. The clinical characteristics of children were analyzed in terms of age group. According to the definition of diagnosis delay, the patients were assigned to delayed group and non-delayed group. Univariate analysis and multivariate logistic regression were used to analyze the risk factors for diagnosis delay. Results A total of 82 children with tuberculosis were included (46 cases in delayed diagnosis group and 36 cases in non-delayed diagnosis group). The rate of diagnosis delay was 56.1%. The incidence of acute miliary pulmonary tuberculosis and tuberculous meningitis was significantly higher in children ≤5 years old than that in children > 5 years old (P < 0.05). Diagnosis delay was associated with significantly higher prevalence of chronic fever, cough > 2 weeks, growth retardation and significantly longer duration of empirical antibiotic use compared to the children without diagnosis delay (P < 0.05). Univariate analysis showed that patient origin, contact history, mixed infection, tuberculosis type, molecular biological assay and severe disease were related to the delay of TB diagnosis (P < 0.05). Multivariate logistic regression analysis showed that patient origin [≥3 clinic visits (OR = 7.064, 95% CI: 1.677-29.754)], mixed infection (OR = 3.812, 95% CI: 1.185-12.260), severe disease (OR = 3.697, 95% CI: 1.081-12.646)] were risk factors for diagnosis delay in children. Molecular biological assay (OR = 4.642, 95% CI: 1.318-16.345) was a protective factor. Conclusions The clinical symptoms of tuberculosis in children are atypical. Delayed diagnosis of tuberculosis is common. Multiple clinic visits, mixed infection, and severe disease are the risk factors for diagnosis delay. Tuberculosis should be taken into account for the children with chronic fever, cough and growth retardation who have failed to respond to adequate therapy with third-generation cephalosporin and carbapenems. Molecular biological assay is helpful for early diagnosis of tuberculosis in children with negative sputum smear.

Objective To investigate the distribution and antimicrobial resistance of bacterial isolates from blood samples in the hospitals participating in China Antimicrobial Surveillance Network (CHINET) from 2015 to 2021. Methods Bacterial strains isolated from blood samples were collected from 52 medical centers participating in CHINET from 2015 to 2021 for analysis of bacetrial distribution and antimicrobial resistance. Results A total of 153 591 isolates were collected, 48.8% of which were gram-positive bacteria and 51.2% were gram-negative bacteria. The top five bacterial strains were coagulase negative Staphylococcus (28.2%), Escherichia coli (20.7%), Klebsiella (13.7%), Enterococcus (7.2%), and Staphylococcus aureus (6.6%). Compard to female patients, male patients showed lower proportion of E. coli and higher proportions of other bacterial species in all the bacterial isolaets from blood samples. The proportions of Streptococcus pneumoniae and Salmonella in all the bacterial isolaets from blood samples were higher in children compared to adults. Enterobacterales species showed various resistance rates to antimicrobial agents. Overall, ≥58.0%, ≥36.8% and ≥56.8% of E. coli strains were resistant to cefotaxime, gentamicin and levofloxacin respectively over the 7-year period. However, less than 2.5% of the E. coli strains were resistant to carbapenems. K. pneumoniae showed higher resistance rates to imipenem and meropenem than other Enterobacterales species. During the 7-year period, the prevalence of imipenem-resistant and meropenem-resistant K. pneumoniae increased from 21.4% and 19.9% in 2015 to 25.7% and 26.6% in 2021, respectively. However, carbapenems still maintained good antibacterial activity against other Enterobacterales, associaetd with lower resistance rates. In the 7-year period, Acinetobacter baumannii showed a dwonward trend in the resistance rates to imipenem and meropenem, but remained 72.9% and 73.2% respectively in 2021. The prevalence of imipenem-resistant and meropenem-resistantP. aeruginosa decreased from 26.7% and 22.9% in 2015 to 18.5% and 14.7% in 2021, respectively. The prevalence of PRSP was 1.5% in the isolaets from adults and and 0.8% in the isolates from children. Less than 3.0% of the Enterococcus faecium and Enterococcus faecalis strains were resistant to vancomycin, teicolanin, or linezolid. The prevalence of methicillin-resistant S. aureus (MRSA) and coagulase negative Staphylococcus (MRCNS) was 32.1% and 81.0%, respectively. The prevalence of MRSA was relatively stable, 28.5% in 2015 and 28.0% in 2021. Conclusions Coagulase negative Staphylococcus, E. coli and K. pneumoniae were the main bacterial species isolated from blood samples in the hospitals participaing in the CHINET from 2015 to 2021. Significant sex and age differences were found in the distribution of bcterial isolates from blood samples. The overall resistance rates of the top bacetrial strains from blood samples to antimicrobial agents showed a downward trend. Ongoing surveillance of antimicrobial resistance for the isolates from blood samples is still essential for prescribing rational antimicrobial therapies and curbing bacterial resistance.

Objective To investigate the correlation between baseline plasma soluble triggering receptor expressed on myeloid cell-1 (sTREM-1), steroid hormone cortisol and dehydroepiandrosterone (DHEA), immunoendocrine markers, and disease severity in patients with pulmonary tuberculosis (PTB). Methods From March 2020 to May 2022, 76 PTB patients and 78 healthy controls were recruited. The plasma sTREM-1 levels were compared between controls and PTB patients. Plasma sTREM-1 and C-reactive protein (CRP), interleukin (IL)-6 and interferon (IFN)-γ, erythrocyte sedimentation rate (ESR), steroid hormone cortisol and dehydroepiandrosterone (DHEA) were analyzed to correlate with inflammatory transcripts (IL-6, IFN-γ) in peripheral blood mononuclear cells. Results The sTREM, CRP, ESR, IL-6, IFN-γ, cortisol and cortisol/DHEA were significantly increased (P < 0.05) while DHEA was significantly decreased (P < 0.05) in PTB patients compared with the control group. Futhermore, severe PTB patients had higher sTREM-1 and ESR levels than mild and moderate PTB patients. Spearman correlation analysis showed that sTREM-1 was significantly positively correlated with CRP in all patients (P < 0.05). Only in patients with severe PTB, sTREM-1 was significantly positively correlated with cortisol/DHEA (P < 0.05), and significantly negatively correlated with DHEA (P < 0.05). Conclusions High plasma sTREM-1 levels may be an important factor contributing to the persistence of immunoendocrine imbalance specific to advanced disease in patients with PTB.

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 clinical distribution, antimicrobial resistance, carbapenemase resistance genes, virulence genes, capsular serotypes and ST subtypes of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains in intensive care unit of a tertiary hospital in Hunan Province for better management of CRKP infections. Methods CRKP strains were isolated from 8 intensive care units of the First People’s Hospital of Chenzhou City from January 2020 to December 2021. The isolates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and tested by VITEK Compact 2 for antimicrobial susceptibility. Carbapenemase phenotype was detected by modified carbapenem inactivation method (mCIM). The capsular serotypes were determined by wzi sequencing. Carbapenem resistance genes and virulence genes were identified by PCR and Sanger sequencing. The strains were also analyzed by multilocus sequence typing (MLST) in terms of ST subtypes. Results The 75 CRKP strains were mainly isolated from geriatric ICU (28.0%) and neurosurgery ICU (20.0%). Overall, 6.7% (5/75) and 16.0% (12/75) of the CRKP strains were resistant to tigecycline and ceftazidime-avibactam, respectively. The CRKP strains (>96.0% resistant) were highly resistant to carbapenems, cephalosporins, β-lactam/β-lactamase inhibitor combinations, and levofloxacin. PCR and sequencing analysis found bla_KPC-2 gene in 61 strains (81.3%), bla_NDM-1 gene in 11 strains (14.7%), bla_NDM-5 gene in 1 strain (1.3%), and bla_OXA-48 gene in 2 strains (2.7%). MLST revealed that ST11 (54.7%, 41/75), ST1883 (13.3%, 10/75), and ST307 (6.7%, 5/75) were the top three ST subtypes. All ST11 and ST1883 CRKP strains harbored bla_KPC-2. KL64 (38.7%, 29/75) and KL47 (25.3%, 19/75) were the most prevalent capsular serotypes among the 75 CRKP strains. The most common virulence genes among these CRKP strains were rmpA2 (48.0%, 36/75), iroN (38.7%, 23/75) and iucA (37.3%, 15/75). Conclusions The CRKP strains isolated from the intensive care units were mainly ST11-KL64 and ST11-KL47 types. Most of the strains harbor bla_KPC-2 and virulence gene, and associated with high level antimicrobial resistance. It is urgent to strengthen the monitoring of molecular epidemiological characteristics of CRKP in order to inform individualized and precision treatment of CRKP infections.

Objective To compare the safety and efficacy of vancomycin in obese patients guided by trough concentration and AUC_24h/MIC, and to provide data for individualized administration of vancomycin in obese patients. Methods We retrospectively collected the data of obese adult patients (BMI ≥ 30 kg/m²) who had severe infection caused by gram-positive cocci and treated with vancomycin intravenously in two Grade A tertiary hospitals in Shanghai from 2012 to 2024. The patients were assigned to trough concentration monitoring group or AUC_24h/MIC monitoring group according to the therapeutic drug monitoring (TDM) method at the time of admission. Nephrotoxicity and efficacy were compared between the two groups of patients. Results A total of 22 obese patients were included in this study, including 12 in the trough concentration monitoring group and 10 in the AUC_24h/MIC monitoring group. No significant difference was found between the two groups in gender, age, BMI, creatinine clearance before treatment, underlying disease, site of infection, pathogen type, or concomitant medications. The proportion of ICU admission was higher in AUC_24h/MIC monitoring group. The length of ICU stay, vancomycin treatment duration, bacterial clearance rate and comprehensive efficacy rate did not show significant difference between the two groups. The average daily dose of vancomycin in trough concentration monitoring group was significantly lower than that in AUC_24h/MIC monitoring group [(1.63 ± 0.59) g vs (2.29 ± 0.72) g, P = 0.026]. The average treatment duration was not significantly different between the two groups [(15.33 ± 10.28) d vs (14.90 ± 6.92) d, P = 0.911]. Compared with the trough concentration monitoring group, the initial peak concentration [(30.99 ± 16.22) mg/L vs (19.41 ± 5.42) mg/L, P = 0.025] and overall peak concentration [(33.67 ± 16.53) mg/L vs (22.08±3.96) mg/L, P = 0.045] of vancomycin were lower in the AUC_24h/MIC monitoring group, but the initial trough concentration [(11.03 ± 8.66) mg/L vs (6.33 ± 4.45) mg/L, P = 0.139] and overall trough concentration [(13.75 ± 9.74) mg/L vs (9.74 ± 4.24) mg/L, P = 0.218] were similar in the two groups. Vancomycin-associated nephrotoxicity did not occur in any group, but 41.7% of the patients in the trough concentration monitoring group reached the threshold of renal toxicity, i.e. trough concentration ≥15 mg/L. Conclusions Vancomycin treatment with conventional dosing regimen still have good clinical efficacy in obese adult patients. Vancomycin therapy guided by AUC_24h/MIC can achieve the target value at lower concentration or exposure, which is promising for reducing vancomycin-associated nephrotoxicity.

Objective To examine the diagnosis and treatment of disseminated infection caused by Enterocytozoon bieneusi in a child with leukemia and improve the awareness of the pathogen in clinical and laboratory practice. Methods A case of disseminated infection caused by Enterocytozoon bieneusi in a child with leukemia in Shanghai Children’s Hospital was retrospectively analyzed, including diagnosis and treatment details. Similar cases were identified from PubMed, Wanfang Data, VIP, and CNKI databases since database establishment until June 30, 2024, using search terms “Enterocytozoon bieneusi”. The relevant literature was reviewed. Results This child had acute lymphoblastic leukemia as the underlying disease and was admitted to hospital for antimicrobial treatment due to fever and abdominal discomfort. The case was considered bacterial infection complicated with Enterocytozoon bieneusi infection, confirmed by detection of Klebsiella pneumoniae in blood and detection of Enterocytozoon bieneusi in blood and ascites by metagenomic next-generation sequencing (mNGS). The treatment was switched to tigecycline plus trimethoprim-sulfamethoxazole at a sufficient dose, which resulted in resolution of symptoms. Six months later, the patient suffered from acute lymphoblastic leukemia and bone marrow depression, Enterocytozoon bieneusi disseminated infection, septic shock. Her family gave up treatment and the child died. Literature review indicated that most patients infected with Enterocytozoon bieneusi had underlying conditions such as organ transplantation, AIDS, and leukemia associated with poor immunity. The onset symptoms are diarrhea, abdominal discomfort, and fever. Enterocytozoon bieneusi was detected by using methods such as modified Masson's trichrome stain, fluorescent calcofluor white staining, molecular detection techniques, and immunofluorescence. The patients were treated with drugs such as albendazole, nitazoxanide, fumagillin, and trimethoprim-sulfamethoxazole. Conclusions Enterocytozoon bieneusi is an opportunistic pathogenic fungus that infects immunocompromised patients and can cause abdominal discomfort, diarrhea, fever, and even disseminated infection and death. Conventional laboratory methods cannot culture Enterocytozoon bieneusi. Molecular detection techniques can be used to identify the pathogen early.

Objective To analyze the relationship between clinical drug utilization and the risk of nosocomial infections among hospitalized patients, and provide evidence for the prevention and control of nosocomial infections. Methods This study adopted a retrospective case-control design. The case group included 209 patients with nosocomial infection reported from January 2023 to December 2023 in a tertiary hospital. The control group included 209 patients without nosocomial infection during the same period. The patients in the control group were selected by stratified sampling based on Charlson Comorbidity Index (CCI). Results Univariate analysis showed that proton pump inhibitors, antacids, immunosuppressants and prior antimicrobial combination therapy increased the risk of nosocomial infection (P < 0.05). Multivariate log-binomial regression analysis showed that proton pump inhibitors, immunosuppressive drugs, and prior antimicrobial combination therapy were correlated with nosocomial infection. The corresponding relative risk (RR) was 1.31 (95% CI: 1.07-1.60), 1.40 (95% CI: 1.02-1.91), and 1.66 (95% CI: 1.01-2.74), respectively. Further analysis indicated that the patients with nosocomial infection had longer time in use of proton pump inhibitors and prior antimicrobial combination therapy than the patients in the control group (Z = –6.331, P < 0.001; Z = –2.667,P = 0.008). The trend Chi-square test showed that there was a dose-response relationship for proton pump inhibitors (χ² = 73.869, P < 0.001), immunosuppressive drugs (χ² = 16.530, P < 0.001), and prior antimicrobial combination therapy (χ² = 35.107, P < 0.001). Conclusions The use of immunosuppressants, proton pump inhibitors and antimicrobial combination therapy increases the risk of nosocomial infections in hospitalized patients. The prolonged use of these drugs will further increase the risk of nosocomial infection.

Objective To evaluate the performance of two immunochromatography kits (lateral flow immunoassay) in detecting carbapenemases in carbapenem-resistant Enterobacterales (CRE). Methods A total of 390 nonduplicate clinical isolates of Enterobacterales were collected and tested. The carbapenemase gene was identified by polymerase chain reaction (PCR). The five common carbapenemases were tested by two immunochromatography kits. Results Overall, 213 of the 390 Enterobacterales isolates were CRE and 177 strains were carbapenem-susceptible based on antimicrobial susceptibility testing. PCR assay confirmed that 207 of the 213 CRE strains carried carbapenemase genes, including KPC genotype in 119 strains, NDM genotype in 71 strains, IMP genotype in 9 strains, OXA-48-like genotype in 7 strains, both KPC and NDM genes in 1 strain, while none of the five common carbapenemases in 6 CRE strains. Two immunochromatography kits were used simultaneously to test the production of carbapenemases. The results of the two commercial kits were 100% consistent with PCR results. The sensitivity and specificity of the two kits were 100% (95% CI, 97.7%-100%) and 100% (95% CI, 97.4%-100%) in detection of the five carbapenemases.Conclusions The immunochromatography method is rapid and easy to operate, and can be used to detect the production of carbapenmases in clinical isolates.

Objective The clinical characteristics of 21 cases of nocardiosis were reviewed and antimicrobial resistance of Nocardia strains was analyzed in order to improve the accuracy of clinical diagnosis and treatment of nocardiosis. Methods Clinical data of patients diagnosed with nocardiosis in Zhoukou Central Hospital from 2019-2023 and the corresponding results of antimicrobial susceptibility testing were retrospectively analyzed to summarize the clinical characteristics and outcomes of patients. Results Overall, the 21 cases of nocardiosis included 9 males and 12 females, aged 2-91 years. Underlying disease was reported in 15 patients. Most common type of nocardiosis was pulmonary nocardiosis in 15 cases, followed by skin and soft tissue infection, pleurisy, lymphadenitis, and disseminated nocardiosis. Laboratory tests showed increased levels of WBC, neutrophils percentage, erythrocyte sedimentation rate, C-reactive protein, and procalcitonin. The 21 strains of Nocardia included 4 strains of Nocardia cyriacigeorgica, 2 strains each of Nocardia brasiliensis, Nocardia abscessus, Nocardia asiatica, Nocardia otitidiscaviarum and Nocardia beijingensis, and 1 strain each of Nocardia puris, Nocardia asteroides, Nocardia farcinica, Nocardia pneumoniae, Nocardia amamiensis, and 2 strains of unclassified Nocardia. All of the Nocardia strains (100%) were susceptible to linezolid, amikacin, and trimethoprim-sulfamethoxazole, followed by various levels of susceptibility to cefotaxime, moxifloxacin, imipenem and ceftriaxone, and lower susceptibility rate to cefepime, minocycline, ciprofloxacin and clarithromycin. Antimicrobial susceptibility of Nocardia strains varied with different Nocardia species. Of the 21 patients, two were referred to other hospitals, another two died, two patients received unknown treatment, and the remaining 15 patients were improved after antibiotic treatment, including sulfonamides combined with other antibiotics in 11 cases, other antibiotics in 4 cases. Conclusions Immunocompromised patients or those with underlying diseases are more susceptible to nocardiosis. The clinical features are complex and diverse. Antimicrobial susceptibility of Nocardia strains varied with different Nocardia species. Accurate identification and antimicrobial susceptibility test are essential for prescribing effective antibiotic treatment.

Objective To investigate the distribution and antimicrobial resistance profiles of pathogenic bacteria in Children's Hospital of Hebei Province to inform reasonable use of antibiotics. Methods Antimicrobial susceptibility of the bacterial isolates was tested using Kirby-Bauer method, VITEK-2 Compact, BD Phoenix 100 automated systems, and E-test method. The results were interpreted according to the breakpoints recommended by the Clinical and Laboratory Standards Institute (CLSI) in 2022. Results were analyzed by WHONET 5.6 software. Results A total of 11 909 isolates were collected from 2020 to 2022, of which 45.1% were Gram positive organisms and 54.9% were Gram negative organisms. The prevalence of MRSA and in S. aureus and MRCNS in coagulase-negative Staphylococcus was 36.8% and 73.8%, respectively. The resistance rate of Enterococcus faecalis and Enterococcus faecium to ampicillin was 2.6% and 93.5%, respectively, while the resistance rates of E. faecalis and E. faecium to high concentration gentamicin was 42.2% and 66.2%, respectively. E. faecium showed significantly higher resistance rates to the antibiotics tested than E. faecalis. The prevalence of PRSP and PSSP was 1.7% and 95.7% respectively in the non-meningitis S. pneumoniae isolates. No vancomycin- or linezolid-resistant strains were found in Staphylococcus, Enterococcus, or Streptococcus. The prevalence of ESBLs-producing E. coli and K. pneumoniae was 47.4% and 32.3%, respectively. The prevalence of carbapenem-resistant E. coli and K. pneumoniae was 2.0% and 22.4%, respectively. The prevalence of carbapenem-resistant P. aeruginosa (CRPA) and carbapenem-resistant A. baumannii (CRAB) was 9.5% and 22.1%, respectively. The resistance rate of Haemophilus influenzae to ampicillin was 83.8%. The prevalence of β-lactamase-producing H. influenzae and β-lactamase-non-producing ampicillin-resistant (BLNAR) H. influenzae was 76.1% and 7.7%, respectively. No meropenem-resistant strains were found in H. influenzae. Majority (98.0%) of Moraxella catarrhalis strains produced β-lactamase. Conclusions Multi-drug resistant bacterial pathogens are still serious in pediatric inpatients. The common clinical isolates showed various levels of resistance to different antimicrobial agents. It is important to continue the surveillance of bacterial resistance in children, take proactive measures to curb the spread of drug-resistant bacteria, and use antibiotics rationally.

Objective To investigate the distribution and antibiotic resistance profiles of clinical isolates in Beijing Children’s Hospital, Capital Medical University from 2016 to 2022. Methods All the strains isolated from inpatients in Beijing Children’s Hospital during the period from 2016 to 2022 were analyzed. Antimicrobial susceptibility test was conducted by Kirby-Bauer method or automated system. Results were interpreted according to the breakpoints recommended in the CLSI M100 2022 edition. Results A total of 24 904 isolates were analyzed, including Gram-positive bacteria (49.4%) and Gram-negative bacteria (50.6%). The top three Gram-positive bacteria were Staphylococcus aureus (15.6%), coagulase-negative Staphylococcus (14.0%), and Streptococcus pneumoniae (8.9%). The top three Gram-negative bacteria were Klebsiella spp. (8.6%), Pseudomonas aeruginosa (8.6%), and Haemophilus influenzae (8.1%). The prevalence of methicillin-resistant strains was 30.9 % in S. aureus (MRSA) and 82.7% in coagulase-negative Staphylococcus (MRCNS). The prevalence of PRSP was 75.0% (24/32) in meningitis isolates and 2.6% (57/2 195) in non-meningitis isolates. Five strains of E. faecium and 10 strains of E. faecalis were found resistant to linezolid. Two strains of E. faecium were resistant to vancomycin. The prevalence of extended-spectrum beta-lactamases (ESBLs) and carbapenem-resistant strains (CREco) in E. coli isolates was 69.0% and 9.7%, respectively. The prevalence of ESBLs and carbapenem-resistant strains (CRKpn) in K. pneumoniae isolates was 73.7%, and 37.2%, respectively. The prevalence of carbapenem-resistant strains was 21.9% in P. aeruginosa isolates and 59.3% in A. baumannii isolates. β-lactamase was detected in 68.3 % of the H. influenzae isolates. Conclusions Antimicrobial resistance is still serious in children. It is necessary to strength the surveillance of bacterial resistance and use antibiotics rationally in order to curb the spread of drug-resistant strains.

Objective To develop and validate an efficient and simple liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for determination of polymyxin E in human plasma, and apply the established method in therapeutic drug monitoring (TDM) of polymyxin E. Methods The LC-MS/MS platform was based on AB SCIEX HPLC-4500MD system. Gradient elution was performed with 0.2% formic acid in water and 0.2% formic acid in acetonitrile. Phenomenex Kinetex XB-C18 column (100 mm × 2.1 mm, 2.6 μm) were used. The analytes were detected by electrospray ionization (ESI) positive multiple reaction monitoring mode. The ion pairs for analytes (polymyxins E1, E2) and internal standard (polymyxins B1) were m/z 390.7→101.3, m/z 386.0→101.2, and m/z 402.3→101.2, respectively. Plasma samples were processed with protein precipitation method. Results Polymyxin E1 and E2 showed good linearity in the range of 0.031 2 - 6.24 mg/L and 0.006 15 - 1.23 mg/L, respectively. The within-run accuracy of polymyxin E1 and E2 in plasma ranged from 89.4% to 99.8% and 91.5% to 108.2%, respectively, while the between-run accuracy ranged from 91.8% to 104.7% and 95.6% to 105.2%, respectively. The within-run precision of polymyxin E1 and E2 in plasma ranged from 4.9% to 8.9% and 2.8% to 8.5%, respectively, while the between-run precision ranged from 4.1% to 7.6% and 4.2% to 9.8%, respectively. The average internal standard normalized matrix effect factors of polymyxins E1 and E2 were 96.9%-111.2% and 106.1%-112.8% in blank plasma samples from 6 different sources, 102.5%-106.8% and 98.8%-105.2% in lipemic plasma, respectively, 107.8%-108.9% and 106.9%-107.4% in hemolyzed plasma, respectively. The precision of matrix effects was less than 15.0%. The average recovery rate was 102.9% - 107.5% for polymyxin E1 and E2, and 107.0% for internal standard polymyxin B1. The precision was less than 3.7%. Conclusions In this study, a simple and efficient LC-MS/MS method was established for determination of polymyxin E1 and E2 in human plasma, which is reliable in the therapeutic drug monitoring and pharmacokinetic study of polymyxin E.