Biomedical subjects

Yingchun Xu

Publications and source records attributed to Yingchun Xu.

7 recordsLinked to original sources

PubMed2025

In vitro activity of contezolid and other comparators against clinical Staphylococcus and Enterococcus: a multicenter study in China.

OBJECTIVE: To evaluate the in vitro activity of contezolid against clinical Staphylococcus and Enterococcus isolates from across China, and compare its performance with linezolid and other key agents. METHODS: A total of 2510 non-duplicate Gram-positive cocci isolates were collected from 70 hospitals in seven Chinese regions. Minimum inhibitory concentrations (MICs) were determined using broth microdilution (BMD) per CLSI guidelines. MIC50/90 values, susceptibility rates, cumulative MIC curves and MIC distribution agreement between contezolid and linezolid were assessed. Linezolid-resistant isolates and contezolid-resistant isolates-defined as those based on CLSI 2025 linezolid breakpoints-underwent whole-genome sequencing and comprehensive screening for known oxazolidinone resistance determinants, including acquired resistance genes, 23S rRNA mutations and amino acid substitutions in ribosomal proteins L3, L4 and L22. RESULTS: Contezolid exhibited potent in vitro activity, with >99% of isolates inhibited at ≤4 mg/L and showed lower MIC50/90 than linezolid, with a consistently left-shifted cumulative MIC distribution. Cohen's kappa analysis supporting enhanced activity of contezolid. Notably, we report for the first time clinical isolates with contezolid MICs up to 16 mg/L. Whole-genome analysis of 14 linezolid-resistant isolates (including five resistant to contezolid) revealed universal presence of optrA, cfr, fexA and other resistance genes, alongside domain V 23S rRNA mutations and substitutions in ribosomal proteins L3 and L4, supporting a shared genetic basis and potential cross-resistance between the two agents. CONCLUSIONS: Contezolid demonstrated potent and consistent activity against drug-resistant Gram-positive cocci, supporting its potential as a therapeutic alternative to linezolid. Further studies are needed to confirm resistance mechanisms and clinical utility.

Microbial Sensitivity Tests↗

PubMed2024

Adaptation for Staphylococcus aureus to hosts via insertion mutation in the accessory gene regulator agrC gene: decreased virulence and enhanced persistence capacity.

UNLABELLED: Staphylococcus aureus is an important human pathogen due to its vast array of virulence factors regulated by multiple regulatory mechanisms, including the accessory gene regulator. In this study, two S. aureus strains were simultaneously isolated from the blood of a febrile patient, belonging to the same clone, designated as 23H with a complete hemolytic phenotype, and 23B, exhibiting an incomplete hemolytic phenotype. The genomic comparison between strains 23B and 23H revealed that 23B had a single adenine base insertion at position 923 in the agrC gene, leading to a functional loss of the encoded AgrC. Experimental findings showed that strain 23B had decreased hemolytic activity, lower cytotoxicity against human alveolar epithelial A549 cells and in the Galleria mellonella model, and a reduced ability to survive intracellularly after infecting macrophages, in comparison to 23H. Conversely, 23B exhibited enhanced biofilm formation, greater adherence to A549 cells, and increased persistence in the face of vancomycin and daptomycin treatment. Transcriptomic analysis revealed that 23B upregulated surface protein-encoding genes while simultaneously reducing the expression levels of virulence factors, highlighting the intricate regulatory adjustments facilitating its persistence and reducing pathogenic potential. ATP assay results indicated that 23B maintained elevated ATP levels during the exponential phase yet exhibited reduced levels in the stationary phase when compared with 23H. Our findings suggested that the mutation in the agrC gene of S. aureus results in diminished virulence but markedly enhances persistence. This mutated strain warrants clinical attention because it may lead to treatment failures and persist in patients. IMPORTANCE: In clinical antimicrobial therapy, bacterial strains often develop resistance to antimicrobial agents. Additionally, mutations in their gene regulatory networks can increase their persistence, especially in immunocompromised patients. This study identified an insertion mutation in the accessory gene regulator, agrC gene, carried by a Staphylococcus aureus strain isolated from the blood of a febrile patient, leading to the functional loss of AgrC. Further research revealed that despite the reduced virulence of the mutated strain, it significantly bolstered the capacity to adapt and endure within the host during prolonged infections. This was evidenced by increased adhesion and biofilm formation capabilities, development of antimicrobial tolerance, and decreased ATP levels linked to persistence. Therefore, monitoring these mutations in S. aureus is crucial clinically, as they can complicate treatment strategies.

Staphylococcus aureus↗

PubMed2006

Study on atherosclerosis treated with theory of detoxification.

Starting with the contents, classification and pathogenic characteristics of the toxic pathogen and combining the modern medical research on the correlation of atherosclerosis with inflammation and immune reaction, authors have studied and expounded the interrelationship between the toxic pathogen and atherosclerosis. The toxic pathogen affecting the whole pathological process of atherosclerosis is a key factor for the disease to remain lingering and a cause of various cardiocerebrovascular diseases. Detoxification can be used to treat atherosclerosis so as to enhance the toxin-removing ability of the body and resist the damage to the body from the toxic pathogen.

Atherosclerosis↗

PubMed2005

Increased risk of cancer among relatives of patients with lung cancer in China.

BACKGROUND: Genetic factors were considered as one of the risk factors for lung cancer or other cancers. The aim of this work was to determine whether a genetic predisposition accounts for such familial aggregation of cancer among relatives of lung cancer probands. METHODS: A case-control study was conducted in 800 case families identified by lung cancer patients (probands), and in 800 control families identified by the probands'spouses. The data were analysed with logistic regression analysis model. RESULTS: The data revealed a significantly greater overall risk of cancer (OR = 1.82, P < 0.01) in the proband group. The relatives of lung cancer probands maintained an increased risk of non-lung cancer (P < 0.05) after adjusting for confounder factors. The crude odds ratio of a proband family having one family member with cancer was 1.67 compared with control families. Proband families were 2.56 times more likely to have two other family members with cancer. For three cancers and four or more cancers, the risk increased to 3.50 and 5.91, respectively. The most striking differences in cancer prevalence between proband and control families were noted for cancer risk among female relatives. The strongest effects were for not only lung cancer in any female relatives (OR 2.17, 95%CI 1.60-3.64) and mothers (OR 2.78, 95%CI 1.23-5.12) and sisters (OR 2.03, 95%CI 1.26-3.97), but also non-lung cancer in females and mothers (OR 2.00, 95%CI 1.26-3.01, and OR 2.34, 95%CI 1.28-4.40, respectively). CONCLUSION: These data support the hypothesis of a genetic susceptibility to cancer in families with lung cancer, and the female genetic susceptibility to cancer might be greater than male.

Adult↗

PubMed2002

Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae bloodstream infection: risk factors and clinical outcome.

OBJECTIVES: To study the risk factor for nosocomial bacteremia caused by Escherichia coli or Klebsiella pneumoniae producing extended-spectrum beta-lactamase (ESBL) and the influence on patient outcome. DESIGN: Retrospective, single-center study of consecutive bacteremic patients. SETTINGS: A university-affiliated teaching hospital. PATIENTS: A total of 85 patients with nosocomial bacteremia due to E. coli or K. pneumoniae were enrolled. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: The demographic characteristics and clinical information including treatment were recorded upon review of patients' records. The primary end point was hospital mortality. Twenty-seven percent of isolates produced ESBLs. Previous treatment with 3rd-generation cephalosporins was the only independent risk factor for bacteremia due to ESBL-producing pathogens [odds ratio (OR) 4.146, P=0.008]. Antibiotic treatment was considered appropriate in 71 cases (83%), and failed in 23 patients (27%). Twenty-one patients (25%) died in the hospital. Antibiotic treatment failure was the only independent risk factor for hospital mortality (OR 15.376, P=0.001). Inappropriate antibiotic treatment might lead to significantly higher mortality rate (7/14 vs 14/71, P=0.016). Patients treated with imipenem were more likely to survive while those receiving cephalosporin treatment tended to have a poorer outcome (1/19 vs 14/40, P=0.023). CONCLUSIONS: More judicious use of cephalosporins, especially 3rd-generation cephalosporins, may decrease ESBL-producing E. coli or K. pneumoniae bacteremia, and also improve patient outcome.

APACHE↗

PubMed2002

[Correlations between atopy and airway hyperresponsiveness].

To determine the correlations between atopy and airway hyperresponsiveness(AHR), 3000 nuclear families were selected by indicator case of asthma. All of questionaire, methacholine challenge test(5 g/L) and skin test(with 12 allergens) were conducted among all relatives in those nuclear families. The data were analysed through the EP15.01 and SAS6.12 and the odds ratio(OR) was obtained. The results of the skin prick tests on 12,516 relatives of the asthma nuclear families declared that the percentages of the positive erythema and rash were 12.5% and 51.3%, respectively. Furthermore, the positive rate of male was higher than that of female(P < 0.01). At the meantime, the positive rate under age of 35 was higher than that of people with the age over 35(P < 0.01). The prevalence of AHR was 11.9% among all relatives, in which the positive erythema and rash were 15.5% and 12.7%, respectively. Both the positive erythema and rash increased the risk of AHR, and their odds ratio are 1.17 and 1.14(P < 0.01), respectively, and the risk of AHR was greater with the increasing of kind of allergens causing the positive erythema or rash. The AHR was related with positive skin prick.

Adult↗

PubMed2002

[Phenological analysis upon yield and quality of Flos Lonicerae].

Yield and quality of Flos Lonicerae varied in different phenological phase. Yield in the first flowering season was the highest. Yield in the last three flowering season decreased one by one. The dry weight of one thousand flower buds and chlorogenic acid content in the first flowering season were the highest during a year, then was the fourth, the second and the third were both the lower. The difference of above was related to such biologic factors as days of flower bud differentiation, types of flower branch, leaf area, chlorophyll content, and also to such climatic factors as air temperature, hours of sunshine and precipitation.

Chlorogenic Acid↗