Microporous PdCuB nanotag-based electrochemical aptasensor with Au@CuCl2 nanowires interface for ultrasensitive detection of PD-L1-positive exosomes in the serum of lung cancer patients.

Programmed cell death ligand 1 protein-positive (PD-L1+) exosomes have been found to be a potential biomarker for the diagnosis of non-small cell lung cancer (NSCLC). However, the development of highly sensitive detection technique for PD-L1+ exosomes is still a challenge in clinical applications. Herein, a sandwich electrochemical aptasensor based on ternary metal-metalloid palladium-copper-boron alloy microporous nanospheres (PdCuB MNs) and Au@CuCl2 nanowires (NWs) was designed for the detection of PD-L1+ exosomes. The excellent peroxidase-like catalytic activity of PdCuB MNs and the high conductivity of Au@CuCl2 NWs endow the fabricated aptasensor with intense electrochemical signal, thus enabling the detection of low abundance exosomes. The analytical results revealed that the aptasensor maintained favorable linearity over a wide concentration range of 6 orders of magnitude and reached a low detection limit of 36 particles/mL. The aptasensor is successfully applied to the analysis of complex serum samples and achieves the accurate identification of clinical NSCLC patients. Overall, the developed electrochemical aptasensor provides a powerful tool for early diagnosis of NSCLC.

Longitudinal Serum Proteome Characterization of COVID-19 Patients With Different Severities Revealed Potential Therapeutic Strategies.

The COVID-19 pandemic caused by SARS-CoV-2 is exerting huge pressure on global healthcare. Understanding of the molecular pathophysiological alterations in COVID-19 patients with different severities during disease is important for effective treatment. In this study, we performed proteomic profiling of 181 serum samples collected at multiple time points from 79 COVID-19 patients with different severity levels (asymptomatic, mild, moderate, and severe/critical) and 27 serum samples from non-COVID-19 control individuals. Dysregulation of immune response and metabolic reprogramming was found in severe/critical COVID-19 patients compared with non-severe/critical patients, whereas asymptomatic patients presented an effective immune response compared with symptomatic COVID-19 patients. Interestingly, the moderate COVID-19 patients were mainly grouped into two distinct clusters using hierarchical cluster analysis, which demonstrates the molecular pathophysiological heterogeneity in COVID-19 patients. Analysis of protein-level alterations during disease progression revealed that proteins involved in complement activation, the coagulation cascade and cholesterol metabolism were restored at the convalescence stage, but the levels of some proteins, such as anti-angiogenesis protein PLGLB1, would not recovered. The higher serum level of PLGLB1 in COVID-19 patients than in control groups was further confirmed by parallel reaction monitoring (PRM). These findings expand our understanding of the pathogenesis and progression of COVID-19 and provide insight into the discovery of potential therapeutic targets and serum biomarkers worth further validation.

Profile of Immunoglobulin G N-Glycome in COVID-19 Patients: A Case-Control Study.

Coronavirus disease 2019 (COVID-19) remains a major health challenge globally. Previous studies have suggested that changes in the glycosylation of IgG are closely associated with the severity of COVID-19. This study aimed to compare the profiles of IgG N-glycome between COVID-19 patients and healthy controls. A case-control study was conducted, in which 104 COVID-19 patients and 104 age- and sex-matched healthy individuals were recruited. Serum IgG N-glycome composition was analyzed by hydrophilic interaction liquid chromatography with the ultra-high-performance liquid chromatography (HILIC-UPLC) approach. COVID-19 patients have a decreased level of IgG fucosylation, which upregulates antibody-dependent cell cytotoxicity (ADCC) in acute immune responses. In severe cases, a low level of IgG sialylation contributes to the ADCC-regulated enhancement of inflammatory cytokines. The decreases in sialylation and galactosylation play a role in COVID-19 pathogenesis via the activation of the lectin-initiated alternative complement pathway. IgG N-glycosylation underlines the complex clinical phenotypes of SARS-CoV-2 infection.

Rapid Detection of COVID-19 Using MALDI-TOF-Based Serum Peptidome Profiling.

The outbreak of coronavirus disease 2019 (COVID-19) caused by SARS CoV-2 is ongoing and a serious threat to global public health. It is essential to detect the disease quickly and immediately to isolate the infected individuals. Nevertheless, the current widely used PCR and immunoassay-based methods suffer from false negative results and delays in diagnosis. Herein, a high-throughput serum peptidome profiling method based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is developed for efficient detection of COVID-19. We analyzed the serum samples from 146 COVID-19 patients and 152 control cases (including 73 non-COVID-19 patients with similar clinical symptoms, 33 tuberculosis patients, and 46 healthy individuals). After MS data processing and feature selection, eight machine learning methods were used to build classification models. A logistic regression machine learning model with 25 feature peaks achieved the highest accuracy (99%), with sensitivity of 98% and specificity of 100%, for the detection of COVID-19. This result demonstrated a great potential of the method for screening, routine surveillance, and diagnosis of COVID-19 in large populations, which is an important part of the pandemic control.

Carbapenem-Resistant Enterobacter cloacae Causing Nosocomial Infections in Southwestern China: Molecular Epidemiology, Risk Factors, and Predictors of Mortality.

BACKGROUND: The emergence and spread of carbapenem-resistant Enterobacter cloacae (CR-ECL) have posed a serious threat to clinical management. This retrospective study assessed the epidemiological characteristics of CR-ECL to explore the risk factors and predictors of mortality in patients with CR-ECL infection. METHODS: We performed a retrospective 1:2 case-control study of hospitalized patients from January 2014 to December 2017. A total of 85 consecutive unique CR-ECL strains comprised the case group, and 170 matched patients with carbapenem-susceptible Enterobacter cloacae (CS-ECL) infection at the same period as the control group. Isolates were screened for potential resistance genes by polymerase chain reaction (PCR) and molecular typing was performed by multilocus sequence typing (MLST). RESULTS: The results of drug resistance gene detection showed that blaNDM-1 was the most common carbapenem resistance gene. The MLST results showed that ST51 was the predominant epidemic type, followed by ST88. ICU admission (P<0.001), drainage tube (P=0.002), central venous catheter (P=0.005), and carbapenem exposure (P=0.003) were independent risk factors for CR-ECL infection. Significant predictors for 28-day mortality included solid tumours (P=0.005), septic shock (P=0.019), and mechanical ventilation (P=0.027). CONCLUSION: Our study indicated that ST51 and ST88, which are closely related, were the predominant epidemic types of CR-ECL producing blaNDM-1 in southwestern China. Strengthening the surveillance of patients with solid tumours, septic shock and mechanical ventilation is an urgent need.

Molecular Epidemiology of and Risk Factors for Extensively Drug-Resistant Klebsiella pneumoniae Infections in Southwestern China: A Retrospective Study.

Background: The increasing prevalence of extensively drug-resistant Klebsiella pneumoniae (XDR-KP) poses a serious threat to clinical anti-infective treatment. This retrospective study assessed the molecular epidemiology of and risk factors for infections with XDR-KP to investigate the mechanism of drug resistance and the epidemiological characteristics. Methods: A retrospective 1:2 case-control study was conducted at Chongqing Renji Affiliated Hospital of the Chinese Academy of Sciences University from January 2015 to December 2017. A total of 69 non-repetitive XDR-KP strains were collected. Patients infected with XDR-KP comprised the case group, and 138 matched patients with non-XDR-KP infection at the same site comprised the control group. The chi-square test and logistic regression were performed to evaluate the related risk factors. Molecular typing was performed by multilocus sequence typing (MLST). Potential resistance genes were detected by polymerase chain reaction (PCR) and sequencing. Predictors of 28-day mortality in patients with XDR-KP infection were also identified in our study. Results: Only tigecycline and polymyxin B showed favorable in vitro drug sensitivity tests. These XDR-KP strains had a high prevalence rate (n = 66, 95.7%) of carbapenemase-related drug resistance genes. Among them, KPC-2 was the most frequently detected gene (n = 52, 75.4%). Particularly, all of the isolates harbored multiple drug resistance genes. Epidemiological analysis showed that fifty-eight XDR-KP isolates were resistant strains with the ST-11 genotype. Multivariate logistic regression analysis showed that ICU admission (OR: 3.28, 95% CI: 1.66-6.49, P < 0.001), tracheal cannula (OR: 3.16, 95% CI: 1.48-6.76, P = 0.003), and carbapenem exposure (OR: 3.16, 95% CI: 1.25-7.98, P = 0.015) were independent risk factors for XDR-KP infection. Solid tumors (OR: 7.22, 95% CI: 1.84-28.34, P = 0.005) and septic shock (OR: 9.46, 95% CI: 2.00-44.72, P = 0.005) were independent risk factors for 28-day mortality from XDR-KP infection. Conclusion: This study showed that XDR-KP isolates were highly resistant and exhibited clonal transmission. ST11 was the predominant epidemic type of XDR-KP producing KPC-2 in Southwestern China. Physicians should be aware of these high-risk patients with notable predictive factors for XDR-KP infection. These findings may provide some recommendation for the diagnosis and treatment of patients infected with XDR-KP strains in Southwestern China.

l-Serine potentiates fluoroquinolone activity against Escherichia coli by enhancing endogenous reactive oxygen species production.

BACKGROUND: The increase in multiple antimicrobial-resistant bacteria seriously threatens global public health. Novel effective strategies are urgently needed. l-Serine was reported as the most effective amino acid inhibitor against bacterial growth and can sensitize Escherichia coli cells to gentamicin. It is currently unknown whether l-serine affects other type of antibiotics such as ß-lactams and fluoroquinolones. METHODS: Using E. coli, we studied the combination of l-serine with diverse antibiotics against laboratory and clinical E. coli cultures and persisters. The intracellular NAD(+)/NADH level and ROS were determined using kits. Total cellular iron was determined by using a colorimetric ferrozine-based assay. RESULTS: Exogenous l-serine sensitized E. coli ATCC 25922 and clinically isolated fluoroquinolone-resistant E. coli to fluoroquinolones. This potentiation is independent of growth phase. Addition of serine increases the production of NADH. The underlying mechanism of this strategy is that the combination of serine with ofloxacin or moxifloxacin increases the NAD(+)/NADH ratio, disrupts the Fe-S clusters and increases the production of endogenous reactive oxygen species. Furthermore, we used a serine and ofloxacin or moxifloxacin combination in vitro to combat bacterial persister cells, compared with antibiotic treatment alone; combinational treatments of persister cells with antibiotics and l-serine resulted in a significantly greater decrease in cell viability. CONCLUSIONS: To our knowledge, this is the first report that l-serine can potentiate the action of ofloxacin or moxifloxacin against Gram-negative bacteria and could constitute a new strategy for the eradication of bacterial infections.

Intriguing arms race between phages and hosts and implications for better anti-infectives.

Phages are viruses of bacteria. The interaction between phages and bacteria shall boost both parties' evolution. During the lengthy coevolution, the host has evolved multiple mechanisms against the phages. The phages also have evolved unique strategies to facilitate their own survival accordingly. This article summarizes the measures and countermeasures employed by the both parties and their implications for better biomedicines.

Proteomic insights into Acinetobacter baumannii drug resistance and pathogenesis.

Acinetobacter baumannii is an important opportunist pathogen, due to severe antibiotic resistance and nosocomial infection. The epidemiology and antibiotic resistance of A.baumannii have been extensively reviewed, but the pathogenesis and virulence remain unclear. Proteomics analysis has been applied to study the mechanism of drug resistance, biofilm, micronutrient acquisition, and the extracellular compartment. This review summarizes applications of proteomics in A. baumannii, aiming to summarize novel insights into the mechanism of A. baumannii pathogenesis and drug resistance.

[Diagnosis and therapy of 186 spontaneous bacterial peritonitis patients with end-stage liver disease].

OBJECTIVE: To improve the diagnosis and treatment level of spontaneous bacterial peritonitis (SBP) in the patients with advanced liver disease, get better curative effect and prognosis. METHODS: Registered the body temperature, symptoms and signs in the abdomen, and blood routine test, the polymorphonuclear (PMN) cell count, and ascites culture in the patients with cirrhosis and fulminant hepatitis. These patients were given supporting therapies including use plasma and albumin as well as antibiotics treatment according to drug sensitivity or empiric. Changes of the body temperature, symptoms and signs were used to evaluate the effect of therapy. RESULTS: 186 of 275 inward patients with end-stage liver disease during this period were considered as SBP by ascites culture or clinical experience with various degree symptoms and signs such as pain, distention, higher tension and touch pain in the abdomen. Infective rate was 67.6%. Among them 138 patients had abnormal body temperature more than 37.4 degrees C. 106 patients with leukocyte count in the peripheral blood more than 10 x 10(9)/L; 137 patients with PMN more than 80% in differential cell count; 103 patients with PMN more than 250/mm(3) in ascites. Only 29 patients were culture positive. 82 patients were cured, 17 patients with improvement, 18 patients with inefficacy or deterioration. 42 patients died of hepatic-renal failure and 27 patients died because of upper alimentary tract bleeding, respectively. CONCLUSION: Signs and symptoms of SBP were atypical in the patients with end-stage liver disease. Ascites culture positive rate was not high. Early diagnosis and proper use antibiotics according to culture and empirics were important to increase effect and improve prognosis