Phase transition-driven encapsulation of biomolecules using liquid metal with on-demand release for biomedical applications.

Robust encapsulation and controllable release of biomolecules have wide biomedical applications ranging from biosensing, drug delivery to information storage. However, conventional biomolecule encapsulation strategies have limitations in complicated operations, optical instability, and difficulty in decapsulation. Here, we report a simple, robust, and solvent-free biomolecule encapsulation strategy based on gallium liquid metal featuring low-temperature phase transition, self-healing, high hermetic sealing, and intrinsic resistance to optical damage. We sandwiched the biomolecules with the solid gallium films followed by low-temperature welding of the films for direct sealing. The gallium can not only protect DNA and enzymes from various physical and chemical damages but also allow the on-demand release of biomolecules by applying vibration to break the liquid gallium. We demonstrated that a DNA-coded image file can be recovered with up to 99.9% sequence retention after an accelerated aging test. We also showed the practical applications of the controllable release of bioreagents in a one-pot RPA-CRISPR/Cas12a reaction for SARS-COV-2 screening with a low detection limit of 10 copies within 40 min. This work may facilitate the development of robust and stimuli-responsive biomolecule capsules by using low-melting metals for biotechnology.

Clone dissemination of IncX3 plasmid carrying blaNDM-1 in ST76 carbapenem resistance Klebsiella pneumoniae and bactericidal efficiency of aztreonam combined with avibactam in vitro and in vivo.

OBJECTIVES: The rapid spread of the New Delhi Metal-ß-lactamase-1 (NDM-1) gene in Klebsiella pneumoniae poses a substantial challenge to pediatric therapeutic care. Here, we aimed to characterise the IncX3-type plasmid carrying the blaNDM-1 gene in ST76 carbapenem resistance K. pneumoniae (CRKP) strains and assess the in vitro and in vivo bactericidal efficacy of Aztreonam (ATM) combined with Avibactam (AVI) (ATM+AVI) against CRKP. METHODS: The broth microdilution method and PCR were used to detect antimicrobial susceptibility and antibiotic resistance genes. Genetic relatedness was determined using Pulsed-Field Gel Electrophoresis (PFGE) and Multilocus Sequence Typing (MLST). The plasmid conjugation assay was used to verify the transmissibility of drug-resistant plasmids. Whole-Genome Sequencing (WGS) was employed to elucidate the genomic attributes of the genes. The Fractional Inhibitory Concentration (FIC) was calculated based on the checkerboard titration assay to determine the antimicrobial effect of ATM+AVI. The time-kill curve assay and a mouse anti-infection model were used to investigate the in vitro and in vivo bactericidal efficiency of ATM+AVI. RESULTS: Seven blaNDM-1-producing strains were found to be highly resistant to carbapenems, and they all belonged to the same sequence type (ST76) and were classified into the same PFGE clusters with an 89.1% similarity. The conjugation assay showed that the blaNDM-1-carrying plasmid was successfully transferred to Escherichia coli 600, resulting in transconjugants with carbapenem antibiotic resistance. A 54-kb IncX3 plasmid (pNDM-XZA88) carried the blaNDM-1 gene located on a Tn125 transposon-like element structure, demonstrating the transferability of resistance genes. Genome comparative analysis revealed that pNDM-XZA88 was highly similar to pCQ17 × 3 and pRor-30818cz and had relatively conserved backbones and variable accessory regions compared to the other four plasmids (pC39-334 kb, pNDM-1-DY1928, pNDM-K725, and pNDM-Z244). The checkerboard titration and time-kill curve assays revealed that the ATM+AVI combination therapy exerted significant bactericidal efficacy against the blaNDM-1-producing strains in vitro. The ATM+AVI combination also significantly reduced the bacterial burden in a mouse infection model constructed using the blaNDM-1-producing K. pneumoniae. CONCLUSION: This study demonstrated the clone dissemination of blaNDM-1-harboring IncX3 plasmids among the ST76 K. pneumoniae isolated from pediatric patients. Therefore, more attention should be paid to preventing this high-risk clone from harming pediatric patients. Moreover, we deduced that the ATM+AVI combination therapy is an effective strategy for treating blaNDM-1-producing K. pneumoniae.

Mn-N-C catalysts derived from metal triazole framework with hierarchical porosity for efficient oxygen reduction.

Manganese and nitrogen co-doped porous carbon (Mn-N-C) are proposed as one of the most up-and-coming non-precious metal electrocatalysts to substitute Pt-based in the oxygen reduction reaction (ORR). Herein, we chose metal triazole frameworks as carbon substrate with hierarchical porosity for trapping and anchoring Mn-containing gaseous species by a mild one-step pyrolysis method. The optimized Mn-N-C electrocatalyst with a large metal content of 1.71 wt% and a volume ratio of 0.86 mesopores pore delivers a superior ORR activity with a half-wave potential (E1/2) of 0.92 V in 0.1 M KOH and 0.78 V in 0.1 M HClO4. Moreover, the modified Mn-N-C catalyst showed superior potential cyclic stability. TheE1/2remained unchanged in 0.1 M KOH and only lost 6 mV in 0.1 M HClO4after 5000 cycles. When applied as the cathode catalyst in Zn-air battery, it exhibited a maximum peak power density of 176 mW cm-2, demonstrating great potential as a usable ORR catalyst in practical devices.

High-performance manganese and nitrogen codoped carbon (Mn-N-C) oxygen reduction electrocatalyst from Mn2+coordinated sodium alginate.

The research on low-cost, high-performance non platinum group metal (PGM) oxygen reduction reaction (ORR) catalysts is of great significance for the rapid promotion of fuel cells' practical applications. In this work, Mn-N-C catalyst with outstanding activity was prepared through using hydrogel formed by coordination of sodium alginate (SA) and Mn2+as the precursor. During the preparation process, g-C3N4was added to improve the surface area enrich the pore structure of catalysts, as well as to function as the nitrogen source. Compare with commercial Pt/C catalyst, the optimum Mn-N-C catalyst possesses extraordinary ORR activity in alkaline electrolytes, with a half-wave potential (E1/2) of 0.90 V. In addition, the Mn-N-C catalyst also displays exceptional stability in alkaline and acidic electrolytes, much superior to Pt/C catalyst.

Phenotypic and genotypic characterisation of linezolid-resistant coagulase-negative staphylococci possessing cfr-carrying plasmid.

OBJECTIVES: Linezolid-dependent growth has contributed to wide dissemination of Staphylococcus epidermidis in hospitals. This study aimed to characterise linezolid-resistant coagulase-negative staphylococci (CoNS) isolates and the possibility of linezolid dependence in China. METHODS: Phenotypic and genotypic resistance of 13 CoNS isolates were investigated by antimicrobial susceptibility testing and PCR. Similarity of isolates was determined by pulsed-field gel electrophoresis (PFGE). Characterisation of the cfr-carrying plasmid was performed by S1 nuclease PFGE, Southern blotting and whole-genome sequencing (WGS). A maximum likelihood phylogenetic tree was constructed for phylogenetic analysis. Growth curve analysis was performed with and without linezolid to determinate the possible contribution of linezolid dependence to linezolid-resistant CoNS dissemination. RESULTS: Thirteen CoNS isolates showed linezolid MICs of 8 mg/L to >256 mg/L, typed into three PFGE profiles. Southern blotting and WGS indicated that the cfr gene was located on a 39.5-kb plasmid with 99% identity to cfr-harbouring plasmids pSR01, pLRSA417 and pH29-46. The cfr gene was flanked by two copies of an IS256-like element ISEnfa4 family transposase, indicating the transferability of linezolid resistance conferred by the cfr gene. Comparative phylogenetic analysis revealed that Staphylococcus capitis XZ03 shared high similarity with linezolid-resistant S. capitis isolates in Huashan Hospital, Shanghai. Thirteen CoNS isolates did not exhibit linezolid dependence on exposure from 8-32 mg/L. CONCLUSION: The endemic CoNS clone carrying the cfr gene in our hospital showed high-level linezolid resistance, threatening linezolid use. Linezolid-dependent growth under linezolid selective pressure was not observed, indicating that it may not yet be a common phenotype in Staphylococcus spp.

Clinical Molecular Epidemiology of Carbapenem-Resistant Klebsiella pneumoniae Among Pediatric Patients in Jiangsu Province, China.

PURPOSE: The continuous emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) has become a serious public health problem globally, especially for children, but data on CRKP infection in pediatric patients are limited. This study aimed to identify epidemiological and molecular patterns of CRKP among pediatric patients in Jiangsu province, China. PATIENTS AND METHODS: CRKP were consecutively collected from the Children's Hospital of Nanjing Medical University in China from July 2018 to May 2019. Then, CRKP strains were performed for further study: antimicrobial susceptibility testing, drug-resistance determinants screening and homology analysis. RESULTS: We collected 94 CRKP from 94 children. Overall, bla KPC-2 (79.8%) was the predominant carbapenemase gene, followed by bla NDM-1(14.9%), bla IMP-4 (5.3%) and bla NDM-5(4.3%). Notably, two isolates coharbored bla KPC-2 and bla IMP-4, and two isolates coharbored bla KPC-2 and bla NDM-5. MLST analysis revealed that 14 distinct sequence types (STs) were identified, of which ST11 was the most common sequence type identified. Moreover, two novel STs, ST4854 and ST4855, were detected in this study. PFGE revealed that a predominant cluster consisting of KPC-2-producing CRKP ST11 clone isolates was identified and was distributed mainly in the pediatric intensive care unit (PICU) and cardiac intensive care unit (CCU). Moreover, this is the first report to identify the dissemination of ST716 CRKP coproducing KPC-2 and IMP-4 clones. CONCLUSION: Clonal dissemination of KPC-2-producing CRKP ST11 was observed in multiple departments. Moreover, two novel STs (ST4854 and ST4855) were identified, which indicates an increased diversity of CRKP strains. To our knowledge, this is the first report that identified the dissemination of Klebsiella pneumoniae coproducing KPC-2 and IMP-4 clones among children, which represents a significant health risk to pediatric patients. Active surveillance and effective control measures are urgently needed to prevent further transmission of these strains among children.

Teasaponin Ameliorates Murine Colitis by Regulating Gut Microbiota and Suppressing the Immune System Response.

Background: Dietary intervention is an exciting topic in current research of inflammatory bowel disease (IBD). The effect of teasaponin (TS) on IBD has not been fully elucidated. Here, we aim to investigate the intestinal anti-inflammatory activity of TS in a dextran sodium sulfate (DSS)-induced colitis mouse model and identify potential mechanisms. Methods: We applied TS to mice with DSS-induced colitis and then monitored the body weight, disease activity index (DAI) daily. When sacrificed, the intestinal permeability was measured. The analysis of mucin and tight junction proteins was conducted. We detected the inflammatory cytokines, the immune cells and related inflammatory signaling pathways. In addition, the gut microbiota were analyzed by 16S rRNA sequencing and we also performed fecal microbiota transplantation (FMT). Results: It showed that TS ameliorated the colonic damage by lowering the DAI, prolonging the colon length, reducing inflammatory cytokines and improving the mucus barrier. Parallel to down-regulation of the inflammatory cytokines, the fecal lipocalin 2, p-P65, p-STAT3, and neutrophil accumulation were also decreased in TS-treated mice. Microbiota characterization showed that Campylobacteria, Proteobacteria, Helicobacter, and Enterobacteriaceae were the key bacteria associated with IBD. In addition, TS could reverse the Firmicutes/Bacteroidetes (F/B) ratio and increase the beneficial bacteria, including Akkermansia and Bacteroides. TS ameliorated DSS-induced colitis by regulating the gut microbiota, and the gut microbiota could regulate gut inflammation. Conclusions: These studies demonstrated that TS ameliorated murine colitis through the modulation of immune response, mucus barrier and gut microbiota, thus improving gut dysbiosis. In addition, the gut microbiota may play an important role in regulating the host's innate immune system, and the two coexist and are mutually beneficial. We provide a promising perspective on the clinical treatment of IBD.

Disease burden and molecular epidemiology of carbapenem-resistant Klebsiella pneumonia infection in a tertiary hospital in China.

BACKGROUND: Carbapenem-resistant Klebsiella pneumoniae (CRKP) has become an urgent global public health issue, but its distribution has obvious regional differences. The purpose of this study was to investigate the patient-based disease burden and molecular epidemiology of CRKP infections in a tertiary hospital in northern Jiangsu Province in China. METHODS: A retrospective, epidemiological survey of CRKP infections in our hospital from January to December 2016 was conducted to collect clinical and epidemiologic data. Non-duplicated clinical CRKP isolates were collected for the resistance-associated genes and clonal correlation analysis by PCR, sequencing and multilocus sequence typing (MLST). RESULTS: 252 CRKP infection cases were collected, and the annual CRKP infection incidence of the hospital during 2016 was 14.64 per 10,000 hospital discharges (252/172,112*10,000) and 13.78 per 100,000 patient days (252/1,829,190*100,000). The patient-based disease burden concentrated on antimicrobial exposure history (133/224, 59.37%)-the most dominant STs. KPC-2 (120/128, 93.8%) was the predominant carbapenemase and ST11 (98/128, 76.5%) was the dominant STs. One isolate was detected with harboring bla KPC-2 and bla MCR-1 simultaneously. CONCLUSIONS: Patient-based disease burden and KPC-2-producing ST11 Klebsiella pneumonia caused in higher CRKP incidence in the hospital. The emergence of CRKP with bla KPC-2 and bla MCR-1 should be of concern.

First Reported Nosocomial Outbreak Of NDM-5-Producing Klebsiella pneumoniae In A Neonatal Unit In China.

PURPOSE: Carbapenem-resistant Klebsiella pneumoniae (CRKP) have emerged worldwide and also being a major threat to children and neonate. In this study, we describe a nosocomial outbreak of NDM-5-producing Klebsiella pneumoniae in neonatal unit of a teaching hospital in China from September 2015 to September 2016. PATIENTS AND METHODS: We collected 12 carbapenem-resistant K. pneumoniae outbreak strains from 12 newborns and characterized these isolates for their antimicrobial susceptibility, clone relationships, and multi-locus sequence types using vitek-2 compact system, pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Resistant genes were detected by using PCR and sequencing. Plasmid conjugation experiment was carried out to determine the transferability of carbapenem resistance. PCR-based replicon typing (PBRT), S1 nuclease-PFGE, and southern blotting were conducted for plasmid profiling. RESULTS: All 12 K. pneumoniae isolates were resistant to carbapenems and carried bla NDM-5, bla TEM-1 and bla SHV-11. Furthermore, PFGE analysis showed that NDM-5-producing K. pneumoniae were clonally related and MLST assigned them to sequence type 337. Conjugative assays showed that plasmids harboring bla NDM-5 gene were self-transmissible. Plasmid analysis suggested that all bla NDM-5 gene located on a ~45 kb IncX3 type plasmid. CONCLUSION: To the best of our knowledge, this is the first report of a clone outbreak of bla NDM-5-carrying K. pneumoniae isolates from neonates. There is an urgent need for effective infection control measures to prevent bla NDM-5 variants from becoming epidemic in the neonates in the future.

Overestimated discriminatory power of MALDI-TOF mass spectrometry for typing of carbapenem-resistant Klebsiella pneumoniae clones.

Homology surveillance of carbapenem-resistant Klebsiella pneumoniae (CRKP) is critical to monitor and prevent outbreaks of nosocomial infections. In the present study, a matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF MS)-based method was evaluated as a rapid tool for typing CRKP in comparison with pulsed-field gel electrophoresis (PFGE) and multi locus sequence typing (MLST). Drug-resistant phenotypes and genotypes of 44 CRKP isolates were detected by microdilution broth method and polymerase chain reaction, and typed by PFGE, MLST and MALDI-TOF MS. Simpson's Index of Diversity was used to evaluate taxonomic diversity, Adjusted Rand Index (ARI) for congruence between the typing methods and Wallace coefficients (W) for the ability of either method to predict each other. Forty-four CRKP isolates of 15 sequence types (STs) produced either NDM-1 (n = 16), NDM-5 (n = 9) or KPC-2 (n = 19) carbapenemases. PFGE differentiated these isolates into 16 distinct types, and two deoxyribonucleic acid profiles were assigned to ST337 and ST11, respectively. MALDI-TOF MS failed to clearly delineate between clusters on dendrograms based on principal components analysis and main spectrum profile. The chosen parameters resulted in a maximum ARI of 0.310 (95% CI 0.088-0.531) between MALDI-TOF MS typing and the PFGE reference, indicating a low ability of the former to correctly identify related isolates. Likewise, the maximum W coefficient of 0.367 (95% CI 0.203-0.532) showed that MALDI-TOF MS had a lower predictive power than PFGE. We conclude that MALDI-TOF MS lacks the discriminatory power necessary for clone assignment of CRKP isolates and consequently cannot be considered as a rapid and creditable method for this purpose.

High Prevalence of bla NDM Variants Among Carbapenem-Resistant Escherichia coli in Northern Jiangsu Province, China.

The continuous emergence of carbapenem-resistant Escherichia coli (CRECO) presents a great challenge to public health. New Delhi metallo-lactamase (NDM) variants are widely disseminated in China, so the research on the prevalence and transmission of diverse bla NDM variants is urgently needed. In the present study, 54 CRECO isolates were collected from 1,185 Escherichia coli isolates in five hospitals in Northern Jiangsu Province, China from September 2015 to August 2016. Antimicrobial susceptibility tests, PCR detection of resistance determinants, multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were performed to characterize these strains. Plasmid conjugation experiments were carried out to determine the transferability of resistant genes from selected isolates. PCR-based replicon typing (PBRT), S1 nuclease-PFGE, and Southern blotting were conducted for plasmid profiling. Carbapenemase genes were detectable in all CRECO isolates, among which thirty-one CRECO isolates were found to carry bla NDM-5 (54.7%), while, bla NDM-1, bla NDM-7, bla NDM-4, bla NDM-9, and bla KPC-2 were identified in 14, five, two, one, and one isolates, respectively. MLST results revealed 15 different STs and four new STs were first reported to be linked with NDM-producing isolates. PFGE typing showed that no more than two isolates with the same ST appeared to the same band pattern except three ST410 isolates. Twenty-six selected NDM-producing isolates were successfully transferred to E. coli J53 by conjugation experiments. Notably, 50.0% (13/26) of blaNDM variants were found to be carried by ~55 kb IncX3 plasmid. Our study reported a high prevalence of blaNDM variants, especially bla NDM-5, in Northern Jiangsu province, China. Diverse bla NDM variants were mainly carried by ~55 kb IncX3 plasmids, suggesting that the fast evolution and high transferability of this kind of plasmid promote the high prevalence of bla NDM variants. Therefore, large-scale surveillance and effective infection control measures are also urgently needed to prevent diverse bla NDM variants from becoming epidemic in the future.