Overall mutational scanning unveils the essential active residues for the mechanistic action of MCR-1.

Polymyxins, including colistin and polymyxin B, serve as crucial last-resort antibiotics for managing infections caused by carbapenem-resistant Enterobacterales (CRE). However, the rapid spread of the mobilized colistin resistance gene (mcr-1) challenged the efficacy of treatment by polymyxins. The mcr-1 gene encoded a transmembrane phosphoethanolamine (PEA) transferase enzyme, MCR-1.

Repurposing cetylpyridinium chloride and domiphen bromide as phosphoethanolamine transferase inhibitor to combat colistin-resistant Enterobacterales.

The emergence of plasmid-encoded colistin resistance mechanisms, MCR-1, a phosphoethanolamine transferase, rendered colistin ineffective as last resort antibiotic against severe infections caused by clinical Gram-negative bacterial pathogens. Through screening FDA-approved drug library, we identified two structurally similar compounds, namely cetylpyridinium chloride (CET) and domiphen bromide (DOM), which potentiated colistin activity in both colistin-resistant and susceptible Enterobacterales. These compounds were found to insert their long carbon chain to a hydrophobic pocket of bacterial phosphoethanolamine transferases including MCR-1, competitively blocking the binding of lipid A tail for substrate recognition and modification, resulting in the increase of bacterial sensitivity to colistin.

Integrating metagenomic and isolation strategies revealed high contamination of pathogenies and resistome in market shrimps.

This study employs a comprehensive approach combining metagenomic analysis and bacterial isolation to elucidate the microbial composition, antibiotic resistance genes (ARGs), and virulence factors (VFGs) present in shrimps from market and supermarket. Metagenomic analysis of shrimps revealed a dominance of Proteobacteria and Bacteroidetes with Firmicutes notably enriched in some samples. On the other hand, the dominant bacteria isolated included Citrobacter portucalensis, Escherichia coli, Salmonella enterica, Vibrio species and Klebsiella pneumonaie.

Comprehensive genomic and plasmid characterization of multidrug-resistant bacterial strains by R10.4.1 nanopore sequencing.

The escalating prevalence of multidrug-resistant (MDR) bacteria pose a significant public health threat. Understanding the genomic features and deciphering the antibiotic resistance profiles of these pathogens is crucial for development of effective surveillance and treatment strategies. In this study, we employed the R10.

Recovery and genetic characterization of clinically-relevant ST2 carbapenem-resistant Acinetobacter baumannii isolates from untreated hospital sewage in Zhejiang Province, China.

The global transmission of carbapenem-resistant Acinetobacter baumannii (CRAB) poses a significant and grave threat to human health. To investigate the potential relationship between hospital sewage and the transmission of CRAB within healthcare facilities, isolates of Acinetobacter spp. obtained from untreated hospital sewage samples were subjected to antimicrobial susceptibility tests, genome sequencing, and bioinformatic and phylogenetic tree analysis, and that data were matched with those of the clinical isolates.

Deciphering mechanisms of gene transmission between human and animals: a genomics study of bacterial isolates from various sources in China, 2015 to 2017.

BackgroundIn China, the gene has been recovered from human bacterial isolates since 2011. After 2014, detections of this gene in animal and food bacterial isolates have increasingly been reported.AimWe aimed to understand how -bearing bacteria could spread between humans, animals, and animal-derived food.

Epidemiological and Genetic Characteristics of Clinical Carbapenem-Resistant Strains in Guangdong Province, China.

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a bacterial pathogen that may cause serious drug-resistant infections that are potentially fatal. To investigate the genetic characteristics of these organisms, we tested 416 P. aeruginosa strains recovered from 12 types of clinical samples collected in 29 different hospital wards in 10 hospitals in Guangdong Province, China, from 2017 to 2020.

Genetic and drug susceptibility profiles of mcr-1-bearing foodborne Salmonella strains collected in Shenzhen, China during the period 2014-2017.

Colistin resistance mediated by mcr-1-bearing plasmids poses a new challenge to treatment of Salmonella infections. To probe the scale of the problem that colistin resistance mediated by mcr-1 plasmids among Salmonella, the prevalence of mcr-1 in foodborne Salmonella recovered from 2014 to 2017 in Shenzhen, China and genetic profile of mcr-1 positive isolates were investigated. All mcr-1 positives Salmonella strains were collected from food products, characterized by PCR and MALDI-TOF, and subjected to antimicrobial susceptibility testing, whole-genome sequencing, bioinformatics analysis, and conjugation.

Genomic insights into the emergence and spread of NDM-1-producing Vibrio spp. isolates in China.

Background: Carbapenemase-producing Vibrio spp., which exhibit an XDR phenotype, have become increasingly prevalent and pose a severe threat to public health.

Objectives: To investigate the genetic characteristics of NDM-1-producing Vibrio spp.

Epidemiological and genetic characteristics of clinical carbapenem-resistant strains collected countrywide from hospital intensive care units (ICUs) in China.

is one of the key Gram-negative pathogens that can cause serious nosocomial infections. In China, a large proportion of clinical strains are multidrug resistant, among which strains resistant to carbapenems are particularly worrisome, as infections caused by such strains may limit the choice of existing antibiotics. We conducted a nationwide and genome-based surveillance on the prevalence and antibiotic susceptibility profile of carbapenem-resistant (CRAB) strains collected from intensive care units (ICUs) in hospitals in different provinces and investigated the routes of transmission and mechanism of resistance by whole-genome sequencing and phylogenetic analysis.

Otilonium bromide boosts antimicrobial activities of colistin against Gram-negative pathogens and their persisters.

Colistin is the last-line antibiotic against Gram-negative pathogens. Here we identify an FDA-approved drug, Otilonium bromide (Ob), which restores the activity of colistin against colistin-resistant Gram-negative bacteria in vitro and in a mouse infection model. Ob also reduces the colistin dosage required for effective treatment of infections caused by colistin-susceptible bacteria, thereby reducing the toxicity of the drug regimen.

Functional and phylogenetic analysis of TetX variants to design a new classification system.

Recently, many TetX variants such as Tet(X3~14) were reported to confer resistance to tigecycline which is a last-resort antibiotic used to treat infections caused by multidrug-resistant bacteria. In this study, we identified essential residues including 329, 339, 340, 350, and 351 in TetX variants that mediated the evolution of the tigecycline-inactive Tet(X2) enzyme to the active forms of Tet(X3) and Tet(X4). Based on their amino acid sequences and functional features, we classified TetX variants into TetX-A class, TetX-B class and TetX-C class.

High-Resolution Metagenomics of Human Gut Microbiota Generated by Nanopore and Illumina Hybrid Metagenome Assembly.

Metagenome assembly is a core yet methodologically challenging step for taxonomic classification and functional annotation of a microbiome. This study aims to generate the high-resolution human gut metagenome using both Illumina and Nanopore platforms. Assembly was achieved using four assemblers, including Flye (Nanopore), metaSPAdes (Illumina), hybridSPAdes (Illumina and Nanopore), and OPERA-MS (Illumina and Nanopore).

A Siderophore-Encoding Plasmid Encodes High-Level Virulence in Escherichia coli.

A plasmid that harbored the virulence factors highly like those of the virulence plasmid commonly found in clinical hypervirulent Klebsiella pneumoniae strains was detected in a foodborne Escherichia coli strain EC1108 and designated p1108-IncFIB. This virulent-like plasmid was found to be common in E. coli from various sources.

Unveiling the evolution routes of TEM-type extended-spectrum β-lactamases.

The TEM-1 β-lactamase can only cleave penicillin and the first-generation cephalosporins but it has evolved to become active against second-, third- and fourth-generation drugs. Through sequence analysis of natural TEM variants and those created by mutagenesis experiments, we described two distinct evolution routes of TEM-1 that has generated over 220 enzyme variants. One began with the GlySer alteration and the other originated with the ArgSer substitution.

Structural and mechanistic basis of the high catalytic activity of monooxygenase Tet(X4) on tigecycline.

Background: Tigecycline is a tetracycline derivative that constitutes one of the last-resort antibiotics used clinically to treat infections caused by both multiple drug-resistant (MDR) Gram-negative and Gram-positive bacteria. Resistance to this drug is often caused by chromosome-encoding mechanisms including over-expression of efflux pumps and ribosome protection. However, a number of variants of the flavin adenine dinucleotide (FAD)-dependent monooxygenase TetX, such as Tet(X4), emerged in recent years as conferring resistance to tigecycline in strains of Enterobacteriaceae, Acinetobacter sp.

Membrane Transporters of the Major Facilitator Superfamily Are Essential for Long-Term Maintenance of Phenotypic Tolerance to Multiple Antibiotics in E. coli.

Antibiotic tolerance is not only the key underlying the cause of recurrent and chronic bacterial infections but it is also a factor linked to exacerbation of diseases, such as tuberculosis, cystic fibrosis-associated lung infection, and candidiasis. This phenomenon was previously attributed to a switch to physiological dormancy in a bacterial subpopulation triggered by environmental signals. However, we recently showed that expression of phenotypic antibiotic tolerance during nutrient starvation is highly dependent on robust production of proteins that actively maintain the bacterial transmembrane proton motive force (PMF), even under a nutrient-deficient environment.

Econazole as adjuvant to conventional antibiotics is able to eradicate starvation-induced tolerant bacteria by causing proton motive force dissipation.

Objectives: Bacterial antibiotic tolerance is responsible for the recalcitrance of chronic infections. This study aims to investigate a potential drug that can effectively kill antibiotic-tolerant bacteria and evaluate the ability of this drug on the eradication of tolerant cells both in vitro and in vivo.

Methods: The in vitro effect of econazole on eradicating starvation-induced tolerant bacterial populations was studied by testing the amount of survival bacteria in the presence of econazole combining conventional antibiotics.

Active maintenance of proton motive force mediates starvation-induced bacterial antibiotic tolerance in Escherichia coli.

Recent evidence suggests that metabolic shutdown alone does not fully explain how bacteria exhibit phenotypic antibiotic tolerance. In an attempt to investigate the range of starvation-induced physiological responses underlying tolerance development, we found that active maintenance of the transmembrane proton motive force (PMF) is essential for prolonged expression of antibiotic tolerance in bacteria. Eradication of tolerant sub-population could be achieved by disruption of PMF using the ionophore CCCP, or through suppression of PMF maintenance mechanisms by simultaneous inhibition of the phage shock protein (Psp) response and electron transport chain (ETC) complex activities.

The hypermucoviscosity of hypervirulent confers the ability to evade neutrophil-mediated phagocytosis.

Hypervirulent (HvKP), which causes highly fatal infections, is a new threat to human health. In an attempt to investigate the underlying mechanisms of resistance to neutrophil-mediated killing and hence expression of high-level virulence by HvKP, we tested the binding affinity of HvKP strains to various types of human cells. Our data showed that HvKP exhibited weaker binding to both lung epithelial cells, intestinal Caco-2 cells and macrophages when compared to the classic, non-hypervirulent strains (cKP).

Evolution of Ciprofloxacin Resistance-Encoding Genetic Elements in .

The incidence of ciprofloxacin resistance in has increased dramatically in the past decade. To track the evolutionary trend of ciprofloxacin resistance-encoding genetic elements during this period, we surveyed the prevalence of in food products in Shenzhen, China, during the period of 2012 to 2017 and performed whole-genome sequencing and genetic analysis of 566 ciprofloxacin-resistant clinical strains collected during this survey. We observed that target gene mutations have become much less common, with single mutation currently detectable in serovar Typhimurium only.

-Acetyl-D-Glucosamine Acts as Adjuvant that Re-Sensitizes Starvation-Induced Antibiotic-Tolerant Population of to β-Lactam.

Bacterial tolerance to antibiotics causes reduction in efficacy in antimicrobial treatment of chronic and recurrent infections. Nutrient availability is one major factor that determines the degree of phenotypic antibiotic tolerance. In an attempt to test if specific nutrients can reverse phenotypic tolerance, we identified -acetyl-D-glucosamine (GlcNAc) as a potent tolerance-suppressing agent and showed that it could strongly re-sensitize a tolerant population of to ampicillin.