ACS Infectious Diseases最新文献

Salmonella infections remain a priority concern in both developed and developing regions due to antimicrobial resistance and the lack of proper diagnosis. While substantial progress has been made in deciphering the pathogenesis of this ancient pathogen, emerging insights into host–pathogen interactions, particularly those mediated by post-translational modifications (PTMs) orchestrated by bacterial effectors, offer promising avenues for identifying novel drug targets and advancing host-directed therapies. The rise in antimicrobial resistance among priority Salmonella serovars, particularly in the food industry, underscores the urgent need for effective alternatives to antibiotic therapy alongside rapid and accurate diagnostic tools for identifying drug-resistant strains. In this context, phage therapy, along with probiotics, prebiotics, small molecule inhibitors, optimized antimicrobial peptides, and host-directed therapies, has gained attention as a potential therapeutic approach. Simultaneously, diagnosis tools incorporating modern techniques such as high-throughput gene analysis, multiplex ELISAs, microfluidic devices with nanotechnology, computer modeling, and MALDI-TOF pave the way for improved accuracy, high sensitivity, and affordable solutions to a rising concern of misdiagnosis and dependency on culture-based techniques. This review aims to highlight recent discoveries in post-translational modifications by Salmonella effectors affecting host protein localization and function. We also discuss current progress in alternative therapeutic strategies and next-generation diagnostics aimed at combating drug-resistant Salmonella infections.

Berberine (BER), a natural isoquinoline alkaloid, exhibits broad-spectrum antifungal activity, yet its mechanism against Aspergillus fumigatus─a leading cause of invasive fungal infections─remains poorly understood. Here, we aim to unveil the mechanism of BER against the pathogenicity of A. fumigatus through mitochondrial dynamics and related pathways. In vitro assays revealed that berberine treatment triggered mitochondrial fragmentation, resulting in reactive oxygen species (ROS) overaccumulation. Subsequent proteomic analyses identified Hog1-MAPK as the central signaling hub activated by ROS stress. Upon activation, Hog1 localizes to the nucleus. ROS scavenging (N-acetylcysteine (NAC) treatment) abolished BER’s antifungal effects, confirming the ROS-Hog1-cell cycle axis. Crucially, in a murine invasive aspergillosis model, BER reduced the fungal burden in lungs and improved survival rates. Thus, we demonstrate that berberine suppresses A. fumigatus growth by disrupting mitochondrial dynamics, elevating reactive ROS, and activating the Hog1-MAPK signaling cascade, ultimately inducing cell cycle arrest. Our findings unveil a previously unrecognized mechanism linking mitochondrial morphology dysregulation to cell cycle control in fungi and establish BER as a promising therapeutic agent targeting mitochondrial-ROS-Hog1 signaling in A. fumigatus infections.

The global spread of multidrug-resistant bacteria underscores the urgent need for antimicrobial agents with enhanced efficacy and selectivity. Here, we developed antimicrobial peptoids conjugated with zinc-dipicolylamine (ZnDPA) and bivalent Zn₂BPMP motifs for improved bacterial membrane recognition via phosphate binding. The Zn₂BPMP-containing peptoids, 5_Zn₂ and 8_Zn₄, exhibited the highest bacterial selectivity, achieving an increase in selectivity index of >10-fold. Cytotoxicity assays confirmed reduced toxicity against mammalian cells. Mechanistically, Zn₂BPMP conjugation enhanced binding to anionic bacterial surface components, including lipopolysaccharides and lipoteichoic acids, and promoted inner membrane disruption. Furthermore, in a model of multidrug-resistant E. coli-induced sepsis, 5_Zn₂ exhibited potent antimicrobial and anti-inflammatory activity with low in vivo toxicity and therapeutic efficacy. These findings provide insights into the rational design of antimicrobial peptoids and peptidomimetics to selectively target bacteria and highlight their potential as next-generation therapeutics.

Adenylosuccinate lyase (ADSL), encoded by the purB gene, is an essential enzyme in the purine biosynthesis pathway of Mycobacterium tuberculosis (Mtb), making it a promising target for antimicrobial drug development. Here, we report the expression, purification, kinetic characterization, high-throughput screening (HTS), and structural analysis of Mtb ADSL. We developed a highly sensitive and scalable bioluminescent assay using a PPDK-luciferase coupling system to quantify ADSL enzymatic activity via AMP detection. This assay enabled reliable kinetic analysis and successful pilot HTS of a small-molecule library, identifying bithionol and tetraiodothyroacetic acid (Tetrac) as inhibitors of Mtb ADSL. Inhibitory activity was confirmed using an orthogonal fluorescence polarization (FP) assay and further validated using the AMP-Glo luminescence assay. Specificity was evaluated using human ADSL (huADSL) to confirm that the compounds selectively inhibited Mtb ADSL while sparing the human enzyme. Thermal shift and gel-based protein stability assays demonstrated direct binding of bithionol and Tetrac to Mtb ADSL. Furthermore, bithionol and Tetrac displayed antibacterial activity against M. tuberculosis strains H37Ra and H37Rv, with moderate to low cytotoxicity toward human cells. Supplementation with exogenous AMP restored the growth of M. tuberculosis H37Ra inhibited by bithionol and Tetrac, confirming that both compounds act through on-target engagement of Mtb ADSL. The phagocytosis assay demonstrated that the compounds retained intracellular efficacy against M. tuberculosis. Finally, we determined the crystal structures of Mtb ADSL in two apo forms at high resolution (1.78 Å and 2.1 Å), revealing conserved tetrameric architecture with distinct active-site features that differentiate Mtb from human ADSL. Modeling suggested that both compounds bind to an allosteric site adjacent to the active site. These findings provide a framework for structure-guided development of selective ADSL inhibitors as potential antitubercular agents.

Francisella tularensis, the etiological agent of tularemia, is a highly infectious Gram-negative bacterium that poses a significant threat as a potential biowarfare agent. Although antibiotic resistance is uncommon, the potential for widespread antibiotic use following a bioterrorism event, coupled with the risk of resistant strains engineered by malicious actors, has prompted the development of novel medical countermeasures with unique mechanisms of action that are not exploited by current therapies. High-throughput screening has identified a thieno[2,3-d]pyrimidine lead series exhibiting potent activity against F. tularensis. Through systematic structural modifications at various sites on the thienopyrimidine scaffold, the research team has enhanced antibacterial potency, minimized mammalian cell toxicity, and sought to improve aqueous solubility. Mechanism of action studies suggest that the molecular target is NuoD, the NADH quinone oxidoreductase subunit D. Further efforts will be required to improve metabolic stability prior to nomination of a clinical candidate. This research represents an initial step in the development of a narrow-spectrum antibiotic specifically designed to treat tularemia and safeguard public health against biowarfare threats.

Moraxella bovis is a major etiologic agent for infectious bovine keratoconjunctivitis (IBK), commonly known as bovine pink eye. IBK has been a major economic burden to the cattle and dairy industries due to its economic and welfare impacts on affected cattle herds. Antimicrobial treatment of acute IBK infections is often challenging. Vaccine formulations widely used in industry have poor efficacy for the prevention of IBK. Capsular polysaccharides of some bacterial pathogens are important epidemiological markers and are successfully used in vaccines for humans. Currently, there are limited data demonstrating the presence of capsular polysaccharides in M. bovis. In this study, we show by genomic analysis that a broad selection of M. bovis strains obtained from the eyes of cattle harbor a gene cluster for expressing capsular polysaccharides. The isolates potentially express either a chondroitin-like polysaccharide or an α(2–8) polysialic acid. We isolated a polysaccharide from cultures of a well-studied model strain for IBK, the Epp63 strain, structurally identical to capsule α(2–8) polysialic acid of the human pathogens Escherichia coli K1 and Neisseria meningitidis Group B. The gene cluster in M. bovis Epp63 encodes a polysialyltransferase similar to other bacterial polysialyltransferases. Other M. bovis strains analyzed in this study possess a gene homologous to that of bacterial chondroitin synthase. We isolated a capsular polysaccharide from M. bovis genotypes 1 and 2 that has the repeat unit identical to nonsulfated chondroitin. These findings provide a tool for the study of M. bovis IBK pathogenesis that could lead to approaches for better control of the disease.

Staphylococcus aureus poses a global threat to livestock health and public health security, necessitating a novel antibiotic. Pleuromutilin, a natural antibiotic, has served as a promising foundation for developing new antibacterial agents through structural modification. This study aims to evaluate the antibacterial potential, safety, and pharmacokinetic profile of a novel pleuromutilin derivative 2-3 (22-[2-(L-prolylamino)phenylsulfanyl]-22-deoxypleuromutilin). The compound 2–3 exhibited potent antibacterial activity (MIC = 0.25 μg/mL), concentration-dependent bactericidal effects, and prolonged post-antibiotic effects (PAEs). Safety assessments revealed low cytotoxicity (CC₅₀ = 62.63 μg/mL) and no observable hemolytic activity. In vitro metabolic studies indicated species-dependent clearance, primarily mediated by CYP3A4. Pharmacokinetic in rats showed rapid absorption and elimination, with oral and intramuscular bioavailability of 16.03% ± 8.82% and 53.36% ± 12.27%, respectively. Notably, 2–3 demonstrated superior efficacy over tiamulin in a neutropenic murine thigh infection model. Molecular docking revealed a stronger binding free energy between 2–3 and the 50S ribosomal subunit compared to tiamulin. Collectively, these results highlight 2–3 as a promising clinical candidate against S. aureus infections, characterized by enhanced efficacy and a favorable safety profile.

Colorectal cancer, which originates in the epithelial cells of the colon or rectum, is closely associated with dysbiosis of the gut microbiota. Increasing evidence has shown that Fusobacterium nucleatum plays a significant role in colorectal cancer progression by activating inflammatory responses, modulating the tumor microenvironment, and promoting tumor cell proliferation. Antimicrobial peptides targeting Fusobacterium nucleatum have the potential to serve as more effective and less toxic therapeutic agents compared to chemotherapy drugs. In this study, we systematically evaluated the antibacterial activity of Trp-containing peptides, including natural peptides isolated from the skin secretions of the Chinese brown frog (Rana chensinensis) and their derivatives, which exhibit potent antibacterial activity against Fusobacterium nucleatum with minimal cytotoxicity. Mechanistic investigations using membrane permeability assays and membrane potential-sensitive dyes indicated that Trp-containing peptides exert their antimicrobial effects by disrupting the bacterial membrane structure, increasing membrane permeability, and interfering with membrane potential. In a colorectal cancer mouse model infected with Fusobacterium nucleatum, treatment with Trp-containing peptides significantly alleviated tumor-related symptoms, reduced colonic inflammatory cytokine levels, and alleviated colonic tissue damage, as confirmed by histopathological analysis. Importantly, no apparent toxicity or adverse effects were observed during the treatment. These findings indicate that Trp-containing peptides, as lead compounds, not only exhibit potent antibacterial activity but also attenuate Fusobacterium nucleatum associated colorectal cancer progression, providing critical evidence to support the development of innovative therapeutic strategies with combined antimicrobial and antitumor properties.