Microbial pathogenesis最新文献

Viral keratitis & conjunctivitis result in multiple ophthalmic symptoms and even progress to vision loss without timely intervention. Although multitudinous pathogens can cause ocular infections, the regulatory mechanisms underlying virus-host interactions remain incompletely defined. Our clinical and mechanistic investigations identify the co-infection of herpes simplex virus type 1 (HSV-1) and adenovirus as a predominant etiology of viral keratoconjunctivitis in Shenzhen, China (2024). The viral co-infection causes both severe symptoms and inflammations in clinical cases and in vitro. Mechanistically, mTORC2-regulated autophagy plays a pivotal role in viral replication, with mTOR-targeted intervention demonstrating superior antiviral and anti-inflammatory efficacy in corneal epithelial cells. This study elucidates a novel regulatory mechanism of mTORC2 in HSV-1 and adenovirus infection, thereby providing novel targets for the development of drugs against viral keratitis & conjunctivitis.

Vibrio spp. are important bacterial pathogens in aquaculture and can also cause human infections worldwide. Antimicrobial peptides (AMPs) are natural molecules with broad-spectrum antibacterial activity and are therefore considered promising alternatives to conventional antibiotics. In this study, a potential anti-bacterial peptide (GITIQCILPGFVVSKLSKLK, AMP LRSG08) was identified from Penaeus vannamei using ultra-performance liquid chromatography-mass spectrometry and online software. The minimum inhibitory concentrations of AMP LRSG08 against Vibrio parahaemolyticus, Vibrio alginolyticus, and Vibrio vulnificus were 2 μg/mL, 2 μg/mL, and 125 μg/mL, respectively. Furthermore, over 80 % of these bacteria were killed within 2.5 h. The AMP LRSG08 could selectively accumulate on the V. parahaemolyticus cell surface and disrupt the integrity of their cellular membranes, leading to nucleic acid leakage from these cells by specifically targeting the cell membrane. Additionally, AMP LRSG08 exhibited concentration-dependent binding to genomic DNA. In vivo studies further revealed that AMP LRSG08 significantly increased the 72 h survival rate of zebrafish infected with V. parahaemolyticus to 80.0 %. Moreover, LRSG08 exhibited nonhemolytic activity and low cytotoxicity in vitro, indicating a favorable biosafety. The present study not only offers valuable insights for the screening of potential antimicrobial peptides but also establishes a theoretical framework for effective prevention and control strategies against vibriosis in aquatic products.

Burkholderia pseudomallei, the causative agent of melioidosis, is a recognised bioterrorism threat. This microorganism produces a key quorum molecule, 3-Hydroxy-C₁₀ homoserine lactone (3-OH-C₁₀ HSL), which has shown to modulate host immune responses. This study investigated the impact of 3-Hydroxy-C₁₀ HSL on A549 cell line, with a focus on organelle stress and inflammatory responses. Treatment with 3-Hydroxy-C₁₀ HSL (100 μM, 2 h) induces a significant elevation of cytosolic calcium and endoplasmic reticulum (ER) stress, evidenced by BiP upregulation and activation of the PERK-CHOP axis, indicating activation of the unfolded protein response (UPR). Mitochondrial function was compromised, as shown by reduced ATP production, loss of mitochondrial membrane potential (MMP), and elevated mitochondrial ROS generation. Furthermore, lysosomal dysfunction was observed through decreased acridine orange puncta, along with TFEB upregulation and LAMP1 downregulation. Gene expression analysis (10 μM, 6 h) revealed activation of the inflammasome pathway, with increased expression of NLRP3, NLRC4, IL-1β, and IL-18, and enhanced secretion of pro-inflammatory cytokines IL-6, TNF- α, and INF- γ. Overall, 3-Hydroxy-C₁₀ HSL disrupts host cellular homeostasis and induces inflammatory stress, providing novel insights into the molecular mechanisms underlying B. pseudomallei mediated pathogenesis.

Pseudomonas aeruginosa, which is one of the most common opportunistic pathogenic bacteria, poses severe clinical risks for individuals with compromised immune systems, particularly concerning lung infections. Sodium houttuyfonate (SH), an active constituent isolated from Houttuynia cordata, exhibits limited direct antibacterial efficacy in vitro yet demonstrates notable therapeutic effects against bacterial infections in vivo. Nevertheless, the precise mechanisms underlying in vivo antibacterial pharmacological activity of SH remain unclear. Thus, here we investigate the mechanism by which SH alleviates P. aeruginosa-induced acute pulmonary infection, focusing on its influence on macrophage polarization signaling pathways. First, our findings demonstrate that SH effectively alleviated P. aeruginosa-induced acute pulmonary infection in mice, as evidenced by reduced inflammatory infiltration and alveolar damage in vivo. The results indicate that SH significantly modulated the expression of inflammatory mediators (IL-6, TNF-α, IL-1β, IL-10, TGF-β, Arg-1) and key signaling molecules (NF-κB, TLR4, STAT6, p38MAPK). In vitro, 24-h SH treatment decreased NO production and attenuated macrophage phagocytosis, while shifting cytokine profiles from M1 to M2 phenotypes. Immunofluorescence and flow cytometry confirmed decreased CD86 (M1 marker) and increased CD206 (M2 marker) expression, indicating enhanced M2 polarization. Mechanistically, SH suppressed the TLR-4/MyD88/NF-κB pathway while activating the p38MAPK/STAT6 axis. Genetic manipulation further verified that SH regulates TLR-4 and p38MAPK, thereby controlling downstream signaling and inflammatory responses to combat infection. In conclusion, our study suggests that SH promotes macrophage M2 polarization and reduces excessive inflammation in late-stage P. aeruginosa-induced acute pulmonary infection by modulating macrophage polarization through the suppression of pro-inflammatory signaling via the TLR4/MyD88/NF-κB pathway and activation of the p38 MAPK/STAT6 pathway.

Chlamydia trachomatis (C. trachomatis) infection is a prevalent sexually transmitted disease worldwide. Although antibiotics are the standard first-line treatment, the rising incidence of treatment failure highlights the need for alternative therapeutic strategies. Baicalin, a natural flavonoid compound extracted from Scutellaria baicalensis, is known to possess antimicrobial properties. This study aimed to evaluate the anti-chlamydial effects of baicalin. Our results showed that baicalin significantly inhibited the growth of multiple C. trachomatis serovars (A, D, and L2) in HeLa cells, as indicated by reductions in inclusion number and size, as well as decreased cHSP60 level. Moreover, baicalin markedly diminished the production of infectious progeny. Mechanistic investigations suggest that the anti-chlamydial effect of baicalin likely involves direct targeting of elementary bodies to impair their infectivity, rather than interfering with host cell pathways. Furthermore, baicalin exhibited a synergistic inhibitory trend when combined with azithromycin. These findings indicate that baicalin is a promising novel therapeutic candidate for combating C. trachomatis infections.

Candidiasis, caused by yeasts of the Candida genus, is increasingly characterized by a high prevalence of clinical isolates resistant to conventional antifungals, rendering the development of novel therapeutic strategies paramount. Drug repurposing has emerged as a key strategy, utilizing established pharmaceuticals for indications beyond their original design; notably, haloperidol (HAL) has shown promising antimicrobial potential. In this context, the present study evaluates the activity of haloperidol, both as a monotherapy and in combination with conventional antifungals, against fluconazole-susceptible and fluconazole-resistant Candida spp. clinical strains. Furthermore, we investigate the underlying mechanisms of its antifungal action. Experimental approaches included broth microdilution assays to determine the Minimum Inhibitory Concentration (MIC), checkerboard assays for synergistic analysis, and cellular assessments via flow cytometry and fluorescence microscopy. Haloperidol displayed MIC values between 26.67 and 256 μg/mL. Synergistic interactions were identified between haloperidol and the azoles fluconazole and itraconazole, alongside a 2.5 % synergy rate with amphotericin B. Additionally, mechanistic assays confirmed that haloperidol induces programmed cell death (apoptosis) in C. albicans and C. auris strains. The oxidative stress caused by haloperidol altered Ca²⁺ homeostasis, followed by mitochondrial membrane depolarization, reduced ATP production, cytochrome c release into the cytosol and metacaspase activation, reduced viability, phosphatidylserine externalization, promoted fragmentation, damage and methylation of DNA. It also induced expression of genes related to oxidative stress. It reduced mitochondrial depolarization and decreased the reduction of glutathione (GSH), causing morphological alterations. The results suggest the apoptotic pathway as the main antifungal mechanism of haloperidol.

The routine utilisation of prophylactic antibiotics in dairy cows during the dry period has been demonstrated to accelerate the rise of antimicrobial resistance, constituting a significant challenge within the One Health framework. The incorporation of essential oils into nanofibre delivery systems provides a sustainable alternative that has become a pivotal instrument in the field of nanotechnology. This approach integrates the inherent antimicrobial properties of specific compounds with a controlled release mechanism and targeted application. It provides a solution for reducing reliance on antibiotics, and the combination of nanoscience and AI further enhances this method. The utilisation of artificial intelligence has the potential to facilitate precise diagnostics, support personalized treatment plans, and enable predictive health monitoring. Consequently, this can lead to improvements in herd management and a reduction in unnecessary pharmaceutical treatments. These innovations have been demonstrated to have a number of benefits, including the promotion of animal health, food security and the strengthening of agricultural systems. In accordance with the EU Green Deal and global sustainability goals, the utilisation of nanofibre-based phytotherapeutics has been demonstrated to assist in the reduction of carbon emissions, the minimisation of drug residues, and the safeguarding of public health. The ethical development of these technologies necessitates a One Health perspective, underpinned by scalable manufacturing techniques, comprehensive environmental impact assessments, and harmonised regulatory frameworks. The integration of nanotechnology, phytotherapy and artificial intelligence has the potential to transform veterinary diagnostics and treatments, thereby establishing sustainable dairy farming as a paradigm for climate-resilient agricultural innovation.

Drug-resistant Klebsiella pneumoniae (K. pneumoniae) represents a formidable clinical challenge. Targeting its quorum sensing (QS) system has emerged as a promising anti-virulence strategy to combat antibiotic resistance. In this study, eighteen pentacyclic triterpenes (PTs) were screened for their in vitro activity against K. pneumoniae. Among them, madecassic acid (PT-5) exhibited a negligible bactericidal effect but significantly suppressed key virulence traits in a highly virulent, multidrug-resistant K. pneumoniae strain (KP31). These suppressed traits included biofilm formation, AI-2 production, capsular polysaccharide synthesis, and swarming motility, identifying PT-5 as a potent quorum sensing inhibitor with anti-virulence properties. Moreover, PT-5 demonstrated a synergistic effect at a subinhibitory concentration (32 μg/mL) when combined with conventional antibiotics, enhancing the bactericidal activity of kanamycin by 31 %, streptomycin by 29 %, azithromycin by 24 %, and chloramphenicol by 24 %. In a Galleria mellonella larval infection model, PT-5 in combination with kanamycin markedly boosted larval survival to 60 %, compared with 20 % for kanamycin monotherapy. Quantitative PCR analysis further revealed that PT-5 significantly downregulated the expression of key QS-related genes (luxS, sdiA, lsrK) and major virulence-associated genes (wbbM, wzm, pgaA, mrkA) in KP31. In summary, PT-5 acts as an effective QS inhibitor that suppresses virulence and enhances antibiotic efficacy, representing a promising combinational therapy against drug-resistant K. pneumoniae.

Listeria monocytogenes is a major foodborne pathogen responsible for listeriosis, a severe disease with high fatality rates that typically requires antimicrobial therapy. This study aimed to characterize antimicrobial resistance and the presence of hypervirulence-associated LIPI-3 and LIPI-4 markers in L. monocytogenes from foods and food-processing environments in southern Brazil, and to evaluate the genetic relatedness of multidrug-resistant (MDR) isolates using Pulsed-Field Gel Electrophoresis (PFGE). Among 82 isolates, resistance was observed to clindamycin (CLI, 48.7%), meropenem (MER, 29.3%), sulfamethoxazole/trimethoprim (SUT, 29.3%), rifampicin (RIF, 14.6%), erythromycin (ERY, 10.9%), tetracycline (TET, 8.5%), streptomycin (STR, 7.3%), and amikacin (AMK, 4.9%). All tetracycline-resistant isolates carried the tetM gene (7/7), and 85.7% (6/7) also carried the tetL gene. Among erythromycin-resistant isolates, the ermB gene was detected in 11.1% (1/9). Fifteen isolates (18.3%) showed multidrug resistance, with the ERY-CLI-RIF-MER-SUT-TET profile being the most prevalent. Regarding virulence, all 15 MDR isolates harbored LIPI-1 and LIPI-2 genes, whereas 60% of the isolates carried at least one of the hypervirulence-associated pathogenicity islands, LIPI-3 or LIPI-4, or both. MDR L. monocytogenes showed distinct PFGE patterns (n=15), indicating high genetic diversity, including among hypervirulent isolates. This study demonstrates the occurrence of L. monocytogenes isolates in foods and food-processing environments in southern Brazil that are resistant to clinically relevant antimicrobials, including multidrug resistance, and that also exhibit hypervirulent genotypes. The coexistence of antimicrobial resistance and hypervirulence in L. monocytogenes underscores the urgent need for continuous monitoring and control strategies to mitigate public health risks.

Escherichia coli (E. coli) is one of the most common commensal bacteria in the intestinal tract of humans and animals. It serves as a major reservoir of antimicrobial resistance genes and may facilitate their horizontal transfer among different hosts. In this study, 212 fecal samples were collected from mink across four northern provinces of China, a total of 110 E. coli isolates were recovered (isolation rate, 51.89 %). Preliminary antimicrobial screening was conducted using four clinically critical antibiotics, including ceftazidime (CAZ), polymyxin B (PMB), meropenem (MEM), and tigecycline (TGC), with CAZ resistance being the most prevalent, followed by PMB, MEM, and TGC. Further antimicrobial susceptibility testing against ten commonly used antibiotics in 49 representative isolates revealed universal multidrug resistance (MDR), including 100 % resistance to imipenem, tetracycline, enrofloxacin, florfenicol, and sulfamethoxazole. Genetic screening identified multiple resistance genes such as aac(3')-IIa, bla_CTX-M, tet(A), and mcr-1. Conjugation assays demonstrated that CAZ resistance was the most transferable. Virulence profiling revealed a low prevalence of classical pathogenic virulence factors, with only six virulence gene types detected, consistent with the results of Galleria mellonella infection assays. Whole-genome sequencing of 41 representative isolates revealed 87 unique antibiotic resistance genes (ARGs) types spanning 14 antibiotic classes including alinically important determinants such as bla_CTX-M, tet, and mcr, and 71 unique virulence genes assigned to 65 functions. Metagenomic analysis further identified diverse ARGs within the mink gut microbiota, with 21 shared between whole-genome and metagenomic sequencing. Correlation analysis suggested co-occurrence patterns among ARGs, virulence factor genes (VFGs), and mobile genetic elements (MGEs), particularly between ARGs and MGEs. Overall, mink-derived E. coli exhibited extensive MDR but limited classical pathogenic virulence, and the mink gut microbiota may represent an important reservoir and transmission hub for resistance genes in intensive farming ecosystems.