Microbial pathogenesis最新文献

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.

Chronic bronchitis (CB) is a complex respiratory disease characterized by a persistent cough, dyspnea, and excessive sputum production. Flos Farfarae (FF), derived from the dried flower buds of Tussilago farfara L. (Asteraceae), has a long history of use in Traditional Chinese Medicine (TCM) for treating respiratory ailments. In our study, FF treatment significantly reduced serum interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-α) in the CB rats, and hematoxylin and eosin (HE) staining of lung and colon tissues also indicated obvious reduction in inflammatory infiltrates. Additionally, we found that FF treatment markedly decreased the abundance of the lung bacterium Pseudomonas and the gut bacterium Roseburia. Bugbase analysis showed that FF was able to reduce the increased potentially pathogenic bacteria in the lung and gut microbiota of CB rats. Serum pseudo-targeted metabolomic analysis showed that FF significantly modulated 31 differential serum metabolites, including palmitoleic acid and indoxyl sulfate. Furthermore, correlation-based ensemble network analysis revealed that interactions between lung and gut microbiota were significantly increased in the CB rats. Similarly, interactions between lung microbiota and serum metabolites, as well as between gut microbiota and serum metabolites, were significantly enhanced. However, FF treatment significantly reduced these interactions. FF treatment not only alleviates the inflammatory state of rats with chronic bronchitis by modulating specific lung and gut microbiota and serum metabolites, but also may restore gut and lung microbial homeostasis by decreasing serum metabolite-mediated interactions between the lung and gut microbiota, thereby resulting in therapeutic effects in rats with CB. We systematically evaluated the efficacy of the traditional Chinese medicine FF in CB from the innovative perspective of serum metabolite-mediated interactions between lung and gut microbiota for the first time.

Avian pathogenic Escherichia coli (APEC) cause significant economic losses in the poultry industry, further exacerbated by the growing number of multi-drug resistance pathogens that make treating infections more difficult. To combat this, the study presents two novel Schitoviridae phages (PBM-2 and PBM-3) and a novel Straboviridae phage (PBM-1) that show significant and highly specific lytic activity against APEC strains. Moreover, the phages show significant lytic activity at MOI as low as 0.1 and show substantial thermal (4-45 °C) and acidic tolerance (pH 3-7). The PBM phages also show suitable growth parameters, with high adsorption rates (9-15 min), relatively short latent periods (20-25 min), and a good burst size (∼100 per cell). The genome sizes for the PBM phages are around 121 kb for PBM-1 and 72 kb for PBM-2 and PBM-3, with 194, 84 and 83 predicted genes, respectively. Comparative genomic analysis revealed a high sequence similarity between PBM-2 and PBM-3. Further analysis showed a high degree of relatedness of PBM-1 with Escherichia phage EPIMAM01 and Escherichia phage HP3, as well as PBM-2 and PBM-3 with Escherichia phage UE-S5b, Enterobacteria phage Bp4. Furthermore, no genes associated with antibiotic resistance, lysogeny, or known virulence factors were detected, supporting their suitability for therapeutic use. The isolation and characterization of these novel phages presents an opportunity to develop effective phage therapies against avian colibacillosis.

Aeromonas dhakensis is an emerging pathogen responsible for infections in humans, livestock, and aquatic species, posing a threat to public health and aquaculture. This study investigates the roles of two critical genes, arnA and ugd, which are involved in polymyxin resistance, by creating single (ΔarnA) and double (ΔugdΔarnA) deletion mutants in A. dhakensis. The mutants showed impaired motility, increased sensitivity to polymyxin, and altered biofilm formation. Virulence was reduced in zebrafish models, with ΔarnA exhibiting a 2.03-fold increase in median lethal dose (LD₅₀), and ΔugdΔarnA showing a 7.13-fold increase. Immunization with these mutants provided significant protection, with survival rates of 65 % and 40 %, respectively, after challenge with the wild-type isolate, compared to the control group. These results underscore the critical roles of arnA and ugd in polymyxin resistance and virulence, highlighting their potential as targets for vaccine development in aquaculture disease control.

Objectives: The purpose of this study was to determine significant clinical risk factors for sputum smear-positivity in Chronic Obstructive Pulmonary Disease (COPD) patients who were also diagnosed with active tuberculosis.

Methods: A total of 776 patients diagnosed with COPD combined with active tuberculosis at West China Hospital of Sichuan University were retrospectively included. Of these, 527 were sputum smear-negative and 249 were sputum smear-positive at first diagnosis. Baseline data, routine blood and biochemical indices were compared between the two groups. Logistic regression was used to investigate the risk factors for sputum smear-positivity in COPD patients with active tuberculosis.

Results: Compared with those in the sputum smear-negative group, patients in the sputum smear-positive group had lower Body Mass Index (BMI), and were more likely to have a history of significant alcohol consumption (p < 0.05). Patients with chronic kidney disease and cardiovascular disease had lower risk of sputum smear positivity (p < 0.05). The hemoglobin concentration, lymphocyte count and albumin levels were significantly lower and the neutrophil, monocyte and platelet counts, blood glucose levels and erythrocyte sedimentation rate were higher in the sputum smear-positive group than those in the sputum smear-negative group (p < 0.05). Multivariate logistic regression analysis showed that low BMI (OR:0.86; 95 %CI:0.79, 0.94;p = 0.001), alcohol consumption (OR:2.13; 95 %CI:1.15,3.93;p = 0.016), low albumin (OR:0.91; 95 %CI:0.85, 0.97;p = 0.003), and elevated neutrophils (OR:3.44; 95 %CI:1.23, 9.28;p = 0.019) were significant risk factors for sputum smear positivity in patients with COPD combined with active tuberculosis.

Conclusion: In patients with COPD and active tuberculosis, alcohol consumption history, increased neutrophil count, low BMI and low serum albumin concentration are significant risk factors for sputum smear positivity at initial diagnosis. These risk factors should prompt clinicians to consider sputum examination. Respiratory isolation may be needed based on individual assessment.

The hygiene hypothesis proposes that infections acquired through the fecal-oral route or contaminated food, such as Toxoplasma gondii, may protect against IgE-mediated allergic disorders. Epstein-Barr virus (EBV) has been negatively associated with atopy, while Anisakis simplex and Helicobacter pylori are associated with acute and chronic urticaria, respectively. This study aimed to explore the impact of coinfection status on anisakiasis-associated phenotypes. A total of 112 human subjects were categorized by Anisakis sensitization status and clinical phenotypes: 25 with gastroallergic anisakiasis (GAA), 64 with chronic urticaria (CU; of these, 32 sensitized to A. simplex [CU+]), and 23 controls without urticaria. Serum IgE against A. simplex and IgG against T. gondii, H. pylori, and EBV were measured to assess exposure and coinfection patterns. Serum cytokine levels of IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, IL-17A, and TGF-β were quantified using flow cytometry. T. gondii coinfection was significantly more prevalent in A. simplex-seropositive subjects (AK+) (95.3 %), whereas H. pylori prevalence was higher in CU patients (55.9 %). All CU+ patients showed coinfection with H. pylori and triple coinfection (A. simplex/T. gondii/H. pylori) was more frequent in CU+ than CU-. Inverse correlations occurred between anti-T. gondii IgG and IL-2, and anti-Anisakis IgE and IFN-γ; positive correlations with anti-H. pylori IgG and IL-17A, and anti-EBV IgG and IL-6. T. gondii infection is associated with anti-A. simplex IgE regardless of CU. H. pylori infection is linked to CU independently of A. simplex sensitization. Studied coinfections modulate immune responses and alter cytokine profiles underscoring complex immunoregulatory mechanisms of Anisakis allergy.