ACS Infectious Diseases最新文献

Leprosy remains an important neglected tropical disease with about 200,000 new cases detected annually worldwide. Although the disease is highly responsive to treatment, a timely and accurate diagnosis continues to be a critical barrier to disease control. Traditional diagnostic methods, including PCR, bacilloscopy, histopathology, and serology, are hindered by limited sensitivity, procedural complexity, and restricted accessibility in resource-constrained settings. This review summarizes studies from the past decade on biosensor-based strategies for leprosy diagnosis. Biosensor platforms for leprosy include electrochemical, piezoelectric, and optical systems, with recent innovations encompassing immunosensors, biomimetic, and DNA-based approaches, some achieving diagnostic accuracies above 90%. These platforms employ different bioreceptors such as conjugated peptides, DNA probes, and molecularly imprinted polymers. Certain platforms can also differentiate paucibacillary from multibacillary cases, addressing a critical limitation of the current methods. These capabilities highlight the potential of biosensors as powerful tools for point-of-care testing. However, clinical translation is constrained by challenges such as affordability, robustness under field conditions, and the lack of large-scale validation studies. Additional operational barriers, including regulatory approval, supply chain logistics, and user training, must also be addressed. Future progress will depend on multidisciplinary strategies, integrating novel biomarker discovery as recognition elements and exploring detection systems previously used for other mycobacterial and infectious diseases. Large multicenter trials and user-centered design approaches are essential for clinical implementation. By overcoming these challenges, biosensors have the potential to redefine leprosy diagnostics, enabling earlier detection and improved surveillance, and accelerating progress toward global elimination goals.

Visceral leishmaniasis (VL) is a neglected tropical disease affecting humans and dogs, particularly in urban settings. Current therapies are limited by toxicity, lengthy regimens, and emerging drug resistance. No human vaccine is available, and only a few licensed formulations exist for canine use. Here, we evaluated a recombinant Leishmania infantum lipophosphoglycan-3 (rLPG3) antigen formulated with Freund's incomplete adjuvant (FIA) against Leishmania infantum challenge in BALB/c mice. The formulation reduced hepatic parasitism, increased antioxidant enzyme activities (superoxide dismutase, catalase, glutathione S-transferase), and raised total antioxidant capacity and hepatic nitrite/nitrate, while lipid and protein oxidation markers remained unchanged. Vaccination preserved liver architecture, lowered AST/ALT, reduced granuloma number and area, and shifted granuloma maturation toward organized lesions with greater macrophage content; PAS staining indicated higher hepatocyte glycogen in the rLPG3+FIA group. Serologically, rLPG3+FIA increased IgG1 and the IgG1/IgG2a ratio, indicating a Th2-skewed profile concomitant with reduced parasitism. Within the constraints of this model, time point, and the proof-of-concept use of FIA, these convergent readouts support rLPG3 as a promising antigen for further preclinical development─prioritizing licensable veterinary adjuvants to enable translation into canine VL vaccines.

The search for antibiotics is urgent because of the global antibiotic resistance problem. While a variety of strategies are actively sought, interest in antimicrobial peptides persists due to high potency and low chance of resistance development. The establishment of the antimicrobial peptide database laid the foundation for peptide prediction and design. Both artificial intelligence and non-AI approaches have been demonstrated. Since AI remains a black box and does not teach us how to design peptide antibiotics, this study took a database-guided approach. Our peptide design benefited from the recent classification of peptides into hemolytic and nonhemolytic groups in the APD6. Our designed peptides rapidly killed Gram-negative bacteria Escherichia coli and Acinetobacter baumannii, but not Gram-positive methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus subtilis. In addition, our peptide inhibited bacterial attachment, biofilm formation, and disrupted preformed biofilms. Remarkably, YZ200, designed based on the nonhemolytic group, showed no sign of hemolysis even at 400 μM, whereas YZ201, designed based on the hemolytic group, displayed toxicity. Our analysis uncovered a higher hydrophobic ratio for the hemolytic group. Mechanistic studies revealed that the peptide permeabilized and depolarized bacterial membranes. The predicted membrane-bound structure of YZ200 contains a longer amphipathic helix, explaining its higher potency than YZ201. By comparing our experimental results for the designed peptides with AI-predicted activity and toxicity outcomes, it becomes evident that great progress has been made for AI prediction of antimicrobial peptides and such predictions will be improved in the future by including good data as illustrated herein.

Multidrug efflux pumps of the resistance-nodulation-division (RND) superfamily are major contributors to antibiotic resistance in Pseudomonas aeruginosa. Among these, the MexEF-OprN system, when overproduced in clinical isolates, confers resistance to fluoroquinolones, trimethoprim, and chloramphenicol. The inner-membrane RND transporter MexF in this complex exhibits a relatively narrow substrate specificity and the molecular mechanisms underlying this specificity are still unclear. Here, we employed a combination of experimental and computational approaches to dissect the role of a major putative recognition/binding site, the Access pocket, in the substrate specificity of MexF. Mutations at four selected positions D132, P136, G626, and S729 altered resistance profiles and substrate specificity in a residue- and substrate-specific manner. Notably, substitutions at P136 enhanced efflux of most tested antibiotics, among which are 21 fluoroquinolones with different structures. Substitutions in S729, on the other hand, either enhanced or severely impaired MexF activity depending on the substitution. Antibiotic substrates were found to compete with a fluorescent probe for MexF efflux revealing overlapping binding determinants and shared translocation paths within the transporter. Ensemble docking and contact frequency analyses further demonstrated that mutations reshaped ligand binding preferences within the periplasmic cleft, modulating the probability of transition to the Deep pocket and subsequent extrusion. Our results demonstrate that MexF is optimized to trimethoprim-like compounds and single substitutions in key residues can dramatically change the substrate spectrum of this pump. These findings underline the importance of not only static binding contacts between substrates and a polyspecific transporter such as MexF but also spatial occupancy and pathway integrity in determining drug efflux efficiency.

Ocular toxoplasmosis (OT), caused by Toxoplasma gondii, is the leading cause of retinochoroiditis worldwide, with particularly severe cases in Brazil. The treatment used for OT is the combination of cotrimoxazole and corticosteroids. However, this therapy includes prolonged treatment, resistance to circulating strains, and cytotoxic effects for patients. The intensification of the inflammatory response against T. gondii can exacerbate retinal tissue damage. In this study, the HDAC6 inhibitor Tubastatin A was evaluated by intravitreal injection in the murine ocular toxoplasmosis model. Tubastatin A has presented anti-T. gondii activity and an interesting potential for immunoregulation in the approach to eye disease. The inhibition of HDAC6 interferes with the establishment of infection by blocking the recruitment of the host cell cytoskeleton, which is necessary for the active entry of tachyzoites. After 5 days of treatment, Tubastatin A prevented the progression of lesions in the infected retina from the 10th postinfection day. Tubastatin A restored retinal tissue barriers and regulated the HDAC6-Hsp90 pathway, leading to decreased VEGF and HSF1 expression, which may help prevent neovascularization observed in OT patients. A single intravitreal dose of Tubastatin A established an anti-inflammatory microenvironment that supported retinal tissue homeostasis. Tubastatin regulated micro- and macroglial activation, reduced immunolabeling of Iba1 and GFAP (glial fibrillary acidic), and decreased the secretion of IL-12, IL-4, and IL-17A, key cytokines associated with OT pathology. The combination of Tubastatin A with antifolates may be a viable new treatment regimen to protect retinal tissue and prevent blindness in patients.

The soil microbiome, a reservoir of antibiotic-producing bacteria, also harbors resistance determinants encoded within antibiotic biosynthetic gene clusters (BGCs). Studying self-resistance mechanisms, which have evolved in producers to protect against their own toxic metabolites, provides critical insights into the evolution of resistance and the potential vulnerabilities of new antibiotics and can facilitate the production of natural products in heterologous hosts. Here, we describe the self-resistance mechanism to lariocidin (LAR), a recently discovered lasso peptide antibiotic that inhibits the ribosomal machinery and exhibits antibacterial activity against key pathogens. We identified and characterized an N-acetyltransferase enzyme (LrcE) encoded within the LAR BGC that mediates self-resistance in LAR-producing Paenibacillus sp. M2. LrcE is a member of the GCN5-related N-acetyltransferase (GNAT) superfamily and performs site-specific acetylation of LAR at a critical lysine residue. This modification disrupts ribosomal binding, thereby reducing LAR's antibacterial activity. Using in silico modeling, we predicted a conserved acetyl-CoA-binding motif and an LAR-binding region on LrcE. Bioinformatic analysis revealed LrcE homologues in environmental but not clinically relevant pathogens, suggesting a limited risk of horizontal gene transfer and, therefore, supporting the further development of LAR as a next-generation antibiotic.

Emerging evidence has demonstrated the importance of pattern recognition receptors (PRRs), including the nucleotide-binding and oligomerization domain receptor 2 (NOD2), in human health and disease states. NOD2 activation has shown promise with aiding malnutrition recovery, lessening irritable bowel disease (IBD) symptoms, and increasing the efficacy of cancer immunotherapy. Currently, most NOD2 agonists are derivatives or analogs of the endogenous agonist derived from bacterial peptidoglycan, muramyl dipeptide (MDP). These MDP-based agonists can suffer from low oral bioavailability and cause significant adverse side effects. With the goal of broadly improving NOD2 therapeutic interventions, we sought to discover a small molecule capable of activating NOD2 by screening a library of total 1917 FDA approved drugs in a phenotypic assay. We identified a class of compounds, benzimidazoles, that act as NOD2 agonists, with the most potent member of this class being nocodazole. Nocodazole activates NOD2 with nanomolar potency and causes the release of cytokines canonically associated with MDP-induced NOD2 activation, suggesting its potential to elicit similar therapeutic immune effects as MDP and potentially offer improved pharmacological properties.

The increase in the level of antibiotic-resistant Staphylococcus aureus underscores the urgent need for novel therapeutics. Consequently, repurposing clinically approved drugs has emerged as a compelling and time-saving strategy to counteract this escalating antimicrobial crisis. Here, high-throughput screening revealed that GSK2018682, an agonist of sphingosine-1-phosphate receptors S1P1 and S1P5, exhibits potent, broad-spectrum antimicrobial activity, particularly against S. aureus (MIC = 25-50 μM) and E. faecalis (MIC = 12.5-25 μM). GSK2018682 exhibited concentration-dependent bactericidal activity against both MSSA and MRSA, eradicating planktonic S. aureus within 6 h at 4× MIC. At sub-MIC concentrations, GSK2018682 significantly inhibited biofilm formation, and at 4× MIC, it killed the bacterial cells embedded in mature biofilms. Proteomics revealed that GSK2018682 caused global expression perturbations of functional proteins involved in a two-component system, various metabolic pathways, ribosomal functions, and biofilm regulatory factors (e.g., pflB, sarA). Drug Affinity Responsive Target Stability (DARTS) experiments implicated icaB (a PNAG deacetylase) and phospholipid synthase SAOUHSC_01260 as its candidate targets. Furthermore, GSK2018682 could increase membrane permeability, depolarize, and enhance fluidity to disrupt the S. aureus membranes. Exogenous phospholipid supplementation markedly attenuated the antibacterial efficacy of GSK2018682 against S. aureus. Finally, GSK2018682 displayed a strong efficacy in murine models of MRSA infection. In summary, our findings establish GSK2018682 as a promising anti-S. aureus agent with dual antibacterial and antibiofilm activities, acting through interaction with membrane phospholipids to disrupt membrane integrity and offering a strategy against resistant S. aureus infections.

The overuse of conventional antibiotics has enhanced the development of multidrug-resistant bacteria, which necessitates the development of innovative alternatives to combat bacterial infections. Antibacterial photodynamic therapy has emerged as a promising approach for the treatment of bacterial infections by inducing oxidative stress via reactive oxygen species generation. Recently, progress has been made in designing nanomaterial-based photoactive drugs that harness light to generate oxidative stress, effectively destroying bacterial cells upon irradiation. In this study, complex IrL¹ stands out as a photodynamic antimicrobial chemotherapeutic agent. IrL¹ self-assembled in culture media and demonstrated selective activity against Gram-positive Staphylococcus aureus with a minimum inhibitory concentration (MIC) value of 1 μg mL^-1 in the dark and 0.5 μg mL^-1 when irradiated with 390 nm light. It exhibited significant efficacy against methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA), as evidenced by MIC values ranging from 2 μg/mL. Upon irradiation, it induced oxidative stress by producing ¹O₂ and damaged the bacterial cell wall, as demonstrated by SEM and AFM imaging studies, which leads to cell death. Docking studies revealed its targeting of topoisomerase II DNA gyrase (binding energy = -14.33 kcal/mol, k_i = 31.15 pM), essential for bacterial survival. Time-kill assays and drug resistance studies reinforced its antimicrobial potential, and an in vivo evaluation demonstrated its therapeutic promise. Furthermore, the previously reported photodynamic anticancer properties of IrL¹ make it a compelling candidate for integrated therapeutic strategies, especially for cancer patients who are highly vulnerable to bacterial infections due to compromised immunity.

The natural product fidaxomicin (Fdx) is a narrow-spectrum antibiotic clinically prescribed for the treatment of Clostrodioides difficile infections. However, limited cellular uptake reduces its therapeutic potential, particularly against Gram-negative bacteria and mycobacteria. In this study, we investigated Thiol-Mediated Uptake (TMU) to promote the delivery of Fdx into bacterial cells. We synthesized a library of Fdx derivatives bearing cyclic dichalcogenide moieties and evaluated their antimicrobial properties against C. difficile and Mycobacterium tuberculosis, respectively. Remarkably, the synthetic Fdx derivatives retained strong levels of antibacterial activity, and the disulfide-containing analogs outperformed their all-carbon control counterparts in many instances. We then developed a systematic study to investigate the mechanistic impact of the introduced disulfide functionalities by conducting experiments with TMU inhibitors and quantifying intracellular accumulation in Mycobacterium bovis BCG, a model organism for M. tuberculosis, via LC-MS/MS. While complete disentanglement of the factors influencing activity was not feasible, features such as compound stability and lipophilicity were identified as significant contributors. Overall, the superior performance of disulfide analogs suggests that differences in cellular entry or intracellular processing, potentially related to TMU, are involved. This work highlights that TMU remains a viable approach for modulating the uptake of therapeutic agents into bacterial cells.