ACS Infectious Diseases最新文献

The rise of multidrug-resistant (MDR) Neisseria gonorrhoeae is a growing health concern. New treatments are urgently needed as resistance to last-line antibiotics increases. The zinc ionophore, PBT2, has previously been shown to facilitate zinc uptake in bacteria and restore susceptibility to existing antibiotics in combination therapies. In contrast, we demonstrate that PBT2 alone is sufficient to inhibit the growth of N. gonorrhoeae. Guided by this finding, we synthesized a series of 8-hydroxyquinoline-based new chemical entities, herein termed a “ionophoroantibiotics (IP-antibiotics).” These compounds displayed potent activity against MDR N. gonorrhoeae, with several exhibiting greater efficacy than PBT2. Proteomic profiling studies suggested IP-antibiotics disrupt metal and phosphate metabolism in N. gonorrhoeae, upregulating iron transport and downregulating phosphate pathways. PBT2 broadly affects metal and metabolic proteins, whereas the new compounds act more selectively. This distinct mode of action circumvents established resistance mechanisms and targets key bacterial vulnerabilities. Collectively, these findings identify IP-antibiotics as a promising new class of antibiotics for the treatment of MDR N. gonorrhoeae.

The limitations of the current standard therapy for pulmonary diseases caused by Mycobacterium avium complex (MAC) underscore the urgent need for novel therapeutic agents. Among potential candidates, thiopeptide antibiotics have attracted attention due to their antibacterial activity but their poor solubility has limited clinical application. In this study, we developed AJ-099, a thiopeptide derivative with improved solubility and enhanced antibacterial potency. The in vitro antibacterial activity of AJ-099 was confirmed across macrolide-susceptible and- resistant clinical isolates, with minimum inhibitory concentration values consistently falling within the range of ≤0.125–0.5 μg/mL. In addition, AJ-099 exhibited a marked growth inhibition against both macrolide-susceptible and -resistant MAC clinical isolates in macrophages. Importantly, AJ-099 displayed synergistic effects in combination with clarithromycin (CLR), a macrolide drug, which resulted in significantly greater reductions in intracellular MAC burden compared to either agent alone. The synergistic effect was consistently observed in vivo, where the AJ-099 and CLR combination achieved superior bacterial clearance and reduced lung inflammation to the current standard therapy consisting of CLR, ethambutol, and rifampicin. Collectively, these results highlight that AJ-099 in combination with macrolides is a promising candidate for treating MAC pulmonary infections. Moreover, its potent activity against macrolide-resistant MAC strains suggests it may offer an effective therapeutic option for refractory MAC pulmonary infections.

Vancomycin-resistant enterococci are multidrug-resistant bacteria that as of 2021 continue to pervade the U.S. healthcare system as the second-most prevalent source of healthcare-acquired infections behind Escherichia coli. Given the limited treatment options for vancomycin-resistant enterococci and growing concerns about antibiotic-induced gut microbiome dysbiosis, there is an urgent need for narrow-spectrum antibiotics that can selectively target vancomycin-resistant enterococci while preserving the integrity of the gut microbiome. Previous studies have demonstrated the in vivo potential of orally dosed acetazolamide-based compounds to reduce vancomycin-resistant enterococci bioburden in the gastrointestinal tract and internal organs of mice. However, while it is hypothesized that these molecules inhibit bacterial carbonic anhydrases, the exact target of the acetazolamide scaffold in vancomycin-resistant enterococci has remained unconfirmed. Additionally, the impact of the scaffold on in vivo gut microbiome diversity remains uncharacterized. The work herein reports the chemoproteomic identification of α-carbonic anhydrase as the primary target of the acetazolamide scaffold in E. faecium and presents its uniqueness as a narrow-spectrum antibiotic target that can be exploited by CAI0019, a lead acetazolamide derivative with in vivo efficacy, while sparing gut microbiome diversity in mice. This work presents compelling data that not only confirm α-carbonic anhydrase as an antibiotic target in Enterococcus but also demonstrate that narrow-spectrum in vivo antienterococcal efficacy can be achieved through targeting α-carbonic anhydrase such that gut commensal microbiota remain unimpacted.

Multidrug-resistant (MDR) Acinetobacter baumannii presents a critical therapeutic challenge due to its extensive antibiotic resistance and the paucity of effective alternatives. This study evaluated whether minimal PEGylation could enhance the pharmacokinetic performance, immune compatibility, and antibacterial efficacy of the lytic phage vB_AbaSt_W16 in an immunocompetent murine model of systemic infection. The phage vB_AbaSt_W16 was conjugated with methoxy polyethylene glycol succinimidyl ester (mPEG-S-NHS, MW 5000) at a low concentration (4.2 pM), experimentally defined as the minimal PEGylation level. PEGylation efficiency, infectivity, adsorption, and replication kinetics were characterized in vitro, and serum and intracellular stability were assessed using mouse or human serum and RAW 264.7 macrophages. In vivo pharmacokinetics and therapeutic efficacy were examined in BALB/c mice challenged intraperitoneally with MDR A. baumannii KBN10P02782, while immune responses were profiled by cytokine quantification and antiphage IgG enzyme-linked immunosorbent assay (ELISA). PEGylated vB_AbaSt_W16 retained infectivity and adsorption capacity while markedly improving pharmacokinetics, showing a 2.7- to 3.7-fold increase in half-life, a >200-fold reduction in systemic clearance, and a >1000-fold increase in the area under the plasma concentration (AUC_0-t) relative to the wild-type (WT) phage. The PEGylated phage remained detectable for up to 96 h and achieved complete bacterial clearance within 72–96 h. Immune profiling revealed attenuated proinflammatory cytokine responses and reduced antiphage IgG titers, indicating diminished Th1/Th2 activation. These effects were phage-specific, as the structurally related vB_AbaSi_W9 (a siphovirus) exhibited no comparable improvements following PEGylation. Collectively, minimal PEGylation of vB_AbaSt_W16 enhanced circulation time, immune evasion, and infection control without impairing infectivity. This strategy offers a phage-compatible, structure-informed approach to overcoming key translational barriers in systemic phage therapy and establishes a quantitative framework for optimizing PEGylation in future bacteriophage therapeutics.

Enzyme-mediated resistance is among the main strategies that bacteria use to evade antibiotic action. S-Adenosylmethionine-dependent erythromycin resistance methyltransferases catalyze the methylation of 23S rRNA in bacteria, causing resistance to macrolides, lincosamides, and streptogramin type-B antibiotics. Given the diversity and number of identified variants of these enzymes, it is vital to devise ways of inhibiting their activity to rescue affected antibiotics. Here, we use computer-aided solvent mapping and virtual screening techniques to identify inhibitors of Erms displaying promising adjuvant properties. We further demonstrate that an E. coli model expressing a recombinant S. aureus ErmC (SaErmC) variant causes substantial resistance to representative macrolide and lincosamide antibiotics. Assessment of test compounds using this resistance model revealed candidates that displayed promising adjuvant activity when combined with erythromycin or clindamycin. Antibiotic combinations with a principal candidate oxadiazole, JNAL-016, completely blocked SaErmC-mediated resistance against erythromycin, resulting in an antibiotic-sensitive phenotype in broth microdilution screening assays. This compound also suppressed ErmC activity, allowing erythromycin to regain its bactericidal properties when assessed in actively growing cultures using time-kill assays. JNAL-016 displayed a noncompetitive mode of inhibition against SaErmC activity in vitro and bound the purified enzyme with high affinity (K_d = 1.8 ± 0.7 μM) based on microscale thermophoresis data. Competition experiments suggested that JNAL-016 competes with SAM for its binding pocket on the enzyme, and this compound exhibited no toxicity against human embryonic kidney cells. These findings establish a practical strategy for targeting Erm-mediated resistance, which could lead to a viable adjuvant-based therapy against bacterial pathogens that weaponize variants of this class of methyltransferases.

Multidrug-resistant pulmonary infections pose significant therapeutic challenges as treatment options continue to dwindle in the face of rising antimicrobial resistance. Similar challenges arise in the management of wound infections such as those resulting from burn and blast injuries, where resistant pathogens severely limit treatment options. These wounds are further complicated by high microbial loads that exacerbate tissue damage, delay healing, and increase the risk of systemic infection. The escalating threat of antimicrobial resistance highlights the urgent need for innovative therapeutic strategies. This study evaluates the therapeutic potential of a novel topical formulation, azithromycin-bicarbonate (AZM-BIC), for addressing drug-resistant infections in both pulmonary and wound settings. Using murine models of infection in bicarbonate-depleted environments, including lung, blast injury, and burn wound models, topical administration of AZM-BIC enabled the localized delivery of therapeutic concentrations of bicarbonate. In the pulmonary model, AZM-BIC significantly reduced the bacterial burden. In vitro and ex vivo studies revealed AZM-BIC’s ability to inhibit biofilm formation, a critical factor in managing chronic infections. In wound infection models, AZM-BIC reduced the bacterial burden and enhanced wound healing. These findings establish AZM-BIC as a promising therapeutic approach, offering a targeted, effective solution for pulmonary infection management and wound care amid the growing threat of antimicrobial resistance. Furthermore, given that azithromycin is a well-established antibiotic and bicarbonate is a physiological component that is safe and well-tolerated, AZM-BIC represents a readily translatable strategy for clinical implementation.

The identification of a transient receptor potential ion channel of the melastatin subfamily activated by praziquantel (TRPM_PZQ) has opened new opportunities for target-based schistosomiasis drug discovery. In this study, eight new 1H-1,2,3-triazole derivatives of praziquantel (PZQ), and their synthetic intermediates, were prepared and evaluated for their schistosomicidal activity on schistosomula, juvenile, and adult Schistosoma mansoni. Their ability to activate schistosome wild-type (WT) and mutant TRPM_PZQ (Sm.TRPM_PZQ), as well as a schistosome TRPM channel activated by meclonazepam (Sm.TRPM_MCLZ), and TRPM_PZQ from Fasciola hepatica (Fh.TRPM_PZQ) and Echinococcus granulosus (Eg.TRPM_PZQ), was also assessed. Initial screening of schistosomula identified six compounds significantly affecting parasite motility/morphology at 25-50 μM. Compounds 3, 4, and 5e were active against juveniles by two orthogonal methods. All compounds impaired adult worm motility, with 4 being the most potent in males (EC₅₀: 1.3-2.3 μM) and 5e being the most potent in females (EC₅₀: 3.1-3.9 μM). Compound 5e showed the highest selectivity indexes (75 for females and 155 for males) when compared with the HepG2 human cell line. Compounds 2, 3, 4, and 5e activated WT (EC₅₀: 0.9-13.5 μM), and mutant Sm.TRPM_PZQ showing a similar activation profile to PZQ. Like PZQ, they did not activate Fh.TRPM_PZQ or Sm.TRPM_MCLZ at the tested concentrations but activated Eg.TRPM_PZQ with similar potencies to Sm.TRPM_PZQ. Molecular modeling studies suggest that the PZQ binding site on Sm.TRPM_PZQ may accommodate extended substituents on position 9 of the pyrazinoisoquinoline ring due to a conformational flexibility of the Y1517 side chain. This feature could be explored to design new PZQ analogues with improved drug metabolism and pharmacokinetic properties.

Chagas disease (CD), caused by the parasite Trypanosoma cruzi, affects millions of people worldwide and often leads to fatal heart damage. The course of CD is influenced by how the immune system is tuned, which can protect the host and favor parasite persistence. Interleukin-33 (IL-33) is an alarmin released upon tissue injury that signals through the ST2 receptor, exerting context-dependent regulatory or pathogenic effects. However, the role of the IL-33/ST2 axis in T. cruzi-induced myocarditis remains unclear. Here, using ST2-deficient (ST2^–/–) and wild-type (WT) female mice infected with the T. cruzi Y strain, we investigated its contribution to cardiac inflammation, tissue damage, and parasite burden. We found that ST2 signaling was not essential for controlling parasitemia, but its deficiency led to early onset myocarditis, disorganized fibrosis, and distinct electrical conduction. This severe immunopathology was driven by a remodeling of the cardiac immune landscape, with ST2^–/– mice exhibiting an influx of IFN-γ-producing monocytes and a shift in resident and monocyte-derived macrophages toward a pathogenic, pro-inflammatory phenotype. Likewise, the cardiac T cell compartment, including both conventional and γδ T cells, was skewed toward an inflammatory, IFN-γ-driven profile. However, infected ST2-deficient mice also displayed higher cardiac parasite burden and impaired nitric oxide production, indicating a dysfunctional response in parasite control. Together, these findings demonstrate that the IL-33/ST2 axis limits early systemic inflammation, orchestrates cardiac immune response, and protects against immunopathology and electrical remodeling during T. cruzi experimental infection. Targeting this pathway may offer therapeutic potential for preventing cardiac damage in CD.

Genome mining of Streptomyces sp. H-KF8 combined with sequence engineering yielded two serum-stable, noncytotoxic, nonlytic antimicrobial peptides, L3 and L3-K. Initial studies in uropathogenic Escherichia coli suggested membrane effects and nucleoid relaxation, prompting a comprehensive investigation of their mode of action. In this study tandem mass tag (TMT)-based quantitative proteomics revealed extensive proteome remodeling, with 175 and 120 differentially expressed proteins (DEPs) after treatment with L3 and L3-K, respectively. L3 induced predominantly upregulated responses linked to metabolism, RNA processing, transport, and homeostasis, whereas L3-K mainly caused the downregulation of proteins involved in metabolism, transport, and cell structure. Both peptides disrupted ABC transporter-mediated nutrient uptake and elicited stress responses, while L3 specifically perturbed the mal regulon, indicative of broader transcriptional dysregulation. Complementary fluorescent dye displacement and in vitro transcription/translation assays demonstrated nonspecific DNA binding, stronger for L3 than L3-K, and potent inhibition of transcriptional and translational processes. Strikingly, inhibitory concentrations paralleled their minimum inhibitory concentrations, directly linking DNA binding and interference with central information processing to antimicrobial activity. These findings reveal that L3 and L3-K primarily act by targeting DNA and interfering with the transcription-translation machinery. Beyond offering mechanistic insights, this study underscores peptides’ potential to act as scaffolds for next-generation antimicrobial peptides with DNA-binding and nonmembrane-lytic activity.