Antimicrobial Agents and Chemotherapy最新文献

The fungal disease mucormycosis, while generally regarded as rare and not transmitted between individuals, has become increasingly prevalent in disaster areas, among the immunocompromised, and in diabetics especially in response to COVID-19. Treatment options are limited. These include debridement of necrotizing tissue followed by complicated multicomponent therapies with amphotericin B and selected azole drugs, usually having poor outcomes. Mucormycetes are intrinsically resistant to the widely used short-tailed azole drugs fluconazole and voriconazole, but susceptible to the long-tailed, though expensive, azole posaconazole. Knowledge of the crystal structure of Saccharomyces cerevisiae sterol 14α-demethylase (Erg11, Cyp51) led to the hypothesis that this pattern of intrinsic azole resistance and susceptibility is due to the Rhizopus arrhizus CYP51-F5 isoform residues F129 and A291, while the CYP51-F1 isoform residues Y127 and V291 confer susceptibility to both short- and long-tailed azole drugs. The heterologous overexpression of individual recombinant R. arrhizus CYP51 isoforms in a S. cerevisiae host, with or without the cognate NADPH-cytochrome P450 reductase (RaCPR), and selective genetic modification of CYP51-F5 have tested this hypothesis. Complementary gene deletion experiments in Rhizopus microsporus confirm that the amino acid residues that align with R. arrhizus CYP51-F5 F129 and A291 determine the resistance or susceptibility pattern of R. arrhizus to short-, medium-, and long-tailed azoles.

Hematological patients with febrile neutropenia receiving piperacillin-tazobactam may experience pharmacokinetic alterations that compromise drug exposure. We aimed to characterize the population pharmacokinetics of piperacillin in plasma and provide optimized dosing recommendations for this patient population. A population pharmacokinetic analysis was conducted in patients who received piperacillin-tazobactam as part of the BEATLE study, which compared the efficacy, safety, and pharmacokinetic/pharmacodynamic target attainment of β-lactams administered in extended infusion versus short 30 min infusion in adult hematological patients with febrile neutropenia. Monte Carlo simulations were performed to evaluate, for each dosing regimen, the probability of attaining (i) an efficacy target of unbound piperacillin concentrations above the minimum inhibitory concentration (MIC) of the bacteria for the entire dosing interval (100% ƒT_>MIC), and (ii) a toxicity threshold of ≥160 mg/L. A total of 44 patients and 221 plasma concentrations were included. A one-compartment model best described piperacillin plasma pharmacokinetics, with Cockcroft-Gault creatinine clearance (CrCL) significantly influencing drug clearance. Dosing simulations showed that extended and continuous infusions were superior to short 30 min infusions in the attainment of 100% ƒT_>MIC, even for bacteria with low to intermediate MIC (≤2-4 mg/L). In patients with higher CrCL (>90 mL/min) or infections caused by less susceptible Gram-negative bacilli (MIC: 8-16 mg/L), only continuous infusions of 12-16 g/day were likely to achieve 100% ƒT_>MIC. These findings support the use of extended or continuous infusions of piperacillin in the initial management of patients with febrile neutropenia, particularly in patients with higher CrCL or when infections caused by less susceptible pathogens, such as Pseudomonas aeruginosa, are suspected.

The mechanism of action of integrase strand transfer inhibitors involves binding to magnesium ions in the active site of the HIV integrase enzyme, making them susceptible to chelation-type drug-drug interactions with metal cation-containing medications. This study evaluated the potential of metal cation-containing antacids and mineral supplements to impact bictegravir (BIC) exposure and assessed alternative approaches for combined use. This was an open-label, single-dose, Phase 1 study in adult participants without HIV. The pharmacokinetics and safety of BIC (administered as part of a single-tablet combination with emtricitabine [F] and tenofovir alafenamide [TAF; B/F/TAF]) were assessed when co-administered with maximum-strength aluminum/magnesium-containing antacid (referred to as "aluminum/magnesium-containing antacid"), calcium carbonate, or ferrous fumarate under fasted and fed conditions, and administered 2 hours before or after the antacid. Pharmacokinetic parameters were compared using analysis of variance to calculate geometric least-squares mean ratios and 90% confidence intervals. Forty-two participants were enrolled. BIC exposure (area under the plasma concentration-time curve extrapolated to infinity) was reduced by 79%, 33%, and 63%, respectively, when co-administered with aluminum/magnesium-containing antacid, calcium carbonate, and ferrous fumarate under fasted conditions. Co-administration of B/F/TAF with calcium carbonate or ferrous fumarate with a meal and administration of B/F/TAF 2 hours before the antacid reduced the impact of the interactions. B/F/TAF was well tolerated alone or in combination with metal cation-containing medications. Co-administration of BIC and calcium/iron-containing supplements with a meal and administration of BIC 2 hours or more before aluminum/magnesium-containing antacids are some of the effective strategies to mitigate chelation effects on BIC exposure.This study was registered at NCT05502341/NCT06333808.

Subcutaneous delivery of antibiotics is a practical alternative to intravenous administration. Ceftriaxone is commonly used for a variety of infections with limited data on the safety and pharmacokinetics of a 2 g subcutaneous dose. This was a prospective, self-controlled cross-over study in 20 stable inpatients receiving ceftriaxone for their infection. Following an intravenous dose, participants received a single dose of 2 g subcutaneous ceftriaxone, in 50 mL normal saline via gravity feed. Capillary dried blood spots were collected at baseline, 1, 2, 4, 8, and 24 hours following the subcutaneous and intravenous doses. Pain scores and infusion site reactions (edema/erythema) were assessed. Ceftriaxone concentrations were measured using a validated liquid chromatography-tandem mass spectrometry assay. A population pharmacokinetic model was developed using nonlinear mixed-effects modeling. The highest median (interquartile range) pain score within the first 2 hours following infusion of a subcutaneous dose of 2 g ceftriaxone was 2.5 (1-4). All participants were pain-free 4 hours after the infusion. The estimated bioavailability was 95.7% (95% bootstrap interval 90.3-99.5). Compared with intravenous, subcutaneous administration resulted in lower peak and comparable trough concentrations. The probability of target attainment for free drug concentrations was similar to intravenous administration for most common infections in hospitalized patients. Subcutaneous administration of 2 g ceftriaxone is well tolerated and has a comparable pharmacokinetic profile relative to intravenous dosing in non-critically ill patients with severe infections.IMPORTANCEThis prospective, self-controlled cross-over design study demonstrates that subcutaneous administration of 2 g ceftriaxone appears safe and well tolerated with a comparable pharmacokinetic profile relative to intravenous dosing in non-critically ill patients with severe infections.CLINICAL TRIALSThis study was registered at ACTRN12624000692538.

Conventionally, susceptibility testing and pharmacokinetic/pharmacodynamic relationships are determined using standard inoculum (i.e., 10⁵-10⁶ CFU). These may be poorly predictive of efficacy for high-inoculum infections, especially amongst β-lactamase-producing organisms. A. J. Kunz-Coyne, R. Gray, E. May, H. Curry, et al. (Antimicrob Agents Chemother 69:e01170-25, 2025, https://doi.org/10.1128/aac.01170-25) used a 96-h simulated endocardial vegetation model to describe pharmacodynamic efficacy, resistance emergence, and β-lactamase expression that resulted after clinically relevant exposures of antibiotics against three Enterobacter cloacae complex isolates, demonstrating that MIC values were often poorly predictive of efficacy in the model.

Gepotidacin is a novel first-in-class triazaacenaphthylene antibiotic developed for the treatment of uncomplicated gonorrhea and uncomplicated urinary tract infections (uUTIs). To support uUTI, in vivo pharmacokinetics (PK)/pharmacodynamics (PD) studies have been conducted in the murine neutropenic thigh infection model evaluating gepotidacin against 17 isolates of Escherichia coli and 7 isolates of Klebsiella pneumoniae having MICs of 0.25 to 16 µg/mL. Exposure data were fit using a population PK model, and efficacy data were fit with an inhibitory effect sigmoid Imax model using free-drug area under the concentration-time curve (fAUC)/MIC as the primary index. The ratios associated with response were determined for each isolate, and the median fAUC/MIC (excluding strains with <1-log of growth from baseline) was 13. To retain the data for all isolates, an exploratory analysis was conducted using different criteria to determine the target for strains with <1-log of growth (6 of the 24 strains tested). While the median fAUC/MIC was similar regardless of the criteria used, this analysis highlights the importance of critically reviewing PK/PD data for trends related to isolate characteristics and/or individual study outputs. As previously reported, the systemic targets determined from PK/PD studies were applied to urine concentrations for probability of target attainment analyses, which led to successful clinical trials and regulatory approval for gepotidacin in the treatment of uUTI. However, further work is needed to confirm the translational validity of these approaches on a broader scale and their application in establishing PK/PD targets for cystitis.

Chagas disease, caused by Trypanosoma cruzi, is a neglected parasitic infection. The very limited arsenal of anti-T. cruzi treatments calls for the development of new drugs. Recently, a library of 3-benzylmenadione derivatives was synthesized, with cruzidione being the most efficient and specific compound against the parasite. To decipher its mode of action, we used the yeast Saccharomyces cerevisiae as a model. Evidence pinpointed at the heme A synthase Cox15 as a primary target of cruzidione: (i) a mutation in Cox15 (i.e., S429F) renders the yeast cells highly sensitive to the drug, (ii) treatment with cruzidione led to the loss of cytochrome c oxidase, an enzyme that relies on heme A as an essential cofactor, and (iii) replacement of the yeast Cox15 by T. cruzi enzyme resulted in a high sensitivity to cruzidione. We then investigated the effect of cruzidione in T. cruzi and observed a significant reduction in the heme contents, most likely involving the inhibition of the heme A synthase. This, in turn, led to a decrease in O₂ consumption by the parasite. Finally, using the yeast model, we showed that, similar to what we previously found for the antimalarial benzylmenadione plasmodione, NADH-dehydrogenase plays a key role in cruzidione bioactivation. We proposed that the reduced benzoylmenadione metabolites, produced by the reaction with NADH-dehydrogenase, act as Cox15 inhibitors. This study, through the identification of the mode of action of cruzidione, highlighted Cox15 as a novel target for antiparasitic drugs.

Bacteriophage (phage) therapy holds great promise for treating antimicrobial-resistant infections. However, the pharmacokinetics (PK) of phage have been difficult to characterize due to a lack of standardized protocols for phage purification, labeling, and in vivo quantification. Here, we present robust methods for ultrapure phage preparation, as well as non-destructive, highly stable attachment of radio-iodide to phage using a well-described Sulfo-SHPP linker. We purified and radiolabeled the phage strains, PAML-31-1, OMKO1, and Luz24, lytic to drug-resistant Pseudomonas aeruginosa, for biodistribution assay in normal young adult CD-1 mice injected via intravenous injection. Groups of five mice were euthanized, and tissues/organs were removed for weighing and scintillation well counting of ¹²⁵I activity. A physiologically based PK model was then constructed, focusing on compartments describing blood, lung, muscle, bone, liver, stomach, spleen, small intestines, large intestines, and kidney. Tissue partition coefficients (K_P) were estimated for high-perfusion organs (lung and kidney) as 0.000138, GI organs (liver, spleen, and stomach) as 0.627, and all other organs as 0.220. Monte Carlo simulations predicted rapid elimination of phage in humans, with blood concentrations being <10² PFU/mL by 12 h, whereas simulated multi-dose regimens and continuous infusion regimens were predicted to have sustained concentrations. Our physiologically based PK model of phage represents the first rigorous preclinical assessment of phage PK utilizing contemporary pharmacometric approaches amenable to both preclinical and clinical study design.

Randomized clinical trials are the gold standard for evaluating the benefits and harms of interventions and yet may not provide the evidence needed to inform medical decision-making, an ultimate goal for clinical research. Commonly used design and analysis approaches are often not suited to answer the most important questions to inform clinical practice, specifically how do resulting patient experiences, when comprehensively considering benefits and harms, compare between therapeutic alternatives? The standard approach of siloed analysis of one outcome at a time: (i) does not incorporate associations between multiple outcomes; (ii) does not recognize the cumulative nature of multiple outcomes in individual patients or recognize important gradations of global patient response; (iii) suffers from competing risk complexities during interpretation of individual outcomes; (iv) provides for ambiguous generalizability with respect to benefit:risk since efficacy and safety analyses are often conducted on different populations. Evaluation of treatment effect heterogeneity to identify subgroups for treatment or avoidance of treatment is typically evaluated based on a single efficacy or safety endpoint and rarely evaluated based on the overall benefit:risk. Methods that quantify and compare the patient experience are needed. The desirability of outcome ranking (DOOR) is a paradigm for the design, monitoring, analysis, interpretation, and reporting of clinical trials and other research studies based on patient-centric benefit:risk evaluation, developed to address these issues and advance clinical trial science. Aligning the clinical research strategy with the relevant question for clinical practice will enhance research applicability. Careful design and comprehensive analyses are critical for DOOR paradigm application. We provide a recommended statistical analysis plan for research studies implementing DOOR, describe its elements, and illustrate analysis application using examples. A freely available online tool for the recommended analyses and the design of studies implementing the DOOR paradigm is provided.

Wild-type LRA-5, recovered from Alaskan soil samples, shares no more than 33% amino acid sequence identity with enzymes from pathogens like PER β-lactamases. Recombinant E. coli expressing wild-type LRA-5 and its engineered variants LRA-5^Y69Q and LRA-5^V166E showed MIC values equivalent to control strains. However, LRA-5^Y69Q/V166E displayed MICs above the resistant breakpoint for some β-lactams. Kinetic parameters correlated with the MICs, showing that the catalytic efficiency of LRA-5^Y69Q/V166E was comparable to those from class A β-lactamases, such as CTX-M-15, PER-2, and KPC-2. LRA-5^Y69Q/V166E exhibited k_cat/K_m values up to 11,000-fold higher compared to wild-type LRA-5, which is associated with the presence of Glu166. The X-ray crystallographic structure of wild-type LRA-5 (1.80 Å; PDB 8EO5) shows that the lack of both Glu166 and a deacylation water molecule contributes to a biologically insignificant activity. Interactions observed between LRA-5 and ceftazidime (2.35 Å; PDB 8EO6) show structural conservation with other β-lactamases. In contrast, the crystallographic structure of LRA-5^Y69Q/V166E (2.15 Å; PDB 8EO7) bears a deacylation water molecule that is associated with the increase in catalytic activity compared to the wild-type variant. Circular dichroism results confirm that amino acid substitutions in LRA-5 do not affect the overall content of the secondary/tertiary structures. Evidence suggests that alternative evolutionary paths could have occurred for β-lactamases like LRA-5, produced by environmental microorganisms: (i) proteins having similar structural features than active β-lactamases may accumulate a small number of mutations (e.g., Y69Q/V166E) to yield active enzymes and (ii) the β-lactamase fold may have lost key residues in the absence of antibiotics.