Xiaofen Liu

Treatment for elderly patients with pulmonary tuberculosis (PTB) is challenging due to poor efficacy and tolerance. The aim of this study is to preliminarily screen candidate regimens for elderly patients with drug-sensitive PTB. Candidate regimens were initially screened using the artificial-intelligence-enabled phenotypic response surface (AI-PRS) platform and in vitro experiments. The hepatorenal cytotoxicity of drug combinations was assessed with HEK293T and THLE-2 cells. In the in vivo validation stage, aged mice with airway Mycobacterium tuberculosis (Mtb) infection received the novel regimens by oral gavage for 4 weeks, while isoniazid (H)/rifampicin (R)/ethambutol (E)/pyrazinamide (Z) served as the standard regimen control. Hepatorenal function was monitored during the treatment to assess drug safety, and pathological HE staining was also performed to evaluate liver and kidney damage. Bacterial loads in the lungs and spleens were evaluated using colony-forming unit (CFU) assays. After three rounds of AI-PRS analysis and MIC screening in vitro, three optimized treatment regimens were identified including delamanid (Dlm)/bedaquiline (Bdq)/pretomanid (Pa) combined with rifapentine (Rpt), pasiniazid (PAS-H) and levofloxacin (Lfx). After validation with an experiment on aged mice, the Bdq-containing regimen resulted in the mildest pulmonary inflammation and the lowest bacterial loads in lungs and spleens. The bacterial burden was similar between Bdq- and Dlm-containing regimens, which presented stronger bactericidal activity over the HREZ regimen. Regarding drug safety evaluation, the Bdq-containing regimen showed no marked hepatotoxicity and nephrotoxicity in our preclinical models, while other regimens showed variable abnormalities in serum biochemical indices. The Bdq/Lfx/PAS-H/Rpt regimen presented high efficacy and more favorable safety in aged mice compared with the standard regimen, considered as a promising preclinical candidate for elderly patients with drug-sensitive TB and deserving of further clinical trials for evaluation.

Nemonoxacin, a novel non-fluorinated quinolone, is approved for community-acquired pneumonia, but its efficacy against uncomplicated urinary tract infections (uUTIs) caused by Escherichia coli ( E. coli ) is uncertain. We aimed to establish an in vitro uUTIs model simulating urinary concentrations to evaluate dosing regimens. An in vitro model was developed using cation-adjusted Mueller–Hinton broth (CAMHB) and synthetic human urine (SHU) to reproduce urinary exposure. The model was applied to 12 E. coli clinical isolates and ATCC 25922 (MICs 512 mg/L) over 24 h. The effects of medium type on MICs and bacterial growth were assessed. Pharmacokinetics/pharmacodynamics (PK/PD) relationships were described using a sigmoid E _max model, with change in bacterial density (Δlog ₁₀ CFU/mL) and the area under the bacterial kill curve (AUBKC) as efficacy endpoints. Monte Carlo simulation (MCS) estimated the probability of target attainment (PTA) and cumulative fraction of response (CFR) for 500 mg and 750 mg once-daily regimens. Nemonoxacin MICs were higher in SHU, and bacterial growth showed early inhibition. The AUC _0–24 /MIC ratio best correlated with antibacterial effect ( R ² = 0.951 in CAMHB; 0.982 in SHU). For a 1-log CFU reduction, AUC _0–24 /MIC targets were 46.5 in CAMHB and 199 in SHU. The 500 mg regimen achieved ≥90% PTA for isolates with MIC ≤ 16 mg/L (CFR 92.1%) using CAMHB-derived targets but only ≤8 mg/L (CFR 59.4%) in SHU. A 500 mg once-daily regimen of nemonoxacin appears to be a promising therapeutic option for the treatment of uUTIs, although further clinical studies are necessary to validate these findings.

This study aimed to construct a genome-scale metabolic model (GSMM) for Acinetobacter baumannii and integrate transcriptomic data from colistin, sulbactam, and their combination to delineate the mechanism of synergistic metabolic perturbations. A GSMM of A. baumannii 163560 was reconstructed with CarveMe and curated using literature and Biolog assays. Transcriptomic data under different antibiotic treatments were integrated with the model using RIPTiDe, and flux variability analysis was conducted to identify metabolic perturbations across monotherapies and combination therapies. The curated model (2,103 reactions, 1,492 metabolites, and 1,033 genes) achieved prediction accuracies of 80% for gene essentiality and 80.5% for carbon source utilization. Transcriptomic constraints substantially reduced the active network across all treatments while retaining core pathways such as the TCA cycle and amino acid metabolism. Colistin uniquely activated the glyoxylate cycle, consistent with a stress-adaptive bypass of central carbon metabolism. In contrast, the colistin-sulbactam combination induced distinct shifts toward amino acid, nucleotide, and ion metabolism, with aspartate-related pathways showing characteristic flux increases. Flux variation analysis further demonstrated enhanced TCA cycle activity under colistin and combination therapy, likely reflecting an oxidative stress response. Combination treatment also revealed unique essential reactions involving nucleotide and amino acid biosynthesis. Colistin and sulbactam elicit distinct metabolic rewiring in A. baumannii . Combination therapy drives a shift from central carbon metabolism toward amino acid and ion metabolism. Enzymes such as isocitrate lyase, malate synthase, and aspartate deaminase—absent in mammals—represent potential targets to enhance synergistic antibacterial effects.

Background: Eravacycline exhibits potent activity against multidrug-resistant pathogens and holds promise for the management of hospital-acquired and ventilator-associated pneumonia (HAP/VAP). However, sensitive and robust bioanalytical methods to quantify eravacycline in human pulmonary epithelial lining fluid (ELF) for pharmacokinetic (PK) and pulmonary penetration studies in these infections remain limited. Methodology: A simple, rapid, and sensitive LC-MS/MS method was developed for the quantification of eravacycline in bronchoalveolar lavage fluid (BALF). Using urea as a volume normalizer, ELF concentrations were calculated from the eravacycline concentrations in BALF. This method was applied in a clinical study evaluating the pulmonary penetration after intravenous infusion in patients with HAP and VAP. Results: The developed LC-MS/MS method exhibited good linearity in the range of 1–200 ng/mL for quantifying eravacycline in BALF. In BALF, intra-day precision ranged from 1.4% to 6.0%, and inter-day precision from 1.6% to 9.9%, with accuracy between 98.0% and 102.4%. Matrix effects were within 97.4% to 107.6% for BALF samples from six different individuals, with extraction recoveries ranging from 103.5% to 107.2%. Stability studies demonstrated that eravacycline remained stable under various conditions, including storage at room temperature, freeze–thaw cycles, long-term (–70 °C) storage, and post-treatment handling. The method was successfully applied to clinical samples from four HAP or VAP patients, with measured eravacycline pulmonary penetration ratios of 4.29, 17.40, 5.22 and 4.70, indicating efficient pulmonary distribution. The measured eravacycline concentrations ranged from 0.0243 to 0.0436 μg/mL in BALF. The corresponding urea-corrected ELF concentrations ranged from 0.570 to 1.617 μg/mL. Conclusions: This study described a detailed and validated method for quantifying eravacycline concentrations in ELF from patients, providing a reliable analytical approach for investigating the pulmonary distribution of eravacycline.

MRX-8 is a new next-generation polymyxin with potent antibacterial activity against carbapenem-resistant Acinetobacter baumannii (CRAB). This study evaluated the MRX-8 and meropenem combination and their dosing regimens against CRAB in clinics. Seven CRAB strains isolated from Huashan Hospital were tested. Two strains of AB21-3881 and AB21-3759 were selected for static time-kill and the Hollow Fiber Infection Model (HFIM). Adaptive resistance to MRX-8 was assessed via population analysis profiling (PAP) at 2 mg/L of MRX-8. Multilocus sequence typing identified all seven strains as ST2. Minimum inhibitory concentration values for MRX-8 ranged from 0.5 to 1 mg/L. Synergy was observed in six out of seven (85.7%) strains. The combination of 1 mg/L MRX-8 with 1 mg/L meropenem completely inhibited bacterial growth within 24 h for both selected strains. In HFIM, the combination of MRX-8 (0.75 mg/kg q8h continuous infusion) and meropenem (1 g q6h continuous infusion) achieved synergistic killing over 72 h for AB21-3759, while single treatment of MRX-8 (0.75 mg/kg q8h continuous infusion) achieved bactericidal effect (lower than the detect limitation) over 72 h. PAP analysis demonstrated that the combinational therapy could delay the emergence of adaptive resistance sub-populations by 12–24 h. The combination of MRX-8 and meropenem demonstrated synergistic bactericidal activity by checkerboard and static time-kill curves. Additionally, in HFIM, MRX-8 at 1 mg/kg q12h combined with meropenem at 2 g q12h, as well as MRX-8 at 0.75 mg/kg q8h continuous infusion combined with meropenem at 1 g q6h continuous infusion, achieved bacteriostatic killing at 72 h compared to the initial inoculum.

Nephrotoxicity has seriously affected the clinical application of colistin methanesulphonate (CMS). Colistin B methanesulphonate (CMS-E2) is a novel polymyxin developed and aimed to have lower nephrotoxicity. This study aimed to investigate the relationships between pharmacokinetics (PK) and nephrotoxicity of CMS and CMS-E2 and compare the toxicity of the two drugs in rats. Rats were treated intraperitoneally with a single dose of saline, CMS [10, 20 mg/kg of colistin base activity (CBA)], and CMS-E2 (20, 40 mg/kg CBA). An LC-MS/MS method was developed to determine plasma and renal tissue concentrations of CMS/CMS-E2 and colistin/colistin B. The severity of renal injuries was examined both biochemically and histologically. The PK-toxicodynamic (TD) model was evaluated to characterize the PK of CMS/CMS-E2 and colistin/colistin B in plasma as well as its relationship with nephrotoxicity. Creatinine (CR) and blood urea nitrogen (BUN) profiles were described using an indirect link PK-TD model, with linear-effect relationship. Both the slope between colistin or colistin B concentrations in the effect compartment and CR, BUN was significantly lower for CMS-E2 compared with CMS (CR: P = 0.027, BUN: P = 0.043). The concentrations of colistin and colistin B in kidneys were correlated with CR, BUN values, and histologic examination scores. The regression coefficient of CMS-E2 between the colistin B concentrations in renal tissues and CR, BUN values were lower, as well (CR: P = 0.003, BUN: P = 0.001). The renal injuries induced by CMS and CMS-E2 lagged behind the change of plasma colistin or colistin B concentrations and correlated to those in kidneys. CMS-E2 showed significantly lower nephrotoxicity compared to CMS in vivo.

Polymyxin B, a last resort for carbapenem-resistant gram-negative bacteria (CRGNB) infections, has infection site-specific pharmacokinetic/pharmacodynamic (PK/PD) properties. However, there is little clinical evidence to support optimal exposures of polymyxin B for different site infections. We performed a prospective, observational, multicenter study to evaluate the clinical outcomes and PK/PD of intravenous polymyxin B treatment for various site CRGNB infections. The main clinical outcomes were 14-day all-cause mortality and nephrotoxicity, and the secondary outcomes were 28-day mortality and clinical response. The area under curves (AUCs) of polymyxin B were determined, and their associations with clinical outcomes were analyzed by stratification based on the infection site. A total of 312 patients were ultimately enrolled from 10 research centers. The overall 14-day mortality was 29.5%, and those of patients with lower respiratory tract infection (LRTI), intra-abdominal infection (IAI), and bloodstream infection (BSI) were 32.3%, 19.7%, and 30.3%, respectively. The 28-day mortality rate was 38.1%, while LRTI patients had the highest mortality (41.4%) and IAI patients lowest (34.8%). The clinical response rate was 46.2%, which was similar among the subgroups. The overall AKI rate was 60.9%. An AUC greater than 50 mg∙h/L was related to lower mortality in IAI patients but not in LRTI patients, which led to a lower but not significant difference in the overall analysis. The AUC of polymyxin B was an independent risk factor for 14-day mortality in IAI patients, and the cutoff value was 76 mg∙h/L. The results would be helpful for personalized dosing and monitoring of polymyxin B. CLINICAL TRIALS: This study is registered with the Chinese Clinical Trial Registry as ChiCTR2200056667 .