Antimicrobial Agents and Chemotherapy最新文献

HIV-1 treatment has advanced with various antiretroviral regimens. Although efavirenz (EFV)-based regimens have been widely used, current guidelines recommend integrase strand transfer inhibitor (INSTI)-based therapy as first-line. However, INSTI may cause weight gain and adverse lipid changes, creating new unmet metabolic needs. Novel agents like ainuovirine (ANV), a non-nucleoside reverse transcriptase inhibitor (NNRTI), may offer effective virological suppression (VS) with improved tolerability, but their long-term real-world safety and effectiveness remain unclear. This was a multicenter, retrospective observational cohort study. Virologically suppressed adults on a tenofovir disoproxil fumarate (TDF)/3TC+EFV regimen were either switched to TDF/3TC+ANV (ANV group) based on the physician's discretion or continued on TDF/3TC+EFV (EFV group). Baseline demographic and clinical data were collected, and participants were followed for 48 weeks. The primary effectiveness outcome was the proportion of patients achieving HIV-1 RNA levels below the limit of quantification (LOQ) at week 48. Secondary outcomes included absolute or percentage changes from baseline in CD4+ T-cell count, CD4+/CD8+ ratio. Key secondary safety outcomes included absolute changes from baseline in body weight, BMI, fasting lipid profiles (total cholesterol [TC], triglycerides [TG], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C]), and parameters of liver and renal function. A total of 350 participants who completed the 48-week follow-up were included, comprising 170 patients in the ANV group and 180 patients who remained on EFV. At week 48, the proportion of VS was 96.5% in the ANV group and 96.1% in the EFV group (difference: 1.00 percentage points; 95% CI: -2.77 to 2.77), confirming non-inferiority. No significant differences in CD4+ T-cell recovery or CD4+/CD8+ ratios were observed. The ANV group experienced significantly less weight gain than the EFV group (estimated treatment difference [ETD]: -0.79 kg; P < 0.001). A corresponding trend in BMI change was observed but did not reach statistical significance. ANV also led to more favorable lipid changes, including a significant reduction in total cholesterol (ETD: -0.52 mmol/L; P < 0.001) and triglycerides (ETD: -0.83 mmol/L; P < 0.001) compared to EFV. Liver and renal function profiles remained stable in both groups. Switching from EFV- to an ANV-based regimen effectively maintained VS and led to improved metabolic parameters, including less weight gain and a more favorable lipid profile. As an alternative switch strategy, the ANV-based regimen may be a more beneficial option for people living with HIV (PLWH) who are at high risk of weight-related or dyslipidemia-associated comorbidities.

Colistin is considered one of the last-resort antibiotics for treating infections caused by multidrug-resistant (MDR) Gram-negative bacteria. However, the emergence and dissemination of mobile colistin resistance gene, mcr, have severely compromised the clinical utility of colistin. Combination therapy has emerged as a promising strategy to restore and enhance antibiotic efficacy against such bacterial infections. In this study, we identified broxyquinoline (BRO), an antiprotozoal compound, as a potent colistin adjuvant that significantly enhanced colistin activity against both colistin-susceptible and colistin-resistant Gram-negative bacteria by markedly reducing the minimum inhibitory concentration. Mechanistically, BRO disrupts bacterial membrane integrity, increases membrane permeability and fluidity, collapses the proton motive force, induces reactive oxygen species (ROS) accumulation, and depletes intracellular ATP, collectively disturbing bacterial homeostasis. Additionally, BRO exhibited high-affinity binding to lipopolysaccharide (LPS) and attenuated subsequent LPS-induced inflammatory responses in host cells. In murine thigh and lung infection models, the BRO-colistin combination restored colistin efficacy in vivo, evidenced by significantly reduced bacterial loads. In the lung infection model, this combination further improved survival, alleviated pulmonary pathological damage, and reduced the levels of pro-inflammatory cytokines (TNF-α, IL-1β) in bronchoalveolar lavage fluid. Collectively, these findings support the BRO-colistin combination as a promising therapeutic strategy to overcome colistin resistance and combat MDR Gram-negative infections.

The World Health Organization has flagged the rise of drug resistance in Aspergillus fumigatus as a critical concern. Elevated mutation rates in this pathogen contribute to the rapid development of resistance, complicating treatment efforts. We conducted a study on the prevalence of azole resistance among clinical A. fumigatus isolates in the Netherlands from 1994 to 2022 and identified 34 cyp51A variants. To investigate the impact of individual single-nucleotide polymorphisms (SNPs) and combinations thereof on the azole phenotype in TR₃₄-mediated resistance genotypes, we focused on novel, recent mutations and explored the effects of SNPs L98H, T289A, I364V, and G448S and the combination of the mutations TR₃₄/L98H, TR₃₄/L98H/T289A/G448S, and TR₃₄/L98H/T289A/I364V/G448S on azole affinity and susceptibility. We created the three-dimensional protein model of the Cyp51A protein with azoles, and the mutation was introduced to the wild-type cyp51A A. fumigatus strain by the CRISPR-Cas9 gene editing technique. Finally, in vitro susceptibility testing of A. fumigatus strains carrying the mutations was conducted to confirm the azole phenotypes observed in clinical isolates. The MICs of all four azoles against the mutated cyp51A strains, which harbored combination mutations, were higher than those of the wild type, with highly elevated MICs of itraconazole, voriconazole, and isavuconazole. Genotypes TR₃₄/L98H/T289A/I364V/G448S mutant showed a consistent phenotype to the clinical strains, which are highly resistant to voriconazole but susceptible to itraconazole. In this study, we show that molecular dynamics simulations of amino acid substitutions in the cyp51A gene correlate to the structure-function relationship of in vitro phenotype.

Hematology patients are highly susceptible to severe bacterial infections, particularly those caused by multidrug-resistant (MDR) gram-negative pathogens, which are associated with significant morbidity and mortality. Eravacycline, a novel fluorocycline antibiotic, demonstrates broad-spectrum activity against MDR bacteria. This real-world study aimed to evaluate the effectiveness and safety of eravacycline in Chinese hematology patients. In this multicenter, retrospective study, hematology patients receiving ≥3 days of eravacycline between September 2023 and September 2024 were included. The outcomes included clinical response rate, microbiological response rate, and safety. Of 796 patients included, most had hematological diseases (94.6%) and recent chemotherapy or radiotherapy (80.2%). The most common infection was pneumonia (57.4%), and sputum (47.2%) was the most frequent specimen type for pathogen isolation. Among 481 patients with microbiological examination results, Klebsiella pneumoniae (30.5%) and Acinetobacter baumannii (17.4%) were predominant. The mean time to defervescence was 3.2 ± 2.1 days. The overall clinical response rate was 88.8%, with response rates of 84.0% in bloodstream infections and 87.5% in pulmonary infections. Microbiological response rate at the end of treatment was 90.7%. Eravacycline exhibited high susceptibility rates across A. baumannii (95.8%), K. pneumoniae (94.3%), and Staphylococcus aureus (100.0%). Only 2.5% of patients reported adverse events. Subgroup analysis showed that pulmonary diseases (P = 0.006), sepsis (P = 0.003), and duration ≤7 days (P < 0.001) of eravacycline 1 mg/kg/12 h were significantly associated with poorer clinical response rate at the end of treatment. Eravacycline demonstrated promising effectiveness and safety in treating infections of patients from the hematology department.

Antimicrobial resistance is a silent pandemic responsible for 1.14 million deaths worldwide in 2021, with a major contribution from Klebsiella pneumoniae. β-lactams are the most commonly used antibiotics in humans, and there is an urgent need to characterize the resistance mechanisms to these antibiotics in Enterobacterales other than Escherichia coli. Mecillinam is a narrow-spectrum β-lactam targeting a single penicillin-binding protein, PBP2. Pivmecillinam, its oral prodrug, is used as a first-line treatment for uncomplicated urinary tract infections. It has been used for decades in Europe but was only authorized by the US Food and Drug Administration in 2024. Here, we decipher mecillinam resistance mechanisms in K. pneumoniae by characterizing its resistome in a pan-susceptible strain. The chromosomally encoded SHV β-lactamase led to spontaneous mecillinam-resistant mutants appearing at a higher rate, growing faster and at higher mecillinam concentrations in K. pneumoniae than in E. coli. The most frequent genetic event was an unstable duplication leading to heteroresistance. The selected mutations leading to resistance affected a wide range of functions, with resistance being dependent or independent of the RelA (p)ppGpp synthetase. Through an in-depth characterization of six mutant strains, we showed that, in the presence of mecillinam, they all experienced different growth defects despite high minimal inhibitory concentrations. Overall, our results in K. pneumoniae suggest different mechanisms to escape the complex mode of action of β-lactams in synergy with the β-lactamase SHV.

Endoscope reprocessing is a time-consuming, multi-step process, and ongoing microbial surveillance is necessary to ensure effective reprocessing and safe storage. Despite this, traditional surveillance methods, such as cultures, are not often carried out due to time and cost constraints, providing only delayed end point results from specific locations, with no insight into biofilm formation, disinfection efficacy, or any variability related to device design. Within this study, the efficacy of plasma activated water (PAW) disinfection (and subsequent regrowth) within endoscopic test pieces was investigated using bacterial bioluminescence enabling real time and in situ monitoring of biofilm formation and treatment efficacy. Real time imaging of bioluminescent Pseudomonas aeruginosa PAO1 SEI MCS5-lite was used to track biofilm growth within translucent PVC endoscopic test pieces across regions of interest using analysis of bioluminescent intensity. Results demonstrated that biofilm accumulation was more prominent around connectors compared to other regions of the test pieces. Disinfection with PAW achieved a significant 96.45% reduction in biofilm density (determined by culture) and a 93.08% reduction in bioluminescence (relative light units). However, percentage reduction in bioluminescence ranged from 77% to 95% across regions indicating lack of uniformity of treatment. Subsequent testing with plasma activated disinfectant (PAD) showed consistent biofilm reduction across all regions, with no variability between connectors and other regions as observed with PAW and other treatments. In conclusion, bioluminescence can be used to assess efficacy of disinfectants and effect of endoscope design by tracking biofilm density in real time and in situ.

Cefiderocol (CFDC) is a promising drug for treating infections caused by Stenotrophomonas maltophilia, a multidrug-resistant pathogen. However, no evidence of its efficacy against S. maltophilia-induced hemorrhagic pneumonia has been reported. We compared the effects of CFDC and levofloxacin (LVFX) on improving survival as well as reducing bacterial load and pathological effects in a mouse model of S. maltophilia hemorrhagic pneumonia. The dosage of LVFX and CFDC was determined using a previously described method to establish S. maltophilia-induced hemorrhagic pneumonia in mice. CFDC and LVFX were administered intraperitoneally 3 h after bacterial infection. Treatment was administered using the calculated dosages. CFDC significantly improved survival, showed a tendency to reduce bacterial load in the blood and lungs, and revealed that hemorrhage was suppressed in pathological analysis compared with the control group. These results support the current recommendation for CFDC as a treatment option for S. maltophilia infections. However, its efficacy in our model was lower than that of LVFX. This may be due to the superior pulmonary tissue penetration of LVFX. Treatment strategies that consider tissue penetration are necessary for severe S. maltophilia infections. However, the use of LVFX must consider the risk of resistance development, whereas CFDC may be advantageous for treating resistant pathogens.

Use of mouse infection models for antimicrobial pharmacokinetic/pharmacodynamic (PK/PD) analysis can assist in dosing regimen design and susceptibility breakpoint development. A major hurdle for clinical translation of in vivo study output is defining the model endpoint linked to clinical success. Validation of the in vivo endpoint requires a clinical data set composed of success or failure linked to minimum inhibitory concentration (MIC), dosing regimen, and if possible human pharmacokinetic measures. The present studies utilized a clinical library of eight Aspergillus fumigatus strains in a mouse pneumonia model to define the endpoint associated with humanized treatment regimens of the triazole, posaconazole. This includes wild-type strains associated with successful treatment and strains with resistance mutations leading to elevated MICs and associated with treatment failure. We found humanized posaconazole exposures resulted in a net stasis or net decrease in organism burden in the animal model compared to the start of therapy for all wild-type strains. However, a net increase in organism burden despite treatment with the humanized regimen was noted for strains with higher MIC values and defined Cyp51 mutations. The ratio of posaconazole free-drug area under the concentration-time curve to the MIC (AUC/MIC) associated with a stasis endpoint in the mouse model was then utilized with in vitro surveillance data and a human posaconazole population pharmacokinetic model to perform simulations and PK/PD target attainment analyses. The results of these analyses demonstrated >90% probability of PK/PD target attainment for A. fumigatus strains with MICs of ≤0.5 mg/L, thus supporting this susceptible breakpoint threshold.

The catalytic activity of β-lactamases, particularly class A enzymes like KPC-2, is central to β-lactam antibiotic resistance. While phosphate buffers are widely used in enzymatic assays due to their physiological relevance, their potential to interfere with enzyme function remains underappreciated. Here, we demonstrate that phosphate acts as a competitive inhibitor of KPC-2 β-lactamase, significantly reducing catalytic efficiency in a concentration-dependent manner. This inhibition is mediated through interactions with threonine 237, as substitution with glycine (T237G) abolishes the inhibitory effect. In contrast, CTX-M-14 and TEM-1, which possess serine and alanine at the same position, respectively, exhibit minimal phosphate sensitivity, underscoring enzyme-specific buffer effects. Structural and kinetic analyses indicate that phosphate binding at the active site primarily impairs substrate affinity and, in some cases, also reduces catalytic turnover. These findings highlight the potential impact of buffer selection in β-lactamase assays and suggest that phosphate-mediated inhibition may lead to underestimation of enzyme activity and inhibitor potency, particularly in studies involving KPC-2. Standardizing assay conditions is essential for accurate evaluation of β-lactamase function and resistance mechanisms.

We describe, for the first time, the presence and characterization of CTX-M-15 and OXA-9 in two Haemophilus influenzae strains: PTHi-14525 (CTX-M-15) from Portugal and HUB-HI042681 (OXA-9) from Spain. Multidrug-resistant PTHi-14525 carried bla_CTX-M-15 (two copies) and bla_TEM-1 in an ICEHpaHUB5-like element. HUB-HI042681, resistant to β-lactams and aminoglycosides, carried a novel ICEHinHUB1. These findings highlight the genomic plasticity and expanded resistome of H. influenzae, raising concerns about treatment and emphasizing the need for continuous genomic surveillance.