Antimicrobial Agents and Chemotherapy最新文献

Doravirine (DOR) is a novel antiretroviral agent with a favorable resistance profile and high tolerability. However, evidence is limited on DOR among elderly people living with HIV (PLWH) and whether it might modulate chronic inflammation. We aimed to investigate the efficacy, safety, and tolerability of DOR as a switching strategy among elderly PLWH and its impact on chronic inflammation in a real-life setting. We recruited a cohort of ART-experienced PLWH undergoing a therapeutic switch to a DOR-based regimen under virologic control (defined as HIV-RNA <200 copies/mL), regardless of the previous ART regimen. The primary objective was the evaluation of the rate of virologic control at 48 weeks post-switch. Secondary objectives included analyzing immune and metabolic outcomes. Plasmatic hs-CRP, IL-6, and D-dimer levels were measured as chronic inflammation markers. Overall, 150 PLWH were screened, and 147 were enrolled into the study. A total of 134 PLWH completed the follow-up. The rate of virological control was 96.1% (122/134; CIs: 91.0%-98.7%) in the per-protocol analysis. After 48 weeks from the switch, we recorded significant reductions in serum fasting glycemia (P 0.019), triglycerides (P 0.024), and total cholesterol/HDL ratio (P 0.017); no clinically significant differences were detected in the body weight and BMI, as long as in immune, hepatic, and renal profiles. A significant reduction in IL-6 (P 0.019) and hs-CRP (P 0.019) was observed. DOR is an effective and safe treatment choice for elderly PLWH. The intriguing modulatory effect of DOR-based regimens on chronic systemic inflammation deserves further investigation.

Candida auris is an emerging pathogenic fungus that is highly resistant to existing antifungal drugs. Manogepix is a novel antifungal agent that exerts antifungal activity by inhibiting glycosylphosphatidylinositol anchor biosynthesis. Although the mechanisms of resistance of Candida species to manogepix have been reported previously, those of C. auris are yet to be studied. To investigate the resistance mechanisms of C. auris, we exposed a clinical isolate (clade I) to manogepix in vitro and generated strains with reduced susceptibility to manogepix. A search for gain-of-function mutations that upregulate efflux pump expression confirmed the presence of the D865N amino acid mutation in TAC1b. We used the clustered regularly interspaced short palindromic repeats-Cas9 system to create a recovery strain (N865D) in which only this single nucleotide mutation was returned to the wild-type sequence. We generated a mutant strain by introducing only the D865N mutation into the parent strain and a different clade strain (clade III). The D865N mutant strains were clearly less susceptible to manogepix than the parental strains and exhibited high CDR1 expression. Moreover, we generated a strain deficient in CDR1 and confirmed that this strain had significantly increased susceptibility to manogepix. Thus, the present study demonstrated that the TAC1b mutation in C. auris upregulates CDR1 expression and decreases its susceptibility to manogepix.

Bacteriophages are an increasingly attractive option for the treatment of antibiotic-resistant infections, but their efficacy is difficult to discern due to the confounding effects of antibiotics. Phages are generally delivered in conjunction with antibiotics, and thus, when patients improve, it is unclear whether the phages, antibiotics, or both are responsible. This question is particularly relevant for enterococcus infections, as limited data suggest phages might restore antibiotic efficacy against resistant strains. Enterococci can develop high-level resistance to vancomycin, a primary treatment. We assessed clinical and laboratory isolates of Enterococcus faecium and Enterococcus faecalis to determine whether we could observe synergistic interactions between phages and antibiotics. We identified synergy between multiple phages and antibiotics including linezolid, ampicillin, and vancomycin. Notably, antibiotic susceptibility did not predict synergistic interactions with phages. Vancomycin-resistant isolates (n = 6) were eradicated by the vancomycin-phage combination as effectively as vancomycin-susceptible isolates (n = 2). Transcriptome analysis revealed significant gene expression changes under antibiotic-phage conditions, especially for linezolid and vancomycin, with upregulated genes involved in nucleotide and protein biosynthesis and downregulated stress response and prophage-related genes. While our results do not conclusively determine the mechanism of the observed synergistic interactions between antibiotics and phages, they do confirm and build upon previous research that observed these synergistic interactions. Our work highlights how using phages can restore the effectiveness of vancomycin against resistant isolates. This finding provides a promising, although unexpected, strategy for moving forward with phage treatments for vancomycin-resistant Enterococcus infections.

A Stenotrophomonas maltophilia strain positive for the bla_VIM-1 metallo-beta-lactamase gene and resistant to trimethoprim-sulfamethoxazole was unexpectedly isolated from a surveillance rectal swab. The characterization of the strain revealed carriage of a 91 kb integrative and conjugative element (ICE) harboring several resistance determinants [sul1, bla_VIM-1, aac(6')-Ib, aac(6')-31, qacE∆1, cld, and merEDAPTR], closely related with a group of clc-type ICEs widespread among Pseudomonas aeruginosa and other pseudomonads. Results highlighted the possible spreading of similar elements to S. maltophilia, mediating the acquisition of relevant resistances.

A major challenge in tuberculosis (TB) therapeutics is that antibiotic exposure leads to changes in the physiology of M. tuberculosis (Mtb), which may enable the pathogen to withstand treatment. While antibiotic-treated Mtb has been evaluated in in vitro experiments, it is unclear if and how long-term in vivo treatment with diverse antibiotics with varying treatment-shortening activity (sterilizing activity) affects Mtb physiologic processes differently. Here, we used SEARCH-TB, a pathogen-targeted RNA-sequencing platform, to characterize the Mtb transcriptome in the BALB/c high-dose aerosol infection mouse model following 4 weeks of treatment with three sterilizing and three non-sterilizing antibiotics. Certain transcriptional changes were shared among most antibiotics, including decreased expression of genes associated with protein synthesis and metabolism and the induction of certain genes associated with stress responses. However, the magnitude of this shared response differed between antibiotics. Sterilizing antibiotics rifampin, pyrazinamide, and bedaquiline generated a more quiescent Mtb state than did non-sterilizing antibiotics isoniazid, ethambutol, and streptomycin, as indicated by the decreased expression of genes associated with translation, transcription, secretion of immunogenic proteins, metabolism, and cell wall synthesis. Additionally, we identified distinguishing transcriptional effects specific to each antibiotic, indicating that different mechanisms of action induce distinct patterns in response to cellular injury. In addition to elucidating the Mtb physiologic changes associated with antibiotic stress, this study demonstrates the value of SEARCH-TB as a highly granular pharmacodynamic assay that reveals antibiotic effects that are not apparent based on culture alone.

Ceftobiprole was recently approved by the United States (US) Food and Drug Administration (FDA) for the treatment of adult patients with Staphylococcus aureus bacteremia, including right-side endocarditis, acute bacterial skin and skin structure infections, and community-acquired bacterial pneumonia in adults and pediatrics. Ceftobiprole is an advanced-generation cephalosporin approved in many countries for the treatment of adults with community-acquired pneumonia and hospital-acquired pneumonia, excluding ventilator-associated pneumonia. We evaluated the activities of ceftobiprole and comparators against methicillin-resistant S. aureus (MRSA) and multidrug-resistant (MDR) S. aureus clinical isolates. A total of 19,764 S. aureus isolates were collected from patients with various infection types at 37 US medical centers from 2016 to 2022. Susceptibility testing was performed by broth microdilution according to Clinical and Laboratory Standard Institutes (CLSI) standards. Isolates were categorized as MDR if they were nonsusceptible by CLSI criteria to ≥3 antimicrobials. Ceftobiprole was highly active against MRSA (n = 8,184; MIC_50/90, 1/2 mg/L; 99.3% susceptible [S]) and MDR (n = 2,789; MIC_50/90, 1/2 mg/L; 98.1%S) isolates and retained activity against 87.3% of ceftaroline-nonsusceptible isolates (n = 433; MIC_50/90, 2/4 mg/L). Ceftobiprole demonstrated greater susceptibility rates than ceftaroline against all resistant subsets. Ceftobiprole was highly active against isolates nonsusceptible to clindamycin (98.0%S), daptomycin (100.0%S), doxycycline (98.2%S), erythromycin (99.5%S), gentamicin (98.1%S), levofloxacin (99.1%S), tetracycline (99.1%S), tigecycline (100.0%S), and trimethoprim-sulfamethoxazole (99.4%S) and isolates with decreased susceptibility to vancomycin (98.3%S).

The development of new and improved antiretroviral therapies that allow for alternative dosing schedules is needed for people living with HIV-1. Islatravir is a deoxyadenosine analog in development for the treatment of HIV-1 that suppresses HIV-1 replication via multiple mechanisms of action, including reverse transcriptase translocation inhibition and delayed chain termination. Islatravir is differentiated from other HIV-1 antiretrovirals by its high potency, long t_½, broad tissue distribution, and favorable drug resistance profile. A comprehensive evaluation was performed to provide data on the mass balance, absorption, metabolism, and excretion of islatravir through studies in nonclinical species, and in adults without HIV-1 infection, using radiolabeled islatravir. Islatravir was well absorbed in both nonclinical species and humans following oral administration. The elimination of islatravir occurs primarily by a combination of oxidative deamination to 4'-ethynyl-2-fluoro-2'-deoxyinosine and renal excretion of unchanged islatravir. Islatravir and 4'-ethynyl-2-fluoro-2'-deoxyinosine are the major circulating drug components in all species assessed. Islatravir is readily taken up into cells with efficient phosphorylation to the mono-, di-, and triphosphate forms. The pharmacologically active islatravir triphosphate is the most abundant intracellular phosphorylated species, as shown by the results of ex vivo studies. This characterization of the absorption, metabolism, and elimination of islatravir in humans and nonclinical species supports its further development for the treatment of HIV-1.

This comparative study aimed at qualifying a broth microdilution (BMD) assay for phenotypic drug susceptibility testing (pDST) of Mycobacterium tuberculosis complex (MTBC) strains for implementation in a routine DST workflow. The assay was developed based on the EUCAST (European Committee on Antimicrobial Susceptibility Testing) reference protocol for determination of the minimum inhibitory concentration (MIC) of 14 anti-tuberculous drugs (isoniazid [INH], rifampicin [RIF], ethambutol [EMB], amikacin [AMI], moxifloxacin [MFX], levofloxacin [LFX], bedaquiline [BDQ], clofazimine [CFZ], delamanid [DLM], pretomanid [PA], para-aminosalicylic acid [PAS], linezolid [LZD], ethionamide [ETH], and cycloserine [CS]). Forty MTBC strains with various drug resistance profiles were tested to determine the agreement between MIC results and genotypic drug susceptibility testing (gDST) results derived from whole-genome sequencing (WGS). The agreement between the BMD and gDST results was solid for the majority of the drugs (average agreement 98%, range 90%-100%), including key drugs such as INH, RIF, MFX, LFX, BDQ, DLM, and PA. Ten discrepancies were identified (corresponding to 1.8% of the total number of MIC determinations) and most (8/10) were characterized by MICs equal or close to the potential critical concentration (pCC) applied in the BMD assay. Importantly, the assay can be adjusted to new drug recommendations and concentrations, tailored to local needs. We conclude that the BMD assay provides reliable results, and its implementation in our MTBC routine workflow will produce valuable data that improve our understanding and management of MTBC drug resistance.

Mycobacterium abscessus (Mab) presents significant clinical challenges. This study evaluated the synergistic effects of a β-lactam and β-lactamase inhibitor combination against Mab and explored the underlying mechanisms. Synergy was assessed through MIC tests and time-kill studies, and binding affinities of nine β-lactams and BLIs to eight target receptors (L,D-transpeptidases [LDT] 1-5, D,D-carboxypeptidase, penicillin-binding protein [PBP] B, and PBP-lipo) were assessed using mass spectrometry and kinetic studies. Thermal stability and morphological changes were determined. Imipenem demonstrated high binding affinity to LDTs and PBPs, with extremely low inhibition constants (K_i,app; ≤0.002 mg/L for LDT1-2, ≤0.6 mg/L for PBPs), while cephalosporins, sulopenem, tebipenem, and amoxicillin exhibited moderate to low binding affinity. Durlobactam inactivated Bla_Mab and LDT/PBPs more potently than avibactam. The K_i,apps of durlobactam for PBP B, PBP-lipo, and LDT2 were below clinically achievable unbound concentrations, while avibactam's K_i,app for LDT/PBPs exceeded the clinical concentrations. Single β-lactam treatments resulted in minimal killing (~1 log₁₀ reduction). Although avibactam yielded no effect, combinations with avibactam showed a significant reduction (~4 log₁₀ CFU/mL). Durlobactam alone showed ~2 log₁₀ reduction, and when combined with imipenem or two β-lactams, durlobactam achieved near-eradication of Mab, surpassing the current therapy (amikacin + clarithromycin + imipenem/cefoxitin). Inactivation of PBP-lipo by sulopenem, imipenem, durlobactam, and amoxicillin (with avibactam) led to morphological changes, showing filaments. This study demonstrates the mechanistic basis of combinations therapy, particularly imipenem + durlobactam, in overcoming β-lactam resistance in Mab.

The reliability of ceftriaxone for inferring susceptibility to higher-generation oral cephalosporins is unknown. Overall, ceftriaxone susceptibility predicted susceptibility to cefuroxime (89%), cefdinir (86%), cefpodoxime (90%), and cefixime (94%) based on disk diffusion results for 409 consecutive Enterobacterales bloodstream isolates from unique patients. Susceptibility percentages to the four oral cephalosporins ranged from 92% to 99% when limited to Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, or Proteus mirabilis isolates susceptible to ceftriaxone.