Antimicrobial Agents and Chemotherapy最新文献

Despite guideline-based therapy, some patients with Mycobacterium avium complex pulmonary disease (MAC-PD) experience treatment failure. We analyzed the clinical courses of 271 patients with treatment-refractory MAC-PD who discontinued therapy after at least 12 months. Patients were categorized into two groups-the retreatment group, who resumed antibiotics due to clinical or radiological deterioration, and the stable group, who did not require antibiotics. Of the study patients, 138 (51%) were in the retreatment group, whereas 133 (49%) were in the stable group. In the multivariate analysis models, an elevated erythrocyte sedimentation rate (adjusted hazard ratio [aHR] =1.01), the presence of a cavity (aHR = 1.75), and the number of lobes affected by bronchiectasis (aHR = 1.21) were associated with the need for retreatment. Our data indicated that approximately 50% of the patients with refractory MAC-PD who discontinued antibiotics eventually required retreatment, which was influenced by the extent of lung destruction or inflammation. These findings can aid in determining treatment strategies for patients with refractory diseases.

Nontuberculous mycobacteria (NTM) infections are extremely difficult to treat due to a natural resistance to many antimicrobials. TBAJ-587 is a novel diarylquinoline, which shows higher anti-tuberculosis activity, lower lipophilicity, and weaker inhibition of hERG channels than bedaquiline (BDQ). The susceptibilities of 11 NTM reference strains and 194 clinical Mycobacterium abscessus isolates to TBAJ-587 were determined by the broth microdilution assay. The activity of TBAJ-587 toward the growth of M. abscessus in macrophages was also evaluated. Minimum bactericidal concentration and time-kill kinetic assays were conducted to distinguish between the bactericidal and bacteriostatic activities of TBAJ-587. The synergy between TBAJ-587 and eight clinically important antibiotics was determined using a checkerboard assay. TBAJ-587 was highly effective against M. abscessus by targeting its F-ATP synthase c chain. The antimicrobial activities of TBAJ-587 and BDQ toward intracellular M. abscessus were comparable. The in vivo activities of TBAJ-587 and BDQ in an immunocompromised mouse model were also comparable. TBAJ-587 expressed bactericidal activity and was compatible with eight anti-NTM drugs commonly used in clinical practice; no antagonism was discovered. As such, TBAJ-587 represents a potential candidate for the treatment of NTM infections.

Candida auris is a pathogenic yeast of particular concern because of its ability to cause nosocomial outbreaks of invasive candidiasis (IC) and to develop resistance to all current antifungal drug classes. Most C. auris clinical isolates are resistant to fluconazole, an azole drug that is used for the treatment of IC. Azole resistance may arise from diverse mechanisms, such as mutations of the target gene (ERG11) or upregulation of efflux pumps via gain of function mutations of the transcription factors TAC1 and/or MRR1. To explore novel mechanisms of azole resistance in C. auris, we applied an in vitro evolutionary protocol to induce azole resistance in a TAC1A/TAC1B/MRR1 triple-deletion strain. Azole-resistant isolates without ERG11 mutations were further analyzed. In addition to a whole chromosome aneuploidy of chromosome 5, amino acid substitutions were recovered in the transcription factor Upc2 (N592S, L499F), the ubiquitin ligase complex consisting of Ubr2 (P708T, H1275P) and Mub1 (Y765*), and the mitochondrial protein Mrs7 (D293H). Genetic introduction of these mutations in an azole-susceptible wild-type C. auris isolate of clade IV resulted in significantly decreased azole susceptibility. Real-time reverse transcription PCR analyses were performed to assess the impact of these mutations on the expression of genes involved in azole resistance, such as ERG11, the efflux pumps CDR1 and MDR1 or the transcription factor RPN4. In conclusion, this work provides further insights in the complex and multiple pathways of azole resistance of C. auris. Further analyses would be warranted to assess their respective role in azole resistance of clinical isolates.

Acinetobacter baumannii is globally recognized as a multi-drug-resistant pathogen of critical concern due to its capacity for horizontal gene transfer and resistance to antibiotics. Phylogenetically diverse Acinetobacter species mediate human infection, including many considered as important emerging pathogens. While globally recognized as a pathogen of concern, pathogenesis mechanisms are poorly understood. P-type type IV secretion systems (T4SSs) represent important drivers of pathogen evolution, responsible for horizontal gene transfer and secretion of proteins that mediate host-pathogen interactions, contributing to pathogen survival, antibiotic resistance, virulence, and biofilm formation. Genes encoding a P-type T4SS were previously identified on plasmids harboring the carbapenemase gene bla_NDM-1 in several clinically problematic Acinetobacter; however, their prevalence among the genus, geographical distribution, the conservation of T4SS proteins, and full capacity for resistance genes remain unclear. Using systematic analyses, we show that these plasmids belong to a group of 53 P-type T4SS-encoding plasmids in 20 established Acinetobacter species, the majority of clinical relevance, including diverse A. baumannii sequence types and one strain of Providencia rettgeri. The strains were globally distributed in 14 countries spanning five continents, and the conjugative operon's T4SS proteins were highly conserved in most plasmids. A high proportion of plasmids harbored resistance genes, with 17 different genes spanning seven drug classes. Collectively, this demonstrates that P-type T4SS-encoding plasmids are more widespread among the Acinetobacter genus than previously anticipated, including strains of both clinical and environmental importance. This research provides insight into the spread of resistance genes among Acinetobacter and highlights a group of plasmids of importance for future surveillance.

Cabotegravir intramuscular gluteal injection is approved for HIV treatment (with rilpivirine) and prevention. Thigh muscle is a potential alternative injection site. We aim to characterize cabotegravir pharmacokinetics and its association with demographics following intramuscular thigh injection in comparison with gluteal injection using population pharmacokinetic (PPK) analysis. Fourteen HIV-negative participants received 600 mg single thigh injection in phase 1 study 208832 and 118 participants with HIV received thigh injections 400 mg monthly 4× or 600 mg once-every-2-months 2× after ≥3 years of gluteal injections in phase 3b study ATLAS-2M provided 1,249 cabotegravir concentrations from 366 thigh injections and 1,998 concentrations from 1,618 gluteal injections. The established gluteal PPK model was modified by adding thigh injection compartment and fit to pharmacokinetic data following both gluteal and thigh injections, enabling within-person comparison in ATLAS-2M. Gluteal parameters were fixed. Similar to the gluteal absorption rate constant (KA_gluteal), the thigh absorption rate constant (KA_thigh) was slower in females than males and in participants with higher BMI. KA_thigh was strongly correlated with KA_gluteal (correlation coefficient 0.766), best described by the additive linear relationship KA_thigh = KA_gluteal + 0.0002527 h^-1. Terminal half-life of thigh injection was 26% (male) and 39% (female) shorter than gluteal injection. Relative bioavailability of thigh to gluteal was estimated to be 89.9%. The impact of covariates on cabotegravir exposure following thigh injections was ≤35%. In conclusion, cabotegravir absorption following thigh injection was correlated with, faster than, and 10% less bioavailable than gluteal injection, and correlated with sex and BMI. The cabotegravir thigh PPK model can inform dosing strategies and future study design.

Artemisinin partial resistance (ART-R) has emerged in eastern Africa, necessitating regular surveillance of susceptibility of Plasmodium falciparum to artemisinins. The microscopy-based ring-stage survival assay (RSA) provides a laboratory correlate of ART-R but is limited by low throughput and subjectivity of microscopic counts of viable parasites. The extended recovery ring-stage survival assay (eRRSA) replaces microscopy with efficient quantitative PCR (qPCR) readouts but has been studied only with culture-adapted P. falciparum clones. We measured susceptibility to dihydroartemisinin (DHA) after a 6-h incubation with 700-nM DHA, followed by culture without drug, by comparing survival with that of untreated controls by microscopy (the RSA) or qPCR (the eRRSA) and also performed standard growth inhibition (half-maximal inhibitory concentration [IC₅₀]) assays for 122 P. falciparum isolates freshly collected in eastern and northern Uganda from March to July 2022. The median values for RSA survival, eRRSA fold change, and DHA IC₅₀ were 3.0%, 46.2, and 3.2 nM, respectively. RSA percent survival and eRRSA fold changes correlated strongly (Spearman correlation coefficient [r_s] = -0.7411, P < 0.0001), with modest associations between the presence of validated P. falciparum Kelch13 ART-R mutations (C469Y or A675V) and RSA (median survival 2.6% for wild type [WT] vs 4.1% for mutant, P = 0.01), or eRRSA (median fold change 63.4 for WT vs 30.9 for mutant, P = 0.003) results. Significant correlations were also observed between DHA IC₅₀ values and both RSA percent survival (r_s = 0.4235, P < 0.0001) and eRRSA fold changes (r_s = -0.4116, P < 0.0001). The eRRSA is a scalable alternative for phenotyping fresh P. falciparum isolates, providing similar results with improved throughput.

Thiamine is metabolized into thiamine pyrophosphate (TPP), an essential enzyme cofactor. Previous work has shown that oxythiamine, a thiamine analog, is metabolized by thiamine pyrophosphokinase (TPK) into oxythiamine pyrophosphate within the malaria parasite Plasmodium falciparum and then inhibits TPP-dependent enzymes, killing the parasite in vitro and in vivo. To identify a more potent antiplasmodial thiamine analog, 11 commercially available compounds were tested against P. falciparum and P. knowlesi. Five active compounds were identified, but only N3-pyridyl thiamine (N3PT), a potent transketolase inhibitor and candidate anticancer lead compound, was found to suppress P. falciparum proliferation with an IC₅₀ value 10-fold lower than that of oxythiamine. N3PT was active against P. knowlesi and was >17 times less toxic to human fibroblasts, as compared to oxythiamine. Increasing the extracellular thiamine concentration reduced the antiplasmodial activity of N3PT, consistent with N3PT competing with thiamine/TPP. A transgenic P. falciparum line overexpressing TPK was found to be hypersensitized to N3PT. Docking studies showed an almost identical binding mode in TPK between thiamine and N3PT. Furthermore, we show that [³H]thiamine accumulation, resulting from a combination of transport and metabolism, in isolated parasites is reduced by N3PT. Treatment of P. berghei-infected mice with 200 mg/kg/day N3PT reduced their parasitemia, prolonged their time to malaria symptoms, and appeared to be non-toxic to mice. Collectively, our studies are consistent with N3PT competing with thiamine for TPK binding and inhibiting parasite proliferation by reducing TPP production, and/or being converted into a TPP antimetabolite that inhibits TPP-dependent enzymes.

The rapid rise of multidrug resistance (MDR) among Gram-negative bacteria has accelerated the development of novel therapies. Ceftazidime-avibactam (CZA) is a novel β-lactam/β-lactamase inhibitor recently approved for the treatment of limited infectious diseases. Here, we describe a novel CMY variant, CMY-192, that confers high-level resistance to CZA. This gene was detected in a clinical MDR Escherichia coli strain (Ec73552) isolated from an outpatient with a community-acquired urinary tract infection who had not received prior CZA treatment. Ec73552 was typed as O101:H9-ST10, a high-risk clone associated with human and animal diseases. Ec73552 was able to colonize the bladder in a mouse model, suggesting that this strain was uropathogenic. CMY-192 shared the highest amino acid identity (98.95%) with CMY-172 and conferred at least a 32-fold increase in CZA MIC (from ≤0.125/4 to 8/4 mg/L) when cloned into a CZA-susceptible E. coli DH5α strain. Knockout of CMY-192 in Ec73552 resulted in a 256-fold reduction in CZA MIC (from 64/4 to 0.25/4 mg/L). CMY-192 was encoded on an IncB/O/K/Z-type plasmid (pCMY192). Conjugation assays confirmed that pCMY192 was self-transmissible, resulting in a 256-fold increase in the CZA MIC of the recipient. Notably, pCMY192 cured in Ec73552 did not confer a growth advantage, while the conjugant exhibited reduced biomass and growth rate, indicating that fitness costs imposed by pCMY192 may have been compensated in Ec73552. Our findings highlight the importance of continuous monitoring of CZA susceptibility to prevent the spread of resistance in clinical settings.

Fluoroquinolones (FQs) are considered the most effective antimicrobial treatment for Gram-negative prosthetic joint infection (GN-PJI). Alternatives are needed due to increasing FQ resistance and side effects. We aimed to compare different targeted antimicrobial strategies for GN-PJI managed by debridement, antibiotics, and implant retention (DAIR) or one-stage revision surgery (1SR) and to review the literature of oral treatment options for GN-PJI. In this prospective, multicenter, registry-based study, all consecutive patients with a PJI caused by a Gram-negative microorganism (including mixed infections with Gram-positive microorganisms), managed with DAIR or 1SR from 2015 to 2020, were included. Minimum follow-up was 1 year. Patients underwent targeted therapy with oral FQ, oral cotrimoxazole, or intravenous or oral β-lactams. Survival analysis was performed with use of Kaplan-Meier and Cox proportional hazards models to identify factors potentially associated with treatment failure. Seventy-four patients who received either FQ (n = 47, 64%), cotrimoxazole (n = 13, 18%), or β-lactams (n = 14, 18%) were included. Surgical strategy consisted of DAIR (n = 72) or 1SR (n = 2). Median follow-up was 449 days (interquartile range 89-738 days). Failure free survival did not differ between the FQ (72%) and cotrimoxazole (92%) groups (log rank, P = 0.13). This outcome did not change when excluding all pseudomonal PJI in the FQ group. Cotrimoxazole is a potential effective targeted antimicrobial therapy for patients with GN-PJI. A randomized controlled trial is needed to confirm the findings of this study.