International Journal of Antimicrobial Agents最新文献

Introduction: The evolution of antimicrobial resistance (AMR) in Staphylococcus aureus (S. aureus) involves complex genotype-phenotype interactions of multiple genetic determinants acting independently.

Objectives: In this study, we aimed to accurately predict AMR from genomic sequences and uncover the complex genetic interactions underlying its mechanisms, focusing on interpretability and mechanistic insights.

Methods: We propose a framework that elucidates antibiotic resistance by linking the genomic context with underlying gene interactions, combining a reference-agnostic gene-context 22-mer (gkmer) representation, a two-step random forest pipeline (RF1 screening/mapping; RF2 gene-level modeling), co-information-based synergy networks, and protein-structure mapping.

Results: Using genomic sequences from 4,569 S. aureus strains, we successfully predicted resistance to 12 antibiotics and examined the genetic interaction networks for penicillin, ciprofloxacin, and erythromycin in detail. On the held-out 20% test set, RF2 achieved an area under the receiver operating characteristic curve (AUC) of 0.83-1.00 (median 0.90) and an F1 score of 0.58-0.99 (median 0.76); comparable performance was observed for RF1. External validation on an independent dataset including 1,011 S. aureus isolates revealed strong generalization for ciprofloxacin, erythromycin, and penicillin (AUC > 0.95; F1 > 0.97), while highlighting reduced performance for clindamycin and tetracycline, and failure for gentamicin and trimethoprim, thereby delineating the scope and limits of the model and its applicability. Network analysis revealed distinct structural patterns of gene cooperation, highlighting key hubs and community structures consistent with known resistance pathways.

Conclusion: Our findings indicate that antibiotic resistance in S. aureus involves distinct genetic network architectures depending on the antibiotic, highlighting the diverse regulatory pathways bacteria employ to acquire resistance. This discovery-oriented framework prioritizes interpretable determinants and generates testable mechanistic hypotheses, with prospective standardized evaluations aimed at assessing its translatability to clinical settings.

The introduction of doxycycline post-exposure prophylaxis (doxy-PEP) as a strategy to reduce the risk of bacterial sexually transmitted infections has raised concerns about the potential for rapid selection of tetracycline resistance and the emergence of ceftriaxone-resistant strains. This study aimed to develop a molecular surveillance method to monitor antimicrobial resistance (AMR) in Neisseria gonorrhoeae (NG) during doxy-PEP implementation. We developed a high-resolution melting (HRM) analysis-based molecular assay, termed HRM-doxyPEP, to enhance surveillance of NG AMR. Validation was conducted with strains of known susceptibility profiles, and further evaluation was performed on clinical samples, comparing HRM results with qPCR, whole-genome sequencing and PCR-sequencing. The HRM-doxyPEP assay demonstrated high analytical specificity and a detection limit of 20 copies/reaction, enabling the detection of low levels of target DNA in clinical samples. Validation with strains of known susceptibility profiles showed 84% consistency with AST results. Clinical sample testing revealed 100% sensitivity and specificity for identifying NG infection, tracking ceftriaxone-resistant FC428-like strains, and detecting tetM associated with tetracycline resistance. The HRM-doxyPEP assay offers an accurate, affordable, and scalable tool for enhanced molecular surveillance of AMR in NG during doxy-PEP implementation.

Background: Carbapenemase-producing Klebsiella pneumoniae (CP-Kp) poses a significant global health threat due to its limited treatment options and increasing resistance. Fosfomycin (FOF) has regained interest, particularly in combination therapies. This study aimed to evaluate the in vitro synergy of FOF with meropenem (MEM) and polymyxin in CP-Kp bloodstream infections (BSI) and to investigate clinical outcomes.

Methods: Fifty-two patients with CP-Kp BSI who received FOF-based combination therapy (FOF-C) for ≥72 hours were evaluated retrospectively for clinical outcomes. MICs were determined on stored isolates: FOF by agar dilution (AD) and broth microdilution (BMD), MEM and COL by BMD. In vitro synergy testing of FOF with MEM and COL was performed using the checkerboard (CB) method. Data were analyzed using logistic regression.

Results: Among 50 isolates, the FOF AD MIC_50/90 were 64/>128 μg/mL. Positive in vitro interactions (synergistic or additive) were observed in 43.5% of isolates for both FOF+MEM and FOF+COL, with no antagonism. The clinical and microbiological response rates were 61.5% and 80.5%, 14- and 30-day mortality rates were 21.2% and 40.4%, respectively. Patients receiving at least one agent with in vitro positive interaction had higher clinical response, but the difference wasn't significant (73.7% vs. 52.2% p=0.153). In multivariable analysis, increased FOF AD MIC and Pitt bacteremia score (PBS) were associated with clinical nonresponse, while higher COL MIC and PBS predicted 30-day mortality.

Conclusion: FOF AD MIC value may have potential as a predictive marker for FOF-C treatment response in CP-Kp BSI and could aid in guiding combination therapy decisions. Larger, prospective studies using standardized synergy testing methods are needed.

Background: Ibuprofen is frequently co-administered with antibiotics for its analgesic effect when treating infections. In vitro studies have shown ibuprofen exhibits concentration-dependent inhibition of the organic anion transporters (OAT) 1 and OAT3 and therefore may reduce the clearance of β-lactams including flucloxacillin, in a similar manner to probenecid. We therefore aimed to evaluate the effect of ibuprofen on the pharmacokinetics (PK) of flucloxacillin in healthy volunteers.

Methods: Single site, PK study of 10 healthy adult volunteers. Over a three-day intervention period, participants received intravenous (IV) flucloxacillin 2000 mg twice daily with oral ibuprofen 400 mg twice daily on days 2 and 3. Total and unbound flucloxacillin plasma concentrations were collected at predefined time points. A population PK model was developed using a non-linear mixed effects modelling approach and ibuprofen assessed as a covariate in the final model.

Results: Ten participants with a median age of 24.4 years (range 18.8-54.5) and weight of 68.3 kilograms (range 50.5-85.7) were included. A median of 51.5 (range 34-52) samples were collected per participant. The final two-compartment model included saturable protein binding and allometric scaling of weight on clearance. Ibuprofen was not found to be a significant covariate on K_d (binding dissociation constant), B_max (maximum binding capacity) or clearance.

Conclusion: Orally administered ibuprofen had no measurable effect on plasma flucloxacillin PK in healthy adults. Given the lack of drug-drug interaction, there is no benefit to prescribe ibuprofen alongside flucloxacillin to increase flucloxacillin exposure.

Objectives: Cefiderocol (FDC) is a promising treatment for infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP), but emerging heteroresistance (HR) may compromise its clinical efficacy. This study aimed to elucidate the molecular mechanisms underlying FDC heteroresistance arising during in vivo evolution of CRKP. in vivo-evolved.

Methods: A total of 477 clinical CRKP isolates were analyzed. FDC-heteroresistant (FDC-HR) subpopulations emerging during in vivo evolution were characterized using population analysis profiling, antimicrobial susceptibility testing, quantitative PCR, plasmid copy number analysis, transcriptomics, whole-genome sequencing, molecular modeling, and CRISPR-Cas9-based functional validation.

Results: Among the 477 CRKP isolates, 376 (78.8%) belonged to ST11-KL64, 4 (0.84%) were non-susceptible to FDC, and 12 (2.52%) exhibited an FDC-HR phenotype. Resistant subpopulations showed approximately a twofold increase in bla_KPC-2 plasmid copy number with upregulated expression compared with susceptible counterparts. A G652A point mutation in mrcA was identified and predicted to impair FDC binding. Functional validation demonstrated that the mrcA mutation alone increased the FDC minimum inhibitory concentration (MIC), while its combination with bla_KPC-2 amplification elevated the MIC from 2 to 32 mg/L, fully recapitulating the clinical heteroresistance phenotype. In vivo evolution reduced virulence without affecting growth.

Conclusions: Amplification of bla_KPC-2 plasmid copy number together with the mrcA G652A mutation drives FDC-HR in CRKP during in vivo evolution. This mechanism may lead to underestimation of resistance by standard susceptibility testing and increase the risk of treatment failure.

Objective: We aimed to identify novel inhibitors against carbapenem-resistant Acinetobacter baumannii (CR-AB) derived from Streptomyces taklimakanensis sp. nov. TRM43335 and to evaluate their dual antibiofilm and anti-inflammatory mechanisms.

Methods: The TRM43335 extract yielded 3-indole carbaldehyde through bioactivity-guided isolation. Its antibiofilm activity was assessed using crystal violet, extracellular polymeric substances (EPS) quantification, motility, confocal laser scanning microscopy (CLSM), reverse transcription quantitative polymerase chain reaction (RT-qPCR) targeting ompA (outer-membrane protein A), bfmR (biofilm-associated regulator), and bap (biofilm-associated protein), and molecular docking. In vivo efficacy was evaluated in a murine pneumonia model by measuring bacterial burden, histology, and expression of inflammation-related proteins (Toll-like receptor 4 [TLR4], nuclear factor-κB [NF-κB], NOD-like receptor family pyrin domain-containing 3 [NLRP3], and mitogen-activated protein kinase [MAPK] pathway components) via western blotting.

Results: 3-Indole carbaldehyde significantly reduced CR-AB biofilm, suppressed EPS/extracellular proteins, and impaired swarming motility, with marked downregulation of biofilm genes. In mice, 3-indole carbaldehyde treatment decreased lung bacterial load, improved histopathology and inhibited expression of TLR4, NF-κB, NLRP3, and MAPK pathway components (including p38, extracellular signal-regulated kinase 2 [ERK2], c-Jun N-terminal kinase [JNK], tumor necrosis factor receptor-associated factor 6 [TRAF6], and tumor necrosis factor alpha [TNF-α]), indicating suppression of inflammasome and MAPK signaling.

Conclusion: 3-indole carbaldehyde simultaneously inhibits CR-AB biofilm formation and attenuates pulmonary inflammation. Thus, it represents a novel dual-action therapeutic strategy that addresses the key limitations of single-target antibiotics such as meropenem. Coupled with a favorable safety profile, it is a highly promising candidate for treating drug-resistant CR-AB infections.