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Objective: Hypermutable Pseudomonas aeruginosa strains are highly prevalent in chronic lung infections of patients with cystic fibrosis (CF). Acute exacerbations of these infections have limited treatment options. This study aimed to investigate inhaled aztreonam and tobramycin against clinical hypermutable P. aeruginosa strains using the CDC dynamic in vitro biofilm reactor (CBR), mechanism-based mathematical modelling (MBM) and genomic studies.
Methods: Two CF multidrug-resistant strains were investigated in a 168 h CBR (n = 2 biological replicates). Regimens were inhaled aztreonam (75 mg 8-hourly) and tobramycin (300 mg 12-hourly) in monotherapies and combination. The simulated pharmacokinetic profiles of aztreonam and tobramycin (t = 3 h) were based on published lung fluid concentrations in patients with CF. Total viable and resistant counts were determined for planktonic and biofilm bacteria. MBM of total and resistant bacterial counts and whole genome sequencing were completed.
Results: Both isolates showed reproducible bacterial regrowth and resistance amplification for the monotherapies by 168 h. The combination performed synergistically, with minimal resistant subpopulations compared to the respective monotherapies at 168 h. Mechanistic synergy appropriately described the antibacterial effects of the combination regimen in the MBM. Genomic analysis of colonies recovered from monotherapy regimens indicated noncanonical resistance mechanisms were likely responsible for treatment failure.
Conclusion: The combination of aztreonam and tobramycin was required to suppress the regrowth and resistance of planktonic and biofilm bacteria in all biological replicates of both hypermutable multidrug-resistant P. aeruginosa CF isolates. The developed MBM could be utilised for future investigations of this promising inhaled combination.
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http://dx.doi.org/10.1016/j.ijantimicag.2024.107161 | DOI Listing |
Lung India
September 2025
Department of Pulmonary Medicine, Apollo Hospitals, Chennai, Tamil Nadu, India.
Bronchiectasis is a chronic airway disease with recurrent exacerbations and hospitalisations. No inhaled antibiotic has shown consistently beneficial effects in trials. This review analyses the evidence on inhaled antibiotics in non-cystic fibrosis bronchiectasis (NCFB), identifies patient traits for their use, and highlights research gaps.
View Article and Find Full Text PDFCefepime-taniborbactam (FEP-TAN) and meropenem-xeruborbactam (MEM-XER) are β-lactam-β-lactamase inhibitor (BL-BLI) combinations currently in development and both projected to treat metallo-β-lactamase (MBL)-producing Gram-negative pathogens. Among Gram-negative pathogens, the low permeability of the outer membrane of poses unique challenges to drug discovery in general and to BL-BLIs in particular. This study set out to augment β-lactam antibiotic potency by enhancing outer membrane permeability of using novel amphiphilic aminoglycoside-based outer membrane permeabilizers.
View Article and Find Full Text PDFMicrob Pathog
September 2025
Laboratory of Biochemistry, Environment and Agri-food, Faculty of Sciences and Technology Mohammedia, University Hassan II, Casablanca, Morocco.
Introduction: The study aimed to determine the occurrence of genes encoding antibacterial resistance in Escherichia coli (E. coli) isolates recovered from poultry products.
Method: ology: Antibiotic susceptibility was tested using the disc diffusion method, and then resistance genes and virulence profiles were determined by whole-genome analysis.
J Clin Microbiol
August 2025
Vanderbilt Medical Center University, Nashville, Tennessee, USA.
The purpose of this study was to establish tentative Clinical and Laboratory Standards Institute (CLSI) M45 MIC and disk diffusion (DD) breakpoints (BPs) for other than (POPA). Mechanisms of antimicrobial resistance (AMR) and the modified carbapenem inactivation method (mCIM) to detect carbapenemase production were also evaluated. MIC data from and POPA from 2013 to 2022 were evaluated to compare the MIC distributions and modal MICs relative to the CLSI M100 BPs.
View Article and Find Full Text PDFPak J Pharm Sci
June 2025
Department of Respiratory and Critical Care Medicine, Second Medical Center of Chinese PLA General Hospital, 28 Fuxing Road, Haidian District, Beijing, China.
This study aimed to analyze the characteristics and prognostic factors of multi-drug resistant Pseudomonas aeruginosa (MDRPA) pulmonary infection in elderly patients. Clinical data from 118 elderly patients diagnosed with MDRPA infections at Chinese PLA General Hospital were retrospectively reviewed. The 118 cases were mainly from ICU (51 cases, 43.
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