In:
Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 61, No. 12 ( 2017-12)
Abstract:
FosA proteins confer fosfomycin resistance to Gram-negative pathogens via glutathione-mediated modification of the antibiotic. In this study, we assessed whether inhibition of FosA by sodium phosphonoformate (PPF) (foscarnet), a clinically approved antiviral agent, would reverse fosfomycin resistance in representative Gram-negative pathogens. The inhibitory activity of PPF against purified recombinant FosA from Escherichia coli (FosA3), Klebsiella pneumoniae (FosA KP ), Enterobacter cloacae (FosA EC ), and Pseudomonas aeruginosa (FosA PA ) was determined by steady-state kinetic measurements. The antibacterial activity of PPF against FosA in clinical strains of these species was evaluated by susceptibility testing and time-kill assays. PPF increased the Michaelis constant ( K m ) for fosfomycin in a dose-dependent manner, without affecting the maximum rate ( V max ) of the reaction, for all four FosA enzymes tested, indicating a competitive mechanism of inhibition. Inhibitory constant ( K i ) values were 22.6, 35.8, 24.4, and 56.3 μM for FosA KP , FosA EC , FosA PA , and FosA3, respectively. Addition of clinically achievable concentrations of PPF (∼667 μM) reduced the fosfomycin MICs by ≥4-fold among 52% of the K. pneumoniae , E. cloacae , and P. aeruginosa clinical strains tested and led to a bacteriostatic or bactericidal effect in time-kill assays among representative strains. PPF inhibits FosA activity across Gram-negative species and can potentiate fosfomycin activity against the majority of strains with chromosomally encoded fosA . These data suggest that PPF may be repurposed as an adjuvant for fosfomycin to treat infections caused by some FosA-producing, multidrug-resistant, Gram-negative pathogens.
Type of Medium:
Online Resource
ISSN:
0066-4804
,
1098-6596
DOI:
10.1128/AAC.01424-17
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2017
detail.hit.zdb_id:
1496156-8
SSG:
12
SSG:
15,3
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