Inhibition of fosfomycin resistance protein FosA by phosphonoformate (foscarnet) in multidrug-resistant gram-negative pathogens

Ryota Ito, Adam D. Tomich, Christi L. McElheny, Roberta T. Mettus, Nicolas Sluis-Cremer, Yohei Doi

Research output: Contribution to journalArticle

5 Citations (Scopus)

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 (FosAKP), Enterobacter cloacae (FosAEC), and Pseudomonas aeruginosa (FosAPA) 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 (Km) for fosfomycin in a dose-dependent manner, without affecting the maximum rate (Vmax) of the reaction, for all four FosA enzymes tested, indicating a competitive mechanism of inhibition. Inhibitory constant (Ki) values were 22.6, 35.8, 24.4, and 56.3 M for FosAKP, FosAEC, FosAPA, and FosA3, respectively. Addition of clinically achievable concentrations of PPF (667 M) 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 re-purposed as an adjuvant for fosfomycin to treat infections caused by some FosA-producing, multidrug-resistant, Gram-negative pathogens.

Original languageEnglish
Article numbere01424
JournalAntimicrobial agents and chemotherapy
Volume61
Issue number12
DOIs
Publication statusPublished - 01-12-2017

Fingerprint

Foscarnet
Fosfomycin
Enterobacter cloacae
Klebsiella pneumoniae
Proteins
Pseudomonas aeruginosa
Antiviral Agents
Glutathione
Escherichia coli
Anti-Bacterial Agents

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

Cite this

Ito, Ryota ; Tomich, Adam D. ; McElheny, Christi L. ; Mettus, Roberta T. ; Sluis-Cremer, Nicolas ; Doi, Yohei. / Inhibition of fosfomycin resistance protein FosA by phosphonoformate (foscarnet) in multidrug-resistant gram-negative pathogens. In: Antimicrobial agents and chemotherapy. 2017 ; Vol. 61, No. 12.
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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 (FosAKP), Enterobacter cloacae (FosAEC), and Pseudomonas aeruginosa (FosAPA) 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 (Km) for fosfomycin in a dose-dependent manner, without affecting the maximum rate (Vmax) of the reaction, for all four FosA enzymes tested, indicating a competitive mechanism of inhibition. Inhibitory constant (Ki) values were 22.6, 35.8, 24.4, and 56.3 M for FosAKP, FosAEC, FosAPA, and FosA3, respectively. Addition of clinically achievable concentrations of PPF (667 M) 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 re-purposed as an adjuvant for fosfomycin to treat infections caused by some FosA-producing, multidrug-resistant, Gram-negative pathogens.",
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Inhibition of fosfomycin resistance protein FosA by phosphonoformate (foscarnet) in multidrug-resistant gram-negative pathogens. / Ito, Ryota; Tomich, Adam D.; McElheny, Christi L.; Mettus, Roberta T.; Sluis-Cremer, Nicolas; Doi, Yohei.

In: Antimicrobial agents and chemotherapy, Vol. 61, No. 12, e01424, 01.12.2017.

Research output: Contribution to journalArticle

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