Novel Fosfomycin Resistance of
            <b>
              <i>Pseudomonas aeruginosa</i>
              Clinical Isolates Recovered in Japan in 1996
            </b>

Shimizu, Masaki; Shigenobu, Fritz; Miyakozawa, Izumi; Nakamura, Akio; Nakazawa, Katsuhito; Suzuki, Masato; Mizukoshi, Satoko; Ohara, Koji; Sawai, Tetsuo; Chemistry, Division of Microbial

doi:10.1128/aac.44.7.2007-2008.2000

Cited by 20 publications

(9 citation statements)

References 7 publications

(7 reference statements)

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“…Thus, activation of expression of these genes during anaerobic growth may be reasonable from a physiological standpoint for EHEC to reduce the metabolic cost. This concept is also supported by epidemiologic data showing that susceptibility rates have remained relatively stable despite the prevalent use of fosfomycin, though mutants that are resistant to fosfomycin can frequently be isolated from in vitro laboratory cultures (35)(36)(37)(38)(39). A loss of biological fitness, together with conferred resistance, offers the benefit that the development of resistance to the drug could occur with a low possible incidence even if its use increases in the future.…”

Section: Discussionmentioning

confidence: 61%

Elevated Expression of GlpT and UhpT via FNR Activation Contributes to Increased Fosfomycin Susceptibility in Escherichia coli under Anaerobic Conditions

Kurabayashi

Tanimoto

Fueki

et al. 2015

Antimicrob Agents Chemother

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Because a shortage of new antimicrobial agents is a critical issue at present, and with the spread of multidrug-resistant (MDR) pathogens, the use of fosfomycin to treat infections is being revisited as a "last-resort option." This drug offers a particular benefit in that it is more effective against bacteria growing under oxygen-limited conditions, unlike other commonly used antimicrobials, such as fluoroquinolones and aminoglycosides. In this study, we showed that Escherichia coli strains, including enterohemorrhagic E. coli (EHEC), were more susceptible to fosfomycin when grown anaerobically than when grown aerobically, and we investigated how the activity of this drug was enhanced during anaerobic growth of E. coli. Our quantitative PCR analysis and a transport assay showed that E. coli cells grown under anaerobic conditions had higher levels of expression of glpT and uhpT, encoding proteins that transport fosfomycin into cells with their native substrates, i.e., glycerol-3-phosphate and glucose-6-phosphate, and led to increased intracellular accumulation of the drug. Elevation of expression of these genes during anaerobic growth requires FNR, a global transcriptional regulator that is activated under anaerobic conditions. Purified FNR bound to DNA fragments from regions upstream of glpT and uhpT, suggesting that it is an activator of expression of glpT and uhpT during anaerobic growth. We concluded that the increased antibacterial activity of fosfomycin toward E. coli under anaerobic conditions can be attributed to elevated expression of GlpT and UhpT following activation of FNR, leading to increased uptake of the drug.

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Section: Discussionmentioning

confidence: 61%

Elevated Expression of GlpT and UhpT via FNR Activation Contributes to Increased Fosfomycin Susceptibility in Escherichia coli under Anaerobic Conditions

Kurabayashi

Tanimoto

Fueki

et al. 2015

Antimicrob Agents Chemother

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“…In support of this hypothesis, mutants that are resistant to fosfomycin can be frequently isolated in vitro (24,25). However, epidemiologic data indicate that susceptibility rates have remained relatively stable since the introduction of this agent in clinical practice (26)(27)(28).…”

mentioning

confidence: 94%

Role of the CpxAR Two-Component Signal Transduction System in Control of Fosfomycin Resistance and Carbon Substrate Uptake

Kurabayashi¹,

Hirakawa²,

Tanimoto³

et al. 2013

Journal of Bacteriology

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Although fosfomycin is an old antibiotic, it has resurfaced with particular interest. The antibiotic is still effective against many pathogens that are resistant to other commonly used antibiotics. We have found that fosfomycin resistance of enterohemorrhagic Escherichia coli (EHEC) O157:H7 is controlled by the bacterial two-component signal transduction system CpxAR. A cpxA mutant lacking its phosphatase activity results in constitutive activation of its cognate response regulator, CpxR, and fosfomycin resistance. We have shown that fosfomycin resistance requires CpxR because deletion of the cpxR gene in the cpxA mutant restores fosfomycin sensitivity. We have also shown that CpxR directly represses the expression of two genes, glpT and uhpT, which encode transporters that cotransport fosfomycin with their native substrates glycerol-3-phosphate and glucose-6-phosphate, and repression of these genes leads to a decrease in fosfomycin transport into the cpxA mutant. However, the cpxA mutant had an impaired growth phenotype when cultured with glycerol-3-phosphate or glucose-6-phosphate as a sole carbon substrate and was outcompeted by the parent strain, even in nutrient-rich medium. This suggests a trade-off between fosfomycin resistance and the biological fitness associated with carbon substrate uptake. We propose a role for the CpxAR system in the reversible control of fosfomycin resistance. This may be a beneficial strategy for bacteria to relieve the fitness burden that results from fosfomycin resistance in the absence of fosfomycin.

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“…Furthermore, the residues highlighted in this channel (with the exception of Trp 46 ) contain a hydroxyl or thiol side chain that could be involved in activating and/or stabilizing GSH/GS Ϫ . The low toxicity and broad-spectrum bactericidal activity of fosfomycin have resulted in its increased clinical use, which in turn has resulted in fosfomycin-resistant strains (7,8). Currently, there are no inhibitors to combat FosA-mediated fosfomycin resistance.…”

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confidence: 99%

Functional Analysis of Active Site Residues of the Fosfomycin Resistance Enzyme FosA from Pseudomonas aeruginosa

Beharry

Palzkill

2005

Journal of Biological Chemistry

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The metalloglutathione transferase FosA catalyzes the conjugation of glutathione to carbon-1 of the antibiotic fosfomycin, rendering it ineffective as an antibacterial drug. Codon randomization and selection for the ability of resulting clones to confer fosfomycin resistance to Escherichia coli were used to identify residues critical for FosA function. Of the 24 codons chosen for randomization, 16 were found to be essential because only the wild type amino acid was selected. These included ligands to the Mn 2؉ and the K ؉ , residues that furnish hydrogen bonds to fosfomycin, and residues located in a putative glutathione/fosfomycin-binding site. The remaining eight positions randomized were tolerant to substitutions. Site-directed mutagenesis of some of the essential and tolerant amino acids to alanine was performed, and the activity of the purified proteins was determined. Mutation of the residues that are within hydrogen bonding distance to the oxirane or phosphonate oxygens of fosfomycin resulted in variants with very low or no activity. Mutation of Ser 94 , which bridges one of the phosphonate oxygens with a potassium ion, resulted in insoluble protein. The Y39A mutation in the putative glutathione-binding site resulted in a 4-fold increase in the apparent K m for glutathione. Only two of the amino acids in the substrate-binding site are conserved in the related fosfomycin resistance proteins FosB and FosX, whereas no amino acids in the putative glutathione-binding site are conserved.

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Novel Fosfomycin Resistance of Pseudomonas aeruginosa Clinical Isolates Recovered in Japan in 1996

Cited by 20 publications

References 7 publications

Elevated Expression of GlpT and UhpT via FNR Activation Contributes to Increased Fosfomycin Susceptibility in Escherichia coli under Anaerobic Conditions

Elevated Expression of GlpT and UhpT via FNR Activation Contributes to Increased Fosfomycin Susceptibility in Escherichia coli under Anaerobic Conditions

Role of the CpxAR Two-Component Signal Transduction System in Control of Fosfomycin Resistance and Carbon Substrate Uptake

Functional Analysis of Active Site Residues of the Fosfomycin Resistance Enzyme FosA from Pseudomonas aeruginosa

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