Molecular mechanisms of fosfomycin resistance in clinical isolates of Escherichia coli.
To clarify the molecular mechanisms of fosfomycin resistance in clinical isolates of Escherichia coli, the murA, glpT, uhpT, uhpA, ptsI and cyaA genes were sequenced from six fosfomycin-resistant isolates. Two strains were found to harbour a mutation in the murA gene that leads to an amino acid substitution (Asp369Asn or Leu370Ile) in the target protein. The remaining four strains carried specific mutations in the glpT gene; one strain possessed a mutation and the other three strains possessed truncated versions of the GlpT transporter owing either to the presence of insertion sequences or a deletion in the coding region of the gene. Two of the strains with truncated GlpT had also lost the entire uhpT gene, which encodes another fosfomycin transporter. Uptake of specific substrates for the transporters was either totally blocked or reduced in strains possessing truncated forms of GlpT or those lacking the uhpT gene. Escherichia coli strains expressing an amino-acid-substituted MurA were at least eight-fold more resistant to fosfomycin than the strain overproducing wild-type MurA. In conclusion, novel amino acid substitutions in MurA or the loss of function of transporters were identified as mechanisms of fosfomycin resistance in clinical isolates of E. coli.
Takahata
Sho
S
Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd., 760 Morooka-cho, Kohoku-ku, Yokohama, Japan. sho_takahata@meiji.co.jp
Ida
Takashi
T
Hiraishi
Toru
T
Sakakibara
Shiro
S
Maebashi
Kazunori
K
Terada
Shinichi
S
Muratani
Tetsuro
T
Matsumoto
Tetsuro
T
Nakahama
Chikara
C
Tomono
Kazunori
K
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics; D005578:Fosfomycin / Q000494:pharmacology*; D006801:Humans; D054643:INDEL Mutation; D008826:Microbial Sensitivity Tests; D020125:Mutation, Missense; D017422:Sequence Analysis, DNA
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D005578:Fosfomycin