Emergence of imipenem resistance in clinical Escherichia coli during therapy

Oteo, J., Delgado-Iribarren, A., Vega, D., Bautista, V., Rodríguez, M. C., Velasco, M., Saavedra, J. M., Pérez-Vázquez, M., García-Cobos, S., Martínez-Martínez, L. & Campos, J., Dec-2008, In : International journal of antimicrobial agents. 32, 6, p. 534-537 4 p.

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  • Emergence of imipenem resistance in clinical Escherichia coli during therapy

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  • Jesús Oteo
  • Alberto Delgado-Iribarren
  • Dolores Vega
  • Verónica Bautista
  • María Cruz Rodríguez
  • María Velasco
  • José María Saavedra
  • María Pérez-Vázquez
  • Silvia García-Cobos
  • Luis Martínez-Martínez
  • José Campos

The molecular epidemiology and the mechanisms of resistance of Escherichia coli isolated from two patients infected by imipenem-resistant strains are reported in this study. From one patient, three closely related consecutive isolates of E. coli were recovered; the first was carbapenem-susceptible but acquired imipenem resistance after treatment with ertapenem, and the third isolate was again imipenem-susceptible. An additional imipenem-resistant isolate was recovered from another patient who received imipenem. The genetic relatedness of the E. coli isolates was determined by pulsed-field gel electrophoresis (PFGE) after digestion with XbaI. Standard polymerase chain reaction (PCR) conditions were used to amplify several beta-lactamase genes coding for carbapenemases, extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC; the E. coli ampC gene promoter was also amplified and sequenced. Primers OmpF-F/OmpF-R and OmpC-F/OmpC-R were used to amplify the ompF and ompC genes. The outer membrane protein (OMP) profiles were studied by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Imipenem-resistant E. coli isolates did not produce carbapenemases but lacked the two major OMPs OmpF and OmpC and had ampC promoter mutations; in addition, one of the imipenem-resistant isolates produced the CMY-2 cephalosporinase, whilst the other produced the new CTX-M-67 ESBL. Carbapenem resistance in this study was associated with lack of expression of OmpF and OmpC porins. Additional mechanisms of beta-lactam resistance, such as plasmid-mediated AmpC and ESBL production, were also found. Development of carbapenem resistance in a CTX-M-67-producing E. coli is first described in this study.

Original languageEnglish
Pages (from-to)534-537
Number of pages4
JournalInternational journal of antimicrobial agents
Issue number6
Publication statusPublished - Dec-2008


  • Anti-Bacterial Agents/pharmacology, Bacterial Outer Membrane Proteins/genetics, Conjugation, Genetic, Drug Resistance, Bacterial, Electrophoresis, Gel, Pulsed-Field, Escherichia coli/drug effects, Escherichia coli Infections/drug therapy, Female, Genes, Bacterial/genetics, HIV Infections/microbiology, Humans, Imipenem/pharmacology, Microbial Sensitivity Tests, Middle Aged, Mutation, Surgical Wound Infection/drug therapy, Virulence Factors/genetics, beta-Lactamases/genetics

ID: 83373747