RESUMEN
INTRODUCTION: Ceftolozane/tazobactam is a novel antibiotic approved for the treatment of complicated intra-abdominal and complicated urinary tract infections. CASE DESCRIPTION: We describe the use of off-label ceftolozane/tazobactam in the management of a multidrug-resistant Pseudomonas aeruginosa bacteremia that was already being treated with colistin and amikacin, the only active antibiotics according to the antibiogram.
Asunto(s)
Antibacterianos/uso terapéutico , Bacteriemia , Cefalosporinas/uso terapéutico , Ácido Penicilánico/análogos & derivados , Infecciones por Pseudomonas , Pseudomonas aeruginosa/efectos de los fármacos , Antibacterianos/farmacología , Bacteriemia/tratamiento farmacológico , Bacteriemia/epidemiología , Bacteriemia/microbiología , Cefalosporinas/farmacología , Farmacorresistencia Bacteriana Múltiple , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Uso Fuera de lo Indicado , Ácido Penicilánico/farmacología , Ácido Penicilánico/uso terapéutico , Infecciones por Pseudomonas/tratamiento farmacológico , Infecciones por Pseudomonas/epidemiología , Infecciones por Pseudomonas/microbiología , TazobactamRESUMEN
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.