RESUMEN
MICs of plazomicin were determined by agar dilution and broth microdilution in 187 ESBL-producing Escherichia coli (nâ¯=â¯73), carbapenemase-producing Klebsiella pneumoniae (nâ¯=â¯55) methicillin-resistant Staphylococcus aureus (nâ¯=â¯59) clinical isolates. Inoculum effect was determined by broth microdilution assay using two different inocula; 1-5 × 105 (standard inoculum) and 1-5â¯×â¯108â¯CFU/mL. For all isolates tested >98% categorical agreement and ≥95% of essential agreement (±1elog2) was found. At high inocula, MICs of plazomicin increased ≥ eight-fold for 25% of E. coli, 24% of K. pneumoniae and 7% of S. aureus isolates tested. The results indicate that agar dilution and broth microdilution methods were equally suitable for determining plazomicin MICs. Inoculum effect was observed for plazomicin in Escherichia coli and Klebsiella pneumoniae isolates. Further studies that establish the genetic background of the isolates are required to better understand the reasons behind the inoculum effect.
Asunto(s)
Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Farmacorresistencia Bacteriana/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/métodos , Sisomicina/análogos & derivados , Bacterias/enzimología , Carga Bacteriana , Proteínas Bacterianas/biosíntesis , Escherichia coli/efectos de los fármacos , Escherichia coli/enzimología , Humanos , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/enzimología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Sisomicina/farmacología , beta-Lactamasas/biosíntesisRESUMEN
The activity of plazomicin and clinically relevant aminoglycosides was tested against 346 extended-spectrum-ß-lactamase/AmpC-producing Escherichia coli urinary isolates, and the results were correlated with the presence of aminoglycoside-modifying enzymes (AMEs). Data showed that plazomicin was very active against all ESBL/AmpC-producing E. coli urinary isolates. Its activity was not related to the AME genes studied.