In Vitro Susceptibility of Nocardia asteroides and Nocardia brasiliensis to 1-N-derivatives of Aminoglycoside Antibiotics

Four l-N-substitute aminoglycosides were tested for their in vitro activity against the Nocardia asteroides group and Nocardia brasiliensis by agar dilution method. Among these aminoglycosides, the recently developed arbekacin, l-N-((S)-4- amino-2-hydroxybutyryl)-3',4'dideoxykanamycin B, had the best activity, showing the respective MIC90 values of 1.25 and 1.55 ug/ml against the N. asteroides group and N. brasiliensis. The activity of arbekacin is higher than that of amikacin, followed by isepamicin and netilmicin. Recently established Nocardia species, i.e., N. asteroides sensu stricto, N. nova and N. farcinica from the N. asteroides group were sensitive to these aminoglycosides, but showed different sensitivity patterns.