In vitro activity of new fluoroquinolones and linezolid against non-tuberculous mycobacteria.

The objective of the study was to determine the activity of new fluoroquinolones and linezolid against 108 clinical isolates of different species of non-tuberculous mycobacteria isolated in Spain. Gatifloxacin and moxifloxacin were found to be more effective than levofloxacin. Mycobacterium kansasii was more susceptible to the fluoroquinolones tested than M. avium complex and M. fortuitum was more susceptible than M. chelonae. Linezolid was more active against M. kansasii than against M. avium complex. A better understanding of the relationship between the in vitro activity of these compounds and their usefulness in the treatment of these infections is needed. The new fluoroquinolones exhibit good activity against M. kansasii and M. fortuitum and linezolid is active against M. kansasii.