In vitro sensitivity of Mycobacterium xenopi to five antibiotics.

We tested 20 strains of Mycobacterium xenopi (M. xenopi) in order to evaluate their in vitro sensitivity to amikacine, clarithromycine, ethambutol, ofloxacine and rifampicin, by establishing minimal inhibitory concentration (MIC) on agar medium. MICs of amikacine, clarithromycine and ofloxacine are low, so that these antibiotics can be used in the treatment of M. xenopi infections. MICs of ethambutol are higher than seric concentrations. Though, its therapeutic use is due to its in vivo ability to enhance penetration of other antibiotics in mycobacteria. Strain sensitivity to rifampicin seems heterogeneous but the small number of tested strains does not entitle the exclusion of rifampicin from the treatment of M. xenopi infections.