In vitro susceptibility of Mycobacterium kansasii to the difluorinated quinolone sparfloxacin using a broth microdilution and macrodilution MIC system.
OBJECTIVE
To study the minimum inhibitory concentrations (MIC) of the difluorinated quinolone sparfloxacin against 32 clinical isolates of Mycobacterium kansasii from 23 patients, all of whom had clinically significant infections due to M. kansasii, and 11 the acquired immune-deficiency syndrome (AIDS). To study the correlation between the microdilution and macrodilution techniques in M7H9 broth.


METHODS
The MICs were determined by two methods: broth microdilution in microplates and broth macrodilution in tubes. The isolates were inoculated into two-fold drug dilutions (ranging from 0.063 to 8 microg/ml) in Middlebrook 7H9 broth and then incubated at 37 degrees C for 21 days.


RESULTS
All 32 strains were susceptible, with identical MIC results in both methods, 96.9% of them showing an MIC of 0.25 microg/ml.


CONCLUSIONS
These MIC studies suggest that sparfloxacin may be useful for drug treatment of slow-growing nontuberculous mycobacteria such as M. kansasii. The microdilution method appears to be a reliable method for routine susceptibility testing of M. kansasii, and is easy to interpret and to carry out.
Royo
P
P
Servicio de Microbiología y Parasitología, Hospitals Vall d'Hebron. Autonomous University, Barcelona, Spain.
Martín-Casabona
N
N
Martínez
E
E
Andonegui
M
M
D000890:Anti-Infective Agents / Q000494:pharmacology*; D000995:Antitubercular Agents / Q000494:pharmacology*; D024841:Fluoroquinolones; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*; D009165:Mycobacterium Infections, Nontuberculous / Q000382:microbiology; D019909:Mycobacterium kansasii / Q000187:drug effects* / Q000254:growth & development
D000890:Anti-Infective Agents; D000995:Antitubercular Agents; D024841:Fluoroquinolones; C061363:sparfloxacin