A microplate indicator-based method for determining the susceptibility of multidrug-resistant Mycobacterium tuberculosis to antimicrobial agents.

Setting: Reference Laboratory, Buenos Aires Province Tuberculosis Control Program, Dr Cetrangolo Hospital, Argentina.

Objective: To obtain a rapid, inexpensive method of determining minimal inhibitory concentrations (MIC) of several drugs acting on multidrug-resistant Mycobacterium tuberculosis (MDR-TB), a colorimetric, microplate-based assay (M-MTT) was developed.

Design: One hundred and one clinical isolates were studied.