I am doing a resazurin assay to determine the MIC of plant extracts against Mycobacterium tuberculosis. The problem is the MIC is coming at a very high value. I read in one paper that even if there are 80 cells the color changes from blue to pink. I am diluting the inoculum also (1:20 dilution). How to solve this problem. Kindly give suggestions. Should I dilute the inoculum more?