Following are two method you can try and check if you are doing the same thing.

If you have doubt with MH media, you are try LB or any other media to compare. Although, what might change the MIC numbers, but you can see the trend and effect of which media is better for your peptide analysis.

http://cmdr.ubc.ca/bobh/method/modified-mic-method-for-cationic-antimicrobial-peptides/

http://cmdr.ubc.ca/bobh/method/mic-determination-by-microtitre-broth-dilution-method/

You can try with liquid broth lb or with TSB tryptivase soja broth

You can use tetrazolium chloride to visualize growth regardless of the turidity. It is a colorless compound and turns red in the presence of living bactria

Few methods could be considered.

1. Tetrazolium salts have been used in broth micro-dilution to enhance the detection of bacterial growth in different studies. TTC is used to differentiate between metabolically active and inactive tissues. The white compound is enzymatically reduced to red TPF (1,3,5-triphenylformazan) in living tissues due to the activity of various dehydrogenases (enzymes important in oxidation of organic compounds and thus cellular metabolism).

2. Use plate reader measure its OD600 at 0h, and 24h. Final data should minus the 0h data which is background.

Hope it helps.