HELP with Minimum Inhibitory Concentration (MIC) calculations

Candace Krepel ckrepel at
Wed Mar 27 13:41:52 EST 1996

Nathaniel Sopelario (nate at wrote:
: Mark Fuller wrote:
: > 
: > I have just conducted some experiments to determine the minimum
: > inhibitory concentration (MIC) of a chemical and a bunch of different
: > bacteria.  I have data covering the initial compound concentrations, the
: > optical density (OD) over time of the cultures and the final compound
: > and metabolite concentrations.
: > 
: > 1) What should be graphed versus what?  Initial concentration vs. OD
: > gives a good trend, but is there any model/equation I can use to figure
: > out the MIC?  I can eyeball it, but I'd much rather do it
: > mathematically.
:    In Excel 5, there's a tool to have a mathematical representation of 
: the graph created by the variables chosen. You can play around with it 
: to determine an equation. 

Alternatively, you could use the well-established procedures of NCCLS to
determine MIC.

Candy Krepel
Surgical Microbiology Research Lab, Medical College of Wisconsin
ckrepel at

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