For example, antibiotic X's MIC is reported as >32 µg/ml and MIC plant extraction is reported as >10 µg/ml. what value should we used to calculate the FIC according to the equation? (Combination MIC of antibiotic/MIC of antibiotic alone) + (Combination MIC of extract/MIC of extract alone). And also, what can be done for skipped wells in the microwell plates? What well should we select as combination MIC?
Hello!
Dear Pasindu Ranasinghe, you have to first calculate the MIC of antibiotic and plant extract alone and in combination then only you can get the FIC.
For two different antibacterial agents, for say A and B, acting individually or in combination, you first have to calculate the MIC alone and in combination (A in presence of B and B in presence of A). Then calculate the FIC(A) and FIC(B) by:
FIC(A) = MIC (A in presence of B) / MIC(A alone)
FIC(B) = MIC (B in presence of A) / MIC(B alone)
FIC = FIC(A) + FIC(B).
Thank you.
Hello,
The FIC index is determined by adding the ratio of the MIC of Drug A in combination to its MIC alone and the ratio of the MIC of Drug B in combination to its MIC alone (in your case plant extract and ATB). you would need the MICs of both the antibiotic and the plant extract, both individually and in combination. Without this information, it is not possible to determine the FIC index or assess the interaction between the two substances.
So, to proceed, you would need to determine the MICs of the antibiotics and plant extracts through experimental methods, such as microdilution assays (that I highly recommend) , or other appropriate techniques. Once you have the MICs, you can then calculate the FIC index to evaluate the interaction between the substances.
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