I am doing research by using Phaleria macrocarpa's fruit extract that used 2 different types of solvents. I did the disc diffusion test , and it resulting few of the samples can act as antimicrobial agnet. Then i proceed with MIC . I used UV-vis to determine the turbidity of samples , before and after incubation period. The sample that shown decreased reading after the incubation , i assume it as antimicrobial agent. Then , i streak the sample for MBC test , but end up there's still growth on the agar. What should i do ?
It seems that this extract have a bacteriostatic activity without being bactericidal agaist tested bacterial strains.
It can be large different between amount of MIC and MBC.
So you have to use more con of your agent to determine that your agent are bactericidal or not?
Dear Alysha
You must understand that the MIC is the lowest concentration of antimicrobial agents which inhibits bacterial growth after overnight incubation while MBC the same definition but kills instead of inhibits. In your above mention, this concentration is not cidal but static because if it is cidal, no any growth of bacteria appears. Also, normally the MICs will show growth after overnight inhibition effect, after that re-growth of bacteria will occurred.
To detect MBCs, you must transfer a loopful of inoculum from the the tubes which shows no turbidity. for example, if MIC is 4, MBCs may be 4 or 8 or 16 and not means MBC is the same as MIC.
Hope the answer to be benefit. Best regard
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