I have a question regarding antibiotics as positive controls in plant crude extracts antibacterial assay . I am following Dr. Eloff method in the publication at: https://www.researchgate.net/publication/13355248.
I will start by running susceptibility test using the standard agar well diffusion to test the activity of the extracts, then I will run broth Micro-dilution (MIC) for those bacteria that the extracts possess antibacterial activity towards it.
I am using tetracycline, trimethoprim and sulfamethoxazole as positive controls in both tests. However, I do have the powder form of the antibiotics and I am not sure how to prepare the stock solution for these tests. It is a bit confusing.
I apologize if I am taking too much of your time, but kindly please would you recommend to me a procedure to follow regarding this matter?
I am not sure if it is necessary to calculate potency in order to prepare the stock solution of the antibiotics when they will be used as positive controls and the MIC will not be about drug susceptibility but plant crude extracts susceptibility?
The antibiotics I will be using are : Tetracycline T3258 SIGMA http://goo.gl/B4RsMM (12.5 mg/mL) Trimethoprim https://goo.gl/9sreG5 ( 25g per 50mL) Sulfamethoxazole https://goo.gl/mKuMbg (5g per 40mL)
Thank you very much. I'll appreciate your kind help.
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If you look at http://www.ecoseeds.com/mrsa.html comparing the crude plant products with purified chemical antibiotics, I have never done, because it might divert your attention from working with your plant material, or discard potential material because it does not measure up with the purified chemical?
Instead of using the purified antibiotics at all, I would use disks of your plant material like you can see on my website, and measure zone diameters.
Then with your active material, try different parts of the plant to see if there is more activity in parts. For example for one plant that produces fruit, the seeds were the active part. In another plant, the seeds and fruit were inactive, but the stems were active.
Then the next step could be to use grain alcohol and separate your material by molecular weight, and see what molecular weights are more active? Eventually it would be necessary to find out our of the many compounds in a plant extract, which are most active. Of course you could eventually run MICs, but I would still skip the purified antiiotics for that process.
Then are you going just write the information up in a paper and give the information away for free, or file a patent on your discovery, and put your material in to commercial production, so people can cure diseases?
You did not note in your question, WHICH PATHOGENS are you looking to test your potential antibiotics against? I was most working on topicals treatments for MRSA and acne, but also looked for DRSP and VRE. The DRSP would be used for an inhaler for pneumonia and the VRE might be used in surgery.
Dear Shumoos,
You have phrased the question in a very nice manner.
Please check the concentrations you indicated for trimethoprim and sulfamethoxazol (25g per 50 mL and 5g per 40 mL, respectively). They are very high concentrations; it might be that the unit is NOT g but mg.
The following are the solubilities of the three antibiotics in water:
Tetracycline: freely soluble in water
Trimethoprim: 0.4 mg/mL
Sulfamethoxazole: 0.5 mg/mL
There is no need to calculate potency for those antibacterials.
Therefore, you prepare the stock solutions of the three antibacterials in water as suggested in the attached paper
Hoping this will be helpful,
Rafik
What might be more important overall, is that your pathogen culture is a particular strain, like an ATTC culture, so that all of your measurements of your plant antibiotics will be consistent in the future?
Its possible to dock two ligands and one enzyme? Please tell me the right program. Best regards
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