Thread: Microbiology Science Project-Advice would be appreciated

Hello All,
I would like to do a microbiology project where I test the effectiveness of several herbal extracts using the Kirby-Bauer method on one of the following bacteria strains:
Acinetobacter baumannii,
Escherichia coli
Klebsiella pneumoniae bearing extended-spectrum β-lactamases (ESBL)
vancomycin-resistant enterococci (VRE)
methicillin-resistant Staphylococcus aureus (MRSA)
vancomycin-resistant MRSA
extensively drug-resistant (XDR) Mycobacterium tuberculosis

I have no previous experience in microbiology, and do not have access to any lab other than the one in my school. I have several questions. How would I obtain any of the above bacteria? I have read that there is a much weaker K-12 strain of e.coli, but I would like to do a project that had real-world significance. Is it alright to do the Kirby-Bauer method in a school lab? I have read several descriptions of the method and they are all different. How exactly would you describe the method? Do I need a teacher who is well-versed in microbiology to supervise me?

Thanks, and sorry for the long post

I admire the purpose of your project, yet working with MRSA species and M. tuberculosis requires specialized laboratories.
Studying MRSA species must be done in BSL-2 laboratories and tests performed on XDR M. tuberculosis must be done in a BSL-3 laboratory.
You first need to check if the laboratory in your school is equipped with the materials designed to handle those bacteria and then you need to check if your school is in order with the necessary safety requirements. If you are searching for bacteria, then you might check out ATCC or ProMega.

Second, the Kirby-Bauer method is an easy method. Thus I do not see any problems with that.
Feel free to check the protocols as put forward by the ASM.
(cf. Kirby-Bauer Disk Diffusion Susceptibility Test Protocol).

Last, but not least, it is advisable (or even required) to have a supervisor who assists you in your experiments.
Furthermore, you should get an introduction into the methods of microbiology, considering the fact that you have no previous experience in the field.


PS: Are you sure about working with those (highly) pathogenic strains?

I don't know what your situation is like but when I wanted to do a microbiology project I just asked my micro professor and she provided me with everything I needed (including the lab to do it in).

Hmm... some truly fascinating organisms you have listed there. I have a real hard time believing that you would be allowed anywhere near half of them.

thanks for the responses, I realize I was getting a bit ahead of myself. I'll use the K-12 strain, as I'm still in high school, and I'll try to find a teacher. Just one more question: The link Cogito Ergo Sum mentioned (very helpful, btw) said "When a 6-mm filter paper disk impregnated with a known concentration of an antimicrobial compound is placed on a Mueller-Hinton (MH) agar plate"--- is it possible to use LB agar instead of muller-hinton agar? I also read that for inoculating the bacteria, one must use LB agar.
The reason is that MH agar is 30% beef heart infusion, and I'm a vegetarian. Again, thanks for all the quick replies I've received on this forum.

Originally Posted by hello1019

"When a 6-mm filter paper disk impregnated with a known concentration of an antimicrobial compound is placed on a Mueller-Hinton (MH) agar plate"--- is it possible to use LB agar instead of muller-hinton agar? I also read that for inoculating the bacteria, one must use LB agar.

Although LB agar is widely used (especially for E. coli strains), it is not advisable to use it for your project.
Those pathogenic strains might need additional compounds ('enriched media'). You need to check what the optimal medium is, in order to grow a culture.

If you are working with pathogenic bacteria it is important that the growth medium be what they eat, not what you eat. These bacteria are NOT vegetarians. They eat US. If you use a vegtable based growth medium it alters the meaning of the experiment making it far less applicable to human medicine. We are not generally bothered by organisms that want to eat only vegtables.

Great decision going with E. coli. This bacteria is not particularly pathogenic (unless you come across the wrong strain, that is!) and it has been studied extensively, so it is extremely important microbe. You can purchase E. coli from almost any bio supply store because it is so common, but you might try the ATCC (this source will DEFINITELY have it). E. coli will grow on just about everything (as long as you have the proper amino acids and a carbon source, as your generic Luria Bertani "lysogeny broth" (LB) does provide), so I think LB will be fine for the purposes of your experiment, and it is very easy to find.

Another option for doing an antibiotic-resistance test is to streak a plate with a cotton swab wiped over a hand rail or door knob in your school and then to count the number of colonies that are able to grow within the zone of inhibition presented by your antibiotic. This would be a very relevant experiment, although you will likely not be able to identify the bacteria and you will also probably get some fungi that could confound your results. But it would still be a very cool, simple microbio project.