Resistant bacteria...?

For science fair, I'm considering doing a project with resistant bacteria. Basically, I would grow bacteria, then expose it to hand sanitizer, rubbing alchohol, or anti-bacterial soap. (Woo-hoo, IV) Whatever is left, I would reproduce and expose it again and again, to see how long it takes the bacteria to become resistant. (Woo-hoo, DV) There's just one problem. What would I do with the resistant bacteria when the experiment is done? How do I kill it off? Any biologists in here have any ideas?

Resistant bacteria...?
First off, this is an excellent idea for a science fair project. To answer your questions, there are a variety of ways to kill the remaining bacteria. The most obvious one would be to autoclave it. This will ensure that you kill all the bacteria. Others things you can use is bleach (at least 10%) or 70% isopropanol. This leads me to a few things that you may want to consider.





First, you need to consider what bacteria and antimicrobial angent you are going to use. Despite what other posters have said, you can use E. coli, as long as you use a common lab strain that is not pathogenic, such as DH5-alpha or BL21. Talk to your instructor/microbiologist for help with this. DH5-alpha is a well characterized E. coli strain that is often used in the laboratory. It is generally non-pathogenic to humans but you will want to still exercise caution when working with this bacterium (or any for that matter). There are other bacteria that you can use too. One word of caution, some of these laboratory strains are susceptible to many antimicrobial agents and are pretty weak overall. You may have a hard time developing resistance in some of these strains.





Second, and if I may offer a little advice, you might want to reconsider what type of agent you are exposing it to. You might not get very good results with these alcohol based agents. What I mean is bacteria generally do not develop resistance to alcohol. If you were going to expose bacteria to rubbing alcohol, it would kill all of the bacteria leaving you with nothing and ending your experiment.





Anti-bacterial soap would be interesting to try. There is some contreversy over the active ingredient in these soaps (Triclosan). The main anti-microbial activity from the use of hand soap is the mechanical removal of bacteria from your hands by scrubbing. Triclosan is found in many products, not just hand soap. One of my former professors who is now head of the Nation Antimicrobial Resistance Monitoring System (NARMS) for the FDA was/is a big opponent of the overuse of triclosan.





One other thing I would consider is using a specific antibiotic for your antimicrobial agent. Start out trying to grow the bacteria on low concentrations of antibiotic, then slowly increase the concentration with each passage. I have done this with Naladixic Acid in E. coli for use in the laboratory. Another word of caution, this may not work with all antibiotics and some will work better than others.





I hope this helps you out. Talk with you instructor/microbiologist for help designing your experiment. If you need more help, feel free to email me.
Reply:Wow, that would be tough. I guess the best way to kill anything is to take it to a Fergie concert.
Reply:First off, how old are you? If this science fair is for anything below high school/college, then no. Do NOT do your own studies in resistant bacteria. The reason is, what if you contaminate yourself or other people because those strains are resistant?





What bacteria are you growing? You must know your strain, because on the off chance that whatever you swab off turns out to be staph or E-Coli, you could cause a lot of problems. Therefore, you need more involved equpiment than normal people might have access to.





But in order to kill off strains resistant to hand sanitizer and the like? Bleach. Full concentration, immersed for a long time.
Reply:Take a base strain of a bacterium. Staphyllococcus epidermidis come to mind.





Prepare a base culture on a slant. Store it as a reference culture.





Use liquid culture media. Add isopropyl alcohol to fixed concentrations, say 2%, 4%, 8% and 16%.





Suspend some bacteria from the slant in base medium to and grow to a fixed optical density to innoculate your culture media.





Grow the bacteria in the various culture media, plus one without alcohol for 4 hours at 37C.





Use serial dilutions and plate to determine the quantity of bacteria at the end of incubation.





The next day, repeat the experiment.





Take two colonies that grew on alcohol-free medium and two that grew at the highest concentration media that allowed growth.





Repeat the procedure with the four colonies, for 9 passes.





When you do a 10th pass, take the original slant and streak it for colonies. Take two colonies from the slant, two from the no alcohol group and two from the high alcohol group. And repeat the experiment.
Reply:First use something harmless for your subject.


(Your teacher can advise, maybe provide).


You can kill the resistant results by boiling.
Reply:Firstly, love to hear from young budding scientists! u go girl!!


If you want to work with resistance and stress adaptation, you would certainly need to autoclave the bacteria afterwards, to kill it, and then you could dispose of it. Im guessing you teachers could make this available for you.


BEST LUCK WITH IT. :)