Friday, March 4, 2011

Bacteria + High School Students = Gross.

Just yesterday in Bio class we did a disinfectant and antiseptic lab to see how it effected the bacteria on  normal everyday things that we touch and use. We all have heard of what disinfectants and antiseptics but to we really know what they are and what they are used for? This post is primarily based on what I did during the lab and what I found out about the bacteria lurking in our school.

First, let me explain what disinfectants and antiseptics are for those of you who don't know.
Both of these substances are agents that kill, or at least control the growth of bacteria.  Antiseptics are used on living tissue while disinfectants are used on non-living things such as floors, counter tops, dishes, stall doors, etc. Of course the disinfectant bleach worked the best because it has harsher chemicals, which is also the reason why we don't use it on living things because it would probably eat our skin or something.

On to the lab...
We started this lab off with some agar in a petri dish. We had to first swab our index finger with a clean cotton swab and we put that onto it's section on the agar. We did the same thing to the second and third section except we used alcohol on one and soap on the other. After we had swabbed some bacteria off or our skin we got to choose what we wanted our surface to be. I chose...drum roll please...the nasty stall door in the girls bathroom. I figured that after we girls get done with our business we have to open the door all before we wash our hands or anything. So I was curious as to see how much bacteria there actually was. I swabbed that with just a clean cotton swab, one drenched in alcohol, and one drenched in bleach. 

After we had done  with that we put our petri dish into an incubator for two days to let the bacteria grow. And what a delight it was to find out how dirty the stall door actually was.
It ended up being that my skin really wasn't that 'dirty', which could be because I am a cleanly person or our hands really just don't get very dirty. But I did have more bacteria on my hand when I didn't use the alcohol and soap. I had NOTHING on the finger I used alcohol in. I guess our doctors are pretty smart using that to clean our skin before shots. But the finger that I washed with antibacterial soap still had some bacterial growth, which kind of bothered me. But it's not like I will from now on wash my hands with alcohol. The soap did a pretty good job, I guess.

As for the stall door, there was A LOT of growth. It practically covered all of the section it was in. Not good. But what do we expect? People don't have a chance to wash their hands RIGHT after we go to the bathroom. Thank goodness we have sinks. The part of the door that I treated with alcohol had less bacteria, but still quite a bit and the part of the door that I swabbed with bleach only had one growth. Bleach is kind of awesome.

And I just thought I should insert this into my post. I later put the bacteria of the normal stall under a microscope and found that it was bacillus. Very interesting...


  1. Wow - This post is really interesting! This kind of stuff always fascinates me.

    KF x

  2. wow!!! gross!!!

    xoxo from rome

    (LAST day of my GIVE-AWAY)

  3. Amazing. I'm more than addicted to alcohol gel. x hivennn

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  5. Interesting!!

    Monique xx