December 5th

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Dear Blog and Blog Readers,

Today was our final Medical Microbiology lab. We concluded with observing our results of the previous lab. The green and red demonstrate the normal diffusion of liquid through the agar while the antibodies and antigens respond differently. The antibodies block the movement of the antigens. This looks like an arc wave in the agar at the point where the antigens are stopped.

December 3rd

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Dear Blog, and Blog Readers,

Today we conducted an experiment in which we tested the abilities of antibodies to respond to antigens . . . 

We used this container with twelve wells to begin our experiment

We were instructed to place fifty microliters of "A6" into every well. After we did this, we waited five minutes. Then, once the antigens firmly attached to the well walls, we tapped the wells onto paper towels to remove the excess liquid. After this, we filled each well with a purifying liquid and we tapped the wells out in the same way as before.

We then put fifty microliters of "20" in the wells labeled "20" and fifty microliters of "39" in the wells labeled "39." 

Once again, we tapped the liquid out of the wells

We used the micro pipet to insert the precise amount of liquid into the wells

The last six wells turned blue in response to adding the antibodies to the wells

After we completed our first experiment, we began our next experiment involving the yellow and red dots seen on the petri dish. These dots are used to determine diffusion patterns of the colors in comparison to the diffusion of the antibodies and antigens as will be seen during the next class. . .

Thursday, November 14th

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Dear Blog and Blog Readers, 

Today in microbiology we checked the agar plate we infected with bacteria from the sink handle to see which disinfectant inhibited the bacteria growth. 

However, as seen on this plate, the bacteria did not grow at all. Therefore, we decided to test a new area. This time, I took a swab from the bathroom sink handle assuming that those handles are cleaned less than those in the lab. 

Here is the new plate:

We placed this in the 25 degree Celsius incubator (room temperature and will check it next class.)

Next we took plates out of the an-ox tank they were in to see if lack of oxygen inhibited bacteria growth.

The bacteria still grew in this environment. Therefore it can be concluded that our bacteria is facultative aerobe because it did not thrive but it survived. 

Next, we began to fill out a sheet summarizing all the tests we have done to determine the bacteria we have, but did not find the answer just yet...read the next few posts to find out!

Tuesday, November 12th

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Dear Blog and Blog Readers, 

Today we check the blood agar plates that were infected with bacteria from our noses. 



It appears only Samantha had an indication of S. aureus. However, there is only partial lysis, so it is a form of Staph but not the bacteria in it's most dangerous form.



We also swabbed a sink handle and infected a nutrient agar plate with the bacteria. We then split the plate into 4 sections and placed a different disinfectant in each section to test what would inhibit the growth of this particular bacteria. 

Thursday, November 7th

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Dear Blog and Blog Readers, 

Today in lab we learned how to take nasal swabs!

First, we obtained a sterile cotton swab and dipped it in sterile saline solution. The we inserted the tip into the nose and moved it in circles close to the opening of the nostril. 

Max is a little nervous. 

Rose swabbing Max's nose. 

After swabbing each other's noses we took a blood agar plate to and spread the swab on one corner of it and then incubated it at 37 degrees Celsius (human body temperature). This is a test to see if Staphylococcus aureus grows. Next class we will check to see who is infected. 

Tuesday, November 5th 2013

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Dear Blog and Blog Reader, 

Today we went to the water treatment plant! Enjoy some pictures of what we saw!

The drain over the stream of water in front of the plant as the water is being cleared of debris. 

The tank where the water goes through to be cleared of debris outside the plant. 

This is an old generator that is not used anymore. 

November 21st

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Dear Blog and Blog Readers, 

Woohoo! We finally determined what type of bacteria we have! It's called "Serratia marcescens." What finally gave its true identity away is the red pigment. And due to the fact that none of the other types of bacteria are red . . . we could have identified our bacteria right away! Unfortunately though, we didn't know this until the end.

Here, we are examining a bacteria sample that has conveniently decided to reside on the cabinet door! We examined its many features in order to determine its true identity.

Today, we also made yogurt in class. We did this by placing a little bit of yogurt in milk. We then allowed the milk to sit as the enzymes in the yogurt converted the rest of the milk into more, and more yogurt. However, this is only done with greek yogurt.

Sample #1

Sample #2

The only antibiotic our bacteria was resisted by was neomycin, and aminoglycoside. Interestingly enough, erythromycin inhibited the pigment in our bacteria but not the bacterial growth itself. 

November 19th

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Dear Blog and Blog Readers, 


We checked the final agar plate filled with bacteria grown from a swab of a sink handle to see what disinfectant was most effective. Soap, lysol, lysol wipes, and hand sanitizer were tested. 

The whole plate.

The hand sanitizer did not kill very much bacteria at all!

This was mislabeled wipe--it's actually spray--which killed some bacteria.

This was mislabeled spray--it's actually the wipe-- which inhibited the growth of a lot of bacteria!

The soap inhibited the growth of some bacteria.

And the winner is.....


Lysol wipes!

Lysol wipes actually inhibited the most bacterial growth, interestingly enough! So the next time you're going to to go to clean the bathroom, be sure you ditch the spray and soap and use lysol wipes!

We also performed the last test needed to discover our bacteria...antibiotic testing! We inoculated a spread plate with bacteria S and separated it into 5 sections. We then placed different antibiotic disks on each section and placed it in the 25 degree incubator. Next class we will see what kills our bacteria!

Here is the list of antibiotics we could choose from to test with. 

We decided to use novobiocin, erythromycin, an aminoglycoside which was neomycin, tetracycline, and penicillin. 

Sam creating the spread plate.

Max placing the antibiotic circles on the plate.

The final spread plate!

Check back next time to see which antibiotic was most effective!

Thursday, October 24, 2013

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Dear Blog and Blog Readers, 

Last week:

We made several plates to test different qualities of our bacteria:

Here are the results of the following tests:

Thioglycolate: 

Since there was pink at the top and throughout this indicated that the bacteria uses oxygen but can not use oxygen as well this bacteria is facultative. 

DNASE:

This test is to see if this bacteria secretes DNase which hydrolyzes linkages between nucleotides in DNA. Therefore, if the bacteria secretes this enzyme, the DNA will be left in small fragments. For this test to be positive a clear zone after 1N HCL was flooded onto the plate. On our plate there was no clear area and therefore this test was negative and S does not secrete DNase.

EMB:

EMB is a selective medium that inhibits gram-positive bacteria, is used for identifying enteric bacilli, and is a differential medium used to distinguish between those that ferment lactose and/or sucrose and those that don't. If the bacteria ferment lactose then they will produce acid which will cause the dyes to get into the colonies. This results in dark blue colonies. When acid production is lower pink colonies will result. Since we had bacteria growing the bacteria is gram negative and since it is pink is slightly ferments lactose and sucrose. 

MacConkey Agar:

This plate is used to distinguish between gram negative and positive bacteria. Our bacteria is growing and therefore our bacteria is gram negative since it inhibits gram positive bacteria. When the color is red or pink it indicates that the bacteria ferments lactose, which it is evident that S does ferment lactose from this test. 

Mannitol Salt Agar:

Mannitol Salt Agar tests is the bacteria is a halophile (able to live in very salty environments). S did not grow at all and therefore is not a halophile and the test is negative

Phenylethyl Alcohol Agar:

The PEA Agar tests inhibits gram negative bacteria and our bacteria didn't grow, therefore our bacteria is gram negative. 

Blood Agar Plate:

Here, there is beta hemolysis  which indicates partial hemolysis because there is a greenish hue around the colony.