Antibiotic Lab

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Bacteria and Antibiotic Lab Report The purpose of this lab was to identify the possible bacteria discovered in two patients and to test different antibiotics on the bacteria to find the best treatment for each patient. In order to identify the bacteria, we had to Gram stain the bacteria from culture A and the bacteria from culture B, and then observe the bacteria under a microscope. We recorded the shape and color of the bacteria in order to find a possible match with a strand of bacteria. If a bacteria appears blue-purple after staining, it is a Gram-positive bacteria; if a bacteria appears pink after staining, it is a Gram-negative bacteria. By identifying the shape and morphology of a bacteria, we are able to see the possible strand of…show more content…
The reason that the bacteria in culture A was stained pink during the staining process was due to the pink staining of the safranin on the bacteria after the decolorizer removed the outer cell membrane (the lipopolysaccharide layer) that contained the crystal violet-iodide complex. Once we inspected culture A under a light microscope, we were able to see that the bacteria was rod-shaped, so it was a bacilli. A popular Gram-negative bacilli bacteria in a children’s ward is Escherichia coli, so that is what we suspect the bacteria in culture A to be. We discovered that the bacteria in culture B was Gram-positive due to the blue-purple coloring of the bacteria after the Gram staining. The reason that bacteria in culture B were stained blue-purple during the staining process was due to the crystal violet-iodide complex not being able to be stripped from the bacteria during the decolorizer process. This means that the bacteria in culture B contained complex structure of peptidoglycan that form a thick enough cell wall to not be affected by the color stripper, meaning it was Gram-positive. Once viewed under the microscope, the bacteria appeared to be round meaning the bacteria were cocci. A popular Gram-positive cocci bacteria in a children’s ward is Streptococcus aureus, so that is was we suspect the bacteria in culture B to
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