Soraya Pashaei-MarandiBio 111-5437 October 2015Assignment #5-Cell Case StudyBackground:In order to classify a bacteria, the chemical and physical properties of their cell walls are taken into consideration. A Gram’s stain test is conducted to test whether a bacteria is Gram-positive or Gram-negative. Gram-positive bacterias have a complex network of amino sugars that form a cell wall. For this type of bacteria the test results will come back as blue-purple. On the other hand, Gram-negative bacterias have a cell wall with less peptidoglycan and their test results ap-pear to be pink. Broad-spectrum antibiotics target both Gram-positive and Gram-negative bacte-ria, while narrow-spectrum antibiotics target either or. Results:For this cell case study, a sample A bacteria and a Sample B bacteria were placed on separate microscope slides. They were then each stained with crystal violet and the crystal violet was then trapped with iodide solution. To decolorize the samples, alcohol was poured onto the slides. They were then counterstained with safranin in order for Gram-negative bacteria to ap-pear a pink color. Each slide was observed under a 100x objective microscope. Culture A ap-peared to be pink with a bacillus shape(Escherichia coli). This meant that Culture A of Mary Farmer was a Gram-negative bacteria. Culture B appeared to be a blue-purple color with a coc-cus shape(Streptococcus aureus). This meant that Culture B of Brian Evans was a Gram-posi-tive bacteria. The next step was to observe the sample of antibiotics and measure the zones of bacterial inhibition. These zones would be where there were clear circles around the antibiotic disk. The results varied among the different antibiotics and the different cultures. Some antibi-otics were more resistant to the bacteria, and therefore would not be a reasonable treatment for the patients. For Mary Farmer(Culture A), she should be prescribed Nalidixic Acid because it was the antibiotic that was most sensitive to Culture A. For Brian Evans(Culture B), he should beprescribed Penicillin because it was the antibiotic that was the least resistant. Some miscon-strued results could come from leaving the alcohol on the slide too long which would strip the Gram-positive bacteria cells. Another problem could arise from having too many cells of the bac-teria placed on the slide because it becomes difficult to view the result under the microscope. Questions:1) The most effective antibiotic for Culture A was Nalidixic Acid.2) The most effective antibiotic for Culture B was Penicillin.3) Both children do not have the same infection considering the Gram’s stain, bacteria shapes, and the antibiotic test results.4) Bacteria A came back with a Gram negative test result and Bacteria B came back with a Gram positive test result.5) Neither patient would be infected with more than one strain.6) Not all the bacterias were resistant to antibiotics, however, some were. 7) I suggest Dr. Fields prescribes Mary Farmer Nalidixic Acid as treatment. He should then pre-scribe Brian Evans
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