Biol 251 - Microbiology Lab

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Microbiology Case Study Overview

This experiment is designed to emulate a clinical setting. It follows the traditional medical teaching technique of using a case study to test and develop your knowledge of the subject matter and your ability to use that knowledge to problem solve. You will be given a scenario of patientís symptoms. Your job is to determine what microorganism is causing the patientís symptoms. The tube you are given represents the patientís lab sample. It is your job to isolate the two organisms. You must determine which is the pathogen, the causative agent, and which is the common bacterial contaminate found at that site.You must also determine which antibiotics available to you will be the most effective in treating the patient.

The procedure you are following is very similiar to what would happen with a sample in a clinical lab. The anerobic testing is included to introduce you to the various aerotolerances of microorganisms. This step would most likely only be performed if an anaerobic organism was the suspected pathogen.

We have provided this information in a variety of formats to help you understand the case study procedure.

Clinical Case Study Scenario with Patient Assessment Forms

Mongolia Case Study Files

Day 1

  1. You must first read the scenario establishing conditions under which you will be working. Case studies assigned and handed out.
  2. Start filling out the diagnosis information form.
  3. Unknown organisms handed out. Each pair receives 1 tube with two organisms in it.
  4. Begin isolation by streaking 1 TSA plate and 1 blood agar plate. You will incubate the blood agar in the CO2 incubator in case you have a Strep. The enriched CO2 atmosphere enhances the growth of most strep organisms. You will incubate the TSA plate in a regular incubator.
  5. Gram stain your sample. Be sure to include your gram positive and negative controls. More than one group of students have gone off on the wrong path because they neglected to do this.

Day 2

  1. Continue isolation. Hopefully you can tell your organisms apart from their morphology or responses on blood agar. You will probably need to look very carefully. It is a good idea to verify your choices with your instructor or IA. Streak each organism on a separate plate to obtain a separate pure subculture of each. Label your two organisms very carefully.
  2. Gram stain from your isolates (if separated). You may be able to determine if they are Strep, Staph or Gram negative enterics.
  3. Using the gram stain information, the symptoms in the case study, your text book, and reference materials in the lab, list the possible pathogens that could be responsible for your patient.
  4. Make a flow chart of how you intend to identify the suspected pathogen, which tests you need to do and when.†Use the flow chart provided as a model.
  5. Show this to your instructor or IA for approval before proceeding.
  6. If both organisms are not separated with pure cultures growing on stock plates, re-streak until they are.

Day 3

  1. You may begin your tests today if you have both organisms separated with pure cultures growing on stock plates, and you get approval. You will do a motility test and an FTM anaerobe tube for each organism to help characterize it. The other tests you do should be specific for the type of organism you suspect you have.
  2. Fill out a materials sheet indicating exactly which tests you will need.
  3. Show this to your instructor or IA for approval before proceeding.
  4. If both organisms are not separated with pure cultures growing on stock plates, re-streak until they are. Do NOT begin tests until you have pure cultures!

Day 4 - ?

  1. Continue your tests on both your suspected pathogen and your contaminate.
  2. Conduct an antibiotic sensitivity test on your causative organism, once you have identified it.
  3. Be sure to accurately record your lab activities directly into your lab book.

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