A patient presents to the clinic and is diagnosed with an infection. A nurse practitioner takes a swab of the infected area and sends the sample to the lab to be analyzed.
Because of the current pandemic, staffing in your clinical microbiology lab has been affected. Your staff performs the necessary steps for isolation and finds that the infection involved two bacterial organisms. They document, with pictures, each step of their isolation, agar plate growth, gram stain, and pure culturing process. Additionally, they perform appropriate biochemical tests as well as Kirby Bauer susceptibility tests, and take pictures for the official record of those results.
You, their manager, are working from home, and tasked with overseeing their work, as well as using their information to determine the identity of the organisms in question causing the patient infection, as well as the best antibiotics for use.
You will receive a PDF presentation with the unknown patient number. It will contain pictures that are representative of all the steps and observations that would need to be performed to isolate and identify two species from the same culture (patient clinical mixed polymicrobial specimen) as done by your staff. You will record the observations for both gram positive and gram negative organisms. Then, with the provided flowchart, you will determine the identity of both species. Finally, you will observe and interpret the Kirby-Bauer susceptibility results for both species, so that appropriate antibiotics may be prescribed to the patient.
Procedures:
- Receive your powerpoint that has images of each step of isolation and species determination, including:
- Images of dilution streak plate technique performed on an initial set of plates with the mixed specimen: TSA, PEA, and MacConkey media. Your images may also contain TSA blood agar or mannitol salt agar (MSA) result
- Images of the Gram stain of the mixed specimen.
- Images of pure subculture plates prepared for each organism.
- Images of the gram stains performed of each presumptive pure culture.
- Close up images of colony morphology of each subculture.
- Images of the results of biochemical tests performed on each organism.
- Images of the results of the kirby bauer test.
- Begin recording observations for BOTH ORGANISMS on the Unknown Form. Record the appropriate notations according to each test as found in Lab 9 and other prior labs. Recording color or a short description is also advised. Use the Unknown Form to organize your information. Any tests or results you have images for must be recorded. There will be some tests that you will leave blank if you are not given images or data.
- Use the posted Flow Charts (dichotomous keys) to determine the identity of your gram + and gram – organism. Be sure to use the correct flow chart for each organism. Do not use flow charts found anywhere else, and do not use resources elsewhere to confirm reactions on the flowchart. Some species identifying names with their reactions have been changed from established research.
- Record the Kirby Bauer Antibiotic Sensitivity results in the Unknown Form. Images of plate(s) and measurements will be provided.
- Interpret the sensitivity results using the provided chart of standards included with the Flow charts, and record results in the Unknown Form.
Once the identity of each organism has been obtained, a complete Unknown Report must be prepared according to the guidelines to thoroughly communicate your observations and results of isolation, pure culturing, biochemical testing, and KB tests.
This Unknown Report will be turned in using a Turnitin link in this module.
FIRST TWO ATTACHED ARE FOR THE FOLLOWING BELOW
BE SURE TO REVIEW ALL VIDEOS AND INFORMATION IN LAB 9 BEFORE BEGINNING YOUR UNKNOWN PROJECT!
You should have your unknown PDF file sent to you or made available to you by your instructor. Check your email or announcements for instructions. It will include images that guide you through the isolation of your organisms from a mixed sample, gram stains and images of media used in isolation, and biochemical test result images.
After you receive your Unknown file, you will record what you find from the data and images, and keep it organized using the Unknown Form. You will be required to turn in a copy of the Unknown Form by attaching it to your report. You may fill it in electronically, or by hand. If you fill it in by hand, you will need to scan it or take a picture of it when completed, and insert it into your unknown report. Make sure you refer to previous labs for the proper notations for each test. You will also include a brief note about a color or reaction you visibly see for each item, if applicable. Do not elaborate or go into details about your interpretation on the Form (instead, do so in the discussion of your Report).
Once all your observations are recorded properly, use the attached copy of the Flowchart to help you determine your unknown organisms identities. The Antibiotic Susceptibility Chart is also there.Help with learning Lab 9, preparation for completing the project and studying:
A document you can download to build flashcards for all the media and biochemical tests we’ve learned about is attached to this page. If you refer to these flashcards that you make while doing your project, you can get through it faster, and have a resource you can study for lab exam 3. These are NOT completed cards – use this page to know what to include on your cards.
Help with learning how to read the flowchart or dichotomous key:
Download the document here to get some practice using our flowcharts using data from biochemical tests. The answers to these scenarios are on the last page.
OTHER HELPFUL NOTES for the UNKNOWN:
Your organisms: you have exactly one gram positive, and one gram negative organism in your mix (A and B).
Nitrate results: Often, the first step in evaluating the nitrate test is simply looking at the durham tube for the production of gas. This tells you definitively what result you have, and nitrate A and B do not need to be added.
Some of the pictures in your file – the first few pictures in the presentation represent inoculation done with the mixed culture that had both organisms (A&B) on various types of media. Use these to help you determine (with other clues) which organism is your G+ (A or B), and which organism is your G- (A or B).
To determine your organism: ONLY USE THE POSTED FLOWCHART IN THE LAB 9 AREA TO DETERMINE WHAT YOUR ORGANISM’S IDENTITIES ARE! DON’T USE ANYTHING ELSE!
Report forms: Your forms, where you can succinctly record the results of the tests you’ve been provided, need not have any information about test you weren’t given in your file. The forms should also have more than just +/- filled in the blanks or yes/no. Record colors or reactions that you see too. You CAN print them and fill them in by hand, and attach them as pictures in your report (or as screenshots). Regardless, they MUST be large and legible to grade.
Discussion: Your discussion section for your G+ and G- organism MUST be typed, and should be separate for your G+ and G-. Be specific and thorough about the isolation steps that appear to have been performed on selective/differential media, and about the interpretation of the biochemical tests in your report (including what they MEAN).
https://drive.google.com/drive/mobile/folders/15JIJrPEgNN2wScEilTfT_koivuhYi8v4?usp=sharing&fromMobile=true
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