Clinical Case Problem-Solving

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Clinical Case Problem-Solving

What you get out of the clinical cases is totally dependent on what you put in!

The cases are presented by organ systems as this is the way you will be experiencing medical microbiology in real life.

The cases have been chosen to represent typical presentations of infections due to some of the most commonly encountered microbial pathogens in U.S. hospitals (you won’t get Ebola!)

The cases are presented as “unknowns” and are designed to guide your acquisition of knowledge in several broad areas:

1. general understanding of the normal functioning of the system

2. the names and characteristics of the pathogens that might be encountered in that system, specifically the pathogen on which the case is based.

3. clinical characteristics and pathology of a specific agent - emphasis

4. the relationship of the microbe’s “life-style” and virulence factors and the patient’s immune response to the clinical presentation of the disease- emphasis

5. laboratory procedures for handling of samples from the different systems

One case will be assigned to each group each week. The cases will vary in complexity and in how much the group will be required to do with the cases. The cases will require work outside of class time. Cases will be accompanied by a clinical sample from which you, as a team, will attempt to isolate the causative agent. You will have class time available to meet as a group to coordinate your laboratory activities and to discuss the cases. The real power in team, problem-based learning comes when you teach each other! You will learn most thoroughly and retain longer if you really think about how best to explain to someone else.

Your time will be less structured during this period of study, you will have to allocate your time wisely to be sure that you are putting in sufficient time each week to learn the necessary material. In addition to a case grade given on the write-up that will be given to all members of the group, there will be a quiz every Monday that you will take as an individual, so it is important that every member of the group participate fully in resolving the clinical cases and know the information for the quizzes, and for the final.

Structure for presentation and completion of cases

1. Mon. During regular lecture time. - introduction to the organ system, and distribution of cases. Everyone should attend.

2. Mon. During regular lab time - continuation of any lecture material as needed, short pre-lab discussion of any new laboratory techniques; clinical samples and accompanying demonstrations will be available in the laboratory and you may pick up a clinical sample AFTER you have a presumptive diagnosis and a differential list, and have decided what clinical sample should be collected and what you will do with it in the laboratory. Everyone should attend.

3. Tues. sometime. Someone(s) will need to evaluate the inoculated plates and subculture and/or inoculate biochemical tests if appropriate.

4. Wed. Time for you to meet as groups, we will not meet for lecture. Continue lab work up.

5. The group will probably want to schedule an additional meeting time toward the end of the week to coordinate the writing and proof-reading of the case report.

6. One written report from each group will be due the following Mon. (specifics on write-ups below). You should take turns being responsible for the write-up.

7. On Mon. there will be a short quiz at the beginning of lecture concerning the system covered the previous week, before we begin discussion of the next system.

Organizing Laboratory Identification

1. Mon. - receive sample, perform direct smears and plate on primary media. Plate samples immediately, resist the temptation to set it aside until later in the day and do NOT refrigerate sample before inoculating primary media! Your pathogen may die out. Several different primary plating media will be available. After consulting the primary plating chart in your lab manual, use only the most appropriate media for your sample. Remember that in real life you need to balance cost, efficiency, and accuracy.

2. Tues. sometime - someone(s) in the group will need to transfer the isolate to fresh media and/or inoculate diagnostic tests - DO NOT put this off until Wed. or the pathogen may die and you won’t get an identification.

3. Rest of the week. Proceed in an organized and logical manner until the desired level of identification has been determined (I will let you know how far I expect you to be able to take the identification, i.e., do you need to identify the species or is genus good enough). Work out among yourselves who will do what when.

4. After your pathogen has been identified, be sure that you have appropriately discarded plates and tubes and that nothing is left in the incubator or refrigerator. You will lose points if you leave a mess for me to clean up.

What to do in your groups

Each case will generate questions for the group to answer. There are (at least) two approaches you can take to working on these questions.

A. Everyone researches every question. Then you meet as a group to discuss your findings, identify the most important material, summarize your findings, and decide what other information should be gathered.

B. The questions are divided among the group members. Each member researches their assigned questions and then “teaches” this information to the rest of the group.

C. In either approach, it is the talking about the material out loud to each other that is critical – do not skip this most important element or you will short change your own learning!

All group members are responsible for all aspects of the case and for details on how the pathogen was identified in the lab.

Grading

Correct identification of the causative agent is only a part of the grade. I want to see that you understand the system and how the pathogen caused disease in the particular case. I want to see problem-solving in action, so logical progression of thought is more important than a correct species identification (i.e., don't try to fake your results hoping that it will result in a better grade).

As a group you will turn in one case report per case. Each member of the group will receive the same grade.

What goes in the reports?

1. Do not write a separate cover page - on the top right of the first page write the names of the team members and put an astrix next to the name of the primary writer. Title with the case number and system. Example - Case One–Upper Respiratory Tract.

2. A brief summary, in your own words of the major features in the clinical presentation of the case and important test results; this is done to simulate a "Grand Rounds" experience.

3. Main Body of Paper - A discussion of the pathogen isolated. I will want to know:

a) what is the presumptive diagnosis? A presumptive diagnosis describes, in clinical terms, what you believe the disease or syndrome is at the beginning of the investigation, e.g., acute bacterial pneumonia, acute pharyngitis, infectious mononucleosis, tuberculosis, etc. For some cases there may be more than one presumptive diagnosis (ex. influenza or pneumonia). In this case list them in order of suspicion if possible and appropriate.

b) what is your differential list? A list of specific organisms you suspect would be involved in the presumptive diagnosis, at the beginning of the case just from the clinical presentation, before you do any lab work. Rank your list, from agents you consider most likely to agents you consider not very likely, but still possible.

c) Is there a most likely culprit? a rule out (R/O)? if so, what is it and why is it most likely? Sometimes there is a particular, single organism that is most frequently associated with a condition, e.g., E. coli and urinary tract infections. Give an explanation for why you select or don’t select a most likely agent.

d) Your final differential diagnosis (Differential diagnosis - “Determination of which one of two or more diseases or conditions a patient is suffering from by systematically comparing and contrasting results of diagnostic measures.”) and the identification of the pathogen (genus and species when possible, written in correct scientific format) and its characteristics. If the pathogen is a bacterium I also want to see here 1) Gram reaction, 2) cellular morphology, and 3) either catalase or oxidase results. If the pathogen is a virus I want to know 1) whether or not it is enveloped and 2) its nucleic acid type. Ex. Escherichia coli, an oxidase negative Gram negative rod. Influenza, an enveloped RNA virus.

e) Anything significant in the patient’s history that predisposes them to infection with this particular pathogen. (There may or may not be any particular predisposing factor).

***f) a thorough discussion relating both the virulence properties of the pathogen and the host defenses to the pathogen to the clinical picture described in this case. Everything written in your own words – be extremely careful not to plagiarize your references; be particularly careful with internet sources. Start with the normal habitat of the pathogen and how the patient acquired the pathogen (route of transmission), host immune defensesat site ofentry, virulence factors the pathogen uses to establish at the site and/or evade immune detection or destruction, and how finally how the pathogen or the immune response to the pathogen produces the clinical signs and symptoms. Organize your presentation sequentially; think logically about how the pathogen establishes in the host, moves through the host, what it encounters along the way, and how damage to the host occurs. I want you to account specifically for each and every one of the signs and symptoms the patient presents with, including signs found during laboratory tests. These paragraphs are the heart of the report and will be worth a considerable number of points! Please bold each host defense mechanism and pathogen virulence factor, and bolditalicize each clinical sign and symptom you discuss to make it easier for me to see that you hit all the critical points.

It is easier for me to grade write-ups if you label each paragraph with the appropriate letters a-f. Easier for me to grade means a faster turn around time for you.

4. Answers to any additional questions posed about the case.

5. References consulted; and referenced appropriately in the body of the text. You need a minimum of three outside references (outside means in addition to class notes, your text, or the lab manual). References consulted should be internal medical or advanced microbiology books or research articles, not an introductory microbiology text. Some internet sites are appropriate, such as CDC, NIAID, WHO,web sites from medical schools or from academic research labs. But be careful! There is a lot of non-refereed web information out there; the majority of your references need to be books or professional articles and NOT internet sites. Do not put information in quotations. Use of quoted material says to me that you did not understand what you were reading well enough to put it in your own words.

6. On a separate page - For cases accompanied by clinical samples, a one-page flow diagram showing me exactly how you worked up your clinical sample; beginning with what type of specimen it was, direct observations of specimen, what media it was plated onto, what the growth looked like on each media, which colony morphologies were selected for further work up, etc., and ending with the identification of the causative agent.

7. A written overview of the lab work. Discuss anything that went wrong in the lab work-up, any mistakes that were made or contradictory lab results.

8. Your guarantee that you cleaned up after yourselves in lab (nothing left in incubator or refrigerator), and I will check on Saturday each week.

Someone will have to write the reports (1 report for each case). If your group decides to rotate this task, be aware that everyone is still equally responsible, for better or worse, for what is turned in; each member should have an opportunity to read the report and make suggestions before it is turned in for a grade. An excellent way to do this is to write your reports in Microsoft Word, send the drafts by email to all of your team mates, and ask them to edit using the Track Changes function (toolbar: Tools: Track Changes – or in newer versions – toolbar: Review: Track Changes). Warning - if the writer makes serious errors or commits plagiarism, the entire group is responsible. Reports need to be type-written or computer generated. Writer will submit the report in their manila folder.