Sorry to hear you are finding the case study assignment by our software to be an issue. The case studies were written based on the natural environments and medical presence of the microbe and only later linked to an organ system. One of our intents in our case studies was to introduce the concept of secondary infections and the spread of infections from the original site to other regions of the body. We talk about such things often in lecture with a good example being Streptococcus pyogenes - first strep throat, then scarlet fever, then rheumatic fever/heart murmurs, or kidney issues (glomerulonephritis). It might seem odd to encounter a throat bacterium in a discussion about kidneys or hearts, but we felt such things were appropriate. Our thought was that sometimes the microbe you find is not what you expect to find as per the "textbook" and so we wanted students to be ready to think outside the box. So, in some cases the causative microbes are the exception rather than the rule for that organ system. So, it may appear the assigned organisms are not always the expected ones for an organ system, but we don’t believe any are totally off target. Add to this that many pathogens are also environmental isolates (as described in Bergey’s), and you have an even broader range of scenarios for microbes to consider.
Our case studies are based on the organism. We have a database that assigns the microbe based on its potential to fit the subgroup (like an organ system disease), and we have a second database that then assigns a case study appropriate to the microbe. Case studies were written to expand the utility of the software beyond medical applications, and so it is possible a medical microbe would have an environmental case study when that microbe could be appropriate for either scenario. This is the source of the occasional odd case study related to a medically-related activity. Activity and subgroup determines the microbe, microbe determines the case study, and the result can be case studies twice removed from the subgroup the student is working on.
My recommendation to instructors is to use the free software Admin Console (if you are a registered instructor, you can find it and instructional videos here) to assign case studies for your students. You can assign the microbe and case study from all available to insure your students get the content you want for them. It will allow you to give all students the same unknown and case study (which some schools really like to do), or you can assign to individuals their own specific unknowns and case studies you feel are most appropriate to the topic, drawing from all 120+ microbes and 200+ case studies. I believe Admin Console allows instructors to preview the case studies (identified by their case study #) before selecting one for the student(s). If that feature is not available yet, let me know and we will find a way to get the content of all case studies to you so you can determine which ones you want to assign. We have not at this point added the ability to allow instructors to construct their own case studies and add them to the database, though that may come in the future. If you do not want to use the Admin Console, an alternate approach might be for you to assign the unknowns you feel are most appropriate for the topic and then email students the case study you want them to use (or create your own) for the work on their assigned microbe.
Students - if your instructor does not use Admin Console, you will be receiving a randomly assigned unknown appropriate for the subgroup (such as Nervous System, etc.). The microbe's lifestyle may include many other environments besides a nervous system infection, meaning you may get a case study not entirely fitting the assignment. If this is the case, my suggestion is that you can always create more unknowns for that subgroup and lab activity, each time getting another randomly assigned case study, until you get one fitting the lab activity and assignment. Use that one!