Q: My villain is a cook and he wants to kill the hero by feeding him tainted food. I want to avoid using a detectable poison, so I thought a deliberately introduced food-borne pathogen, such as ptomaine, botulism, E.coli, or salmonella, or something like those, would do it. But how do I get the bacteria/germs/whatever in the food? What will it do to him? How long would it take him to die, and what steps could the hero take to make sure he survives? What could the villain do to make sure the hero dies?
E. Coli Growing on a Culture Plate
A: This scenario will work but there are a few problems with it. First of all, using bacteria for murder is extremely unpredictable and most killers prefer a more predictable method. Just because your villain feeds contaminated food to the victim it does not mean that he will die because contaminated food rarely kills people but rather merely makes them sick. Typically people survive these types of illness-but not always. The best way to assure, or at least increase the probability, that your victim would die is to prevent him from reaching medical care.
Infectious processes most often kill by two mechanisms. The first is that they alter the function of the infected organ. For example, pneumonia can kill by infecting the lungs and filling the air spaces with bacteria and liquids we call exudates. This is simply the body's reaction to the infection. Like a weeping wound or one that forms pus. This is what happens in the lungs and if so it interferes with the exchange of oxygen and the victim can die because the lungs fail. An infection in the kidneys can do the same thing by causing kidney failure and infection in the gastrointestinal tract, which is what would most frequently happen with ingested bacteria, can lead to severe diarrhea and dehydration or in some cases or severe bleeding and death can follow from shock.
But the most treacherous thing associated with any of these infections is the passage of the bacteria from the infected organ into the bloodstream. We call this sepsis or septicemia, big words that mean infection in the blood stream. When this happens the infection spreads rapidly throughout the body and very quickly the victim can suffer from septic shock-low blood pressure and shock from bacteria in the blood stream. This can lead to death in short order.
So regardless of which bacterium you decide to use, it would need to be added to the food and the victim ingest it. This would make him ill with gastrointestinal symptoms such as nausea, vomiting, diarrhea, abdominal pain, and perhaps bleeding in either the diarrhea or the vomiting. If untreated such an infection could then spread to the bloodstream and be deadly. But the key here is that he must be prevented from reaching medical help. Otherwise he would be treated and survive. But untreated his chance of survival is dramatically reduced. So you need to figure a way to prevent him from reaching medical care once he developed symptoms.
As for what bacteria to use, both ptomaine and botulism would be very difficult to come by. They are rare and your cook would have no access to this type of organism. He could of course damage a can of some food product and leave it sitting in a warm environment and hope that the right bacteria grew but most likely it would not be the bacterium that causes botulism. That's actually quite rare. So there would be no way for him to predict what organism would occur under that circumstance.
On the other hand, things such as E. coli, Salmonella, and Shigella are quite common causes of food-borne gastrointestinal illness. If your chef knew someone who was infected with one of these, perhaps from a recent trip to Mexico where these are not uncommonly encountered, he could then use this individual to supply the needed bacteria. How would he do this? The best way would be to obtain some stool from the infected individual. This could be from contaminated toilet paper or an un-flushed toilet. Gross but that's the way it is. This could then be placed into some food product and allowed to grow, which he could simply do a closet at home. He could then add some of this bacterial soup to the food product and in this way introduce a large amount of bacteria to the victim. Even better would be if he could find a way to inject this intravenously into the victim but that's not absolutely necessary.
Again, this would make the victim very ill with gastrointestinal symptoms. Then, as I said, you'll need to devise some scenario that prevents him from reaching medical help and if so he could easily die from sepsis.
There is an excellent non-fiction book in which a murder is committed exactly like this. It involves the murder of Joan Robinson Hill by her husband Dr. John Hill. It took place in the 1960s in Houston Texas and is an incredible story. The book is titled Blood and Money and was written by Tommy Thompson. If you can a copy of this it might help. Dr. Hill apparently grew bacteria in petri dishes at home and infected cream puffs to kill his wife. He then admitted her to a small hospital in the outskirts of Houston and he managed her care, which amounted to preventing her from getting adequate treatment since he did not offer her the treatment she needed. It became a huge and convoluted case that did indeed involved blood and money.