Every time I write about this, I'm reminded of a segment on one of the news magazine shows like 20/20. They were talking about salmonella food poisioning and the importance of proper sanitary procedures to avoid it. They took some chicken and coated it with an invisible dye that would glow under black light. They gave it to a woman to prepare for dinner and then traced the dye to show how easily it could spread to other areas.
The woman prepared the chicken and promptly returned it to the refrigerator and washed her hands. She then prepared the rest of the meal. When she was finished, they checked the kitchen for cross contamination of the dye which would show how bacteria could spread.
The first place was the handle on the refrigerator door and next was the handles on the faucet on the sink that was contaminated when she washed her hands. Of course, when she turned the water off, she re-contaminated herself and then spread the contamination to the hand towel she used to dry her hands. She had also contaminated the spice jars holding the spice used on the chicken, the cooking oil bottle, the knife handle, etc. They showed that the proper way to do it was to put the chicken in a container, wash her hands, put the lid on the container and then put it into the refrigerator. That stopped the contamination dead in it's tracks until she was ready to cook it when she dumped it in the pan and moved it around with a fork. Stopped again! Doing it the proper way stopped the contamination in it's tracks and the cooking process killed any bacteria on the chicken.
You have to think this way when you are battling one of these easily transported bacterial infections. First, look for the original source of the infection. Prime candidates are other family members and pets. Even though they may not be showing any symptoms, they can be carriers of the infection and mostly, proper hand washing procedures are the easiest and best way to stop the infection. Other candidates are day care and doctor's offices and places where your son may visit. Think about how the infection can spread around your home and get to your son. Frequent changes of bed linens, wash cloths towels and clothing is a must. Wash them in hot water and use regular or color bleach. (Especially diapers!) Also wipe all surfaces your son will touch every day. Spray cleaners are good but a mix of bleach and water is even better. You can mix about 4 parts water with one part bleach and keep it handy in a spray bottle. Especially clean toys, cribs, playpens, strollers and such often. This should be continued for at least a few days longer than a prescription for antibiotics which in most cases would mean 2-2 2/2 weeks.
Following this routine, you will eliminate the vast majority of the bacteria so that your son's immune system will not get a massive dose that will overwhelm it. Eventually, his immune system will develop to the point that he will resist these infections quite easily in the vast majority of cases.
Good luck in getting rid of these critters!