I work in a microbiology lab in a hospital. We do testing for Salmonella, Shigella, Campylobacter, and other pathogens that cause diarrhea and other intestinal symptoms.
It will take 24-72 hours for the stool culture to be completed. Sorry, but that’s the way God created bacteria. They need time to grow.
A stool culture may even take longer, because there is a lot of normal stool flora that often overgrows the pathogens, and the pathogens will need to be isolated before they can be tested. That takes an additional 24 hours or more. Sorry again.
In addition, any cases of Salmonella need to be confirmed by your state lab. So you will receive a report of “presumptive” Salmonella.
There are DNA probes that can be used, but most local hospitals don’t have them for Salmonella testing. If this gets big enough, CDC might ask all local labs to send their stool specimens to facilities that have DNA probes. But these cost a LOT, and since many of the patients involved are on public aid, there will be no reimbursement to the labs for this testing. I realize that when your child is involved, you say, “Cost is no object!” But it is an object; someone has to pay the lab techs like me, and pay for all the overhead in the lab. Sorry for the third time.
So unfortunately, you just have to wait for the cultures to grow. At least Salmonella usually passes without causing great suffering, permanent harm, or death.