We found a donor via acquaintances, and screened him through both a comprehensive questionnaire(almost any kind of chronic health issue is bad) and blood&stool

We found a donor via acquaintances, and screened him through both a comprehensive questionnaire(almost any kind of chronic health issue is bad) and blood&stool testing. While there's some risk of transmitting dangerous, asymptomatic-in-host pathogens, if you rule out viruses and the worst of bacteria, a healthy person's microbiome is likely to be robust enough to ensure they don't proliferate.