Kefir does not have the strep bacteria strain in it and it is a super-powerful probiotic. if you have a dairy or casein problem, you can buy coconut milk w/ kefir strain. it is also fairly easy to make yourself. that way you can be sure of the bacteria used and use any type of "milk." My son used to react to yogurts, but they also tend to have lots of sugar, so it is hard to tell what the reaction is to.