When some people hear the word ‘Streptococcus', they may automatically cringe, thinking of Strep Throat. But Strep Throat comes from Streptococcus pyogenes, rather than Streptococcus thermophilus, which is a friendly transient bacteria.
To analogize: we know all cats, big & small, come from the genus Felis. Though they are closely related, we can easily see major differences between tigers—ferocious predators—and the finicky cat that shares our couch, who turn up their noses at certain brands of cat food. Thus they are narrowed down to species, to better understand who and what they are.
Same with probiotics. Streptococcus thermophilus (aka Streptococcus salivarius subsp. thermophilus), when paired with Lactobacillus Bulgaricus, is used to make yogurt. Different species, different results. One major advantage brought forth by Streptococcus thermophilus is that of improved gastrointestinal rhythms. This strain is found in most human & pet probiotics. Rest assured that Streptococcus thermophilus is safe for consumption.