Wow, I'm probably the most qualified besides our Doctor friends to answer this question. You could probably use them together. Streptomycin Sulfate is made from Streptomyces griseus. It is used against Gram negative bacteria. Streptomyces lydicus is gram positive.
Probably ok to use together. Always exceptions to any rule, but it looks good. Streptomyces lydicus also can produce antibiotics. So I would say go for it. I myself use it on my tomatoes. Streptomyces lydicus that is.

I'm not sure it would help for next year, but enough is in the package to use it this year and next, you don't use that much. It can't hurt, and could help. I just sprayed some a week ago on my peppers, tomatoes, and fruit trees. For how wet a spring we are having I'm seeing no fungus, I can't say this is the sole reason, but it is in my arsenal of weapons, and if it ain't broke, don't fix it.
I know you probably want it for bacteria, but hey fire blight is gram negative, go for it!

This post was edited by Drew51 on Wed, Jun 25, 14 at 14:34

Drew, thank you. I do want it for fire blight. I never thought I'd have to worry about it but the weather the last few years has been so erratic. I knew someone here would know about the details:)

It's a good idea to hit them on various fronts. Also prevents pathogens from adapting. Since products are from the same genus, I'm 99% sure that the actinovate bacteria will not die.