Thanks for the info on Mutaflor. I think this might be a really good lead. I checked through the clinical trials and have listed the ones I found interesting below.
I could not find direct evidence that strain Nissle 1917 E.Coli (Mutaflor) will necessarily inhibit Streptococcus overgrowth, but since both are small intestine bacteria it might occur due simply to competition. Maybe the E.Coli will also protect my epithelial cells against Streptococci and thereby protect/repair my leaky bowel. That Mutaflor reduces gas/bloating also suggests inhibition of gas producing bacteria (Streptococci?).
Even if I need to address the Streptococcus issue separately, supplementing Nissle 1917 E.Coli may be very beneficial of itself. Other good news is that lauricidin should not kill it, so I may be able to take both together.
I am also looking at the option of taking Vancomycin for 10 days just to determine whether killing off my supposed Strep/Staph/Clostridium overgrowth makes a big difference. They are all gram positive so I should get a good kill. Somewhat reluctant to take Vanco for obvious reasons though.