Ditto cadence's advice... biggest risk is infection and on that note, in addition to what cadence says about vaccination, I would say have you both checked for Hep infections and parasites on a regular basis (and if any come up positive, stop immediately any scat).

E.coli is not all that dangerous unless it is a specific strain of antibiotic resistant E.coli. It mostly lives in your gut and on your skin and is relatively harmless (compared to some far more pathogenic bugs out there).

Not sure about this but you may make a big difference to your risk of parasite and bacterial infection by swilling your mouth out afterwards with an antibacterial mouthwash. Though if you are actually swallowing this won't help much...