I have caught and owned probably thousands of Eastern Garters, as well as other species of Thamnophis, over the decades, and been bitten more times than I can even count, but I have NEVER, ever had a snake bite become infected, especially not one from one of the Natricine snakes, like Garters or Water Snakes. Snakes in this family actually are mildly venomous, and do possess a Duvernoy's gland, which is the evolutionary predecessor to a fully-developed venom gland, but their venom is very mild and has a poor delivery system, via grooved, enlarged "fangs" near the rear of the upper jaw. However, that venom does contain components which act as both a mild anticoagulant and an antibacterial. Bites bleed quite freely for a few minutes, in relation to the bite itself, which is barely felt, and these two seem to combine to inhibit infection. I get bitten out in the field most often, miles away from any soap and water or peroxide, and have never had a bite get infected. In fact, I don't know of any fellow snake keepers/field herpetologists who have, even with getting bitten while our arms are covered in mud and muck from a swamp!

Sharp-tailed Snake (Contia tenuis). Harmless slug eaters.

I assume that is a captive snake (or an escaped captive). While the pattern and coloration might first suggest that it is a striped morph California Kingsnake (Lampropeltis getula), the head shape and pattern tells a different story. The head shape looks to me like that of a milksnake (Lampropeltis triangulum). Therefore I am pretty sure this is one of the captive hybrids between a Cal King and a Milksnake.

The only poisonous snakes in Wisconsin will have a rattle at the end of their tails. Also, those are very very rare here. Also, snakes are your friends. They will keep rodent populations under control. They are generally very shy and won't bother you unless messed with, or stepped on (do not try to pick up).