Without getting all technical, snake bites, as any other animal bite may not be completely harmless. Even if the bite is from a non-venomous snake species, the bite can still carry bacteria and transfer it with the bite. Any snake bite should be dealt with by a doctor or vet (if a pet has been bitten) even if you know the snake is not venomous.
In terms of bacteria.. bites from known harmless snakes are the least type of bite to worry about..they are pinpricks that rarely bleed if at all (some exceptions are water snakes and garter snakes due to anti-coagulants in their saliva which thin the blood and allow you bleed more freely and also leaves the area itchy for several minutes). Wash the site with soap and water and you are good to go.
People generally have more problems getting infections from paper cuts, bites from their pet hamster, or scratches from their cat or dog and that is after having cleaned the wound out. I have never gotten an infection from a snake bite - even when left untreated...and I have been bitten by fresh wild caught snakes and captive bred pet snakes of all sizes.... from just hatched tiny babies up to a large 9 foot long burmese python (teeth size on him was just over 1/4"). Usually, a few hours after a bite you can't even tell I've been bitten unless you know where exactly to look at with a magnifying glass.
About the only thing you really have to worry about from a bite from a harmless snake species is jerking your hand away too quickly in reflex... because the snake's teeth are curved inward, your jerking motion can cause some of the teeth to drag and break off in your skin.. it's like getting a splinter.. just pull them out with tweezers. People who handle snakes frequently learn to suppress that reflex jerk to prevent causing injury to the snake!
Now that's not accounting for when dealing with the huge snakes... those types of bites depending on the location should be seen by a doctor. Not so much because of infections but because there is more surface area they can affect and the larger the snake the larger the teeth so you are no longer dealing with shallow skin surface prickings, but are now dealing with real honest puncture wounds capable of hitting a decent size vein which can cause problems with getting bleeding under control. In the case of large retics or rock pythons whose teeth can reach upwards of an inch or so in length, they can even hit arteries and tendons causing more problems with bleeding and/or mechanical damage/scaring.
Personally, I wouldn't mind getting attacked by a modest size python (under 10 feet)... i'll have some pricks in my skin and maybe a few bruises for a couple days but I'll be fine. I would, however, be horrified to get attacked by an enraged adult green iguana (with comparable teeth size to a modest sized python) ..yanno the kind of lizard that pet stores STILL sell to little kids all the time.... ..those beasties are fully capable of putting an adult human in the ER and can lead to serious reconstructive surgery as they've been known to do such severe damage (up to an including biting your nose and finger tips off or ripping chunks of flesh out of your arm or leg). I HAVE been bitten by a half-grown sized iguana before (a rescue I took in), but thankfully it wasn't an attack type bite - just a little annoyed graze bite. Still, even though he wasn't being serious, he sliced my hand open as if I had taken a large knife and sliced it open myself... I did not opt to get stitches, though I really should have. I still can't see how people still think those cheap to buy lizards are suitable pets for kids.