At this point I understand that the human mouth contains tons of virulent bacteria that can infect an open wound. Questions is, if I get a bad cut and spit on my own hand and rub it in, can I get infected? Are the chances any less, or more?
I’m sure QtM will give a more authoritative answer but it’s my understanding that bacteria in tooth plaque poses the greatest risk of infection. That isn’t to say saliva is exactly sterile but it is being constantly replenished.
IANAD, but my guess would be that the presence of some bacteria in your saliva would indicate that you’re already infected. Rubbing 'em into your own wound wouldn’t be necessary at that point. Also, rubbing spit on a cut would just infect the surface of the wound and the outflow of blood would tend to keep surface bacteria out of the wound itself.
Unless you were spitting with a mouthful of carrion or something…
Animals tend to lick their wounds, which I presume aids in keeping all sorts of awful things out. I would use this as evidence that it’s not as bad as getting a tooth (I know a guy who once punched a dude in the mouth and the guy ended up in the hospital for a couple weeks with blood poisoning), but I’m also assuming that animals don’t have antibacterial spit or anything vastly different than what’s in a human mouth.
That probably wasn’t very helpful.
I dunno about saliva, per se, but when I was in Jr. High a couple classmates got into a fight. One punched the other in the mouth breaking a couple teeth and cutting his knuckles. Treatment was delayed for reasons I don’t remember and the wound got infected. His arm was black and swollen about halfway to the elbow by the time they got it under control. Human bites are nasty.
DD
Human bites are the freakin’ nastiest bit wounds around, outside of komodo dragons, anyway. Lots of anaerobic bacteria that live under the gums, and boy do they pack a wallop! Between 10 and 15% of all human bites get infected.
But for reasons not completely understood, self-inflicted bites are less likely to turn into infection. Not that they don’t get infected, but it’s less likely. Theories about as to how the host recognizes resident bacteria from the host and minimizes risk. But if it were not so, every rectal fissure (and everyone gets them) would run a high risk for turning into a massive peri-anal infection.
Also the mechanism of injury is different in a self-bite. Commonly in a human bite injury delivered by another person, it’s either from teeth meeting fist, which tears open the knuckles, tendon sheaths, and joint sheaths, providing direct access to areas which infection loves to live in. Or it’s an occlusive bite, with a very sharp grinding of the flesh between the upper and lower teeth. Self-bites tend to not be so forceful or to the knuckles, pain being the limiting factor.
Saliva itself doesn’t run the same risk of causing an infection. The reason is uncertain, but probably has to do with a lower concentration of pathogenic bacteria, along with possibly other chemical factors in the saliva.
Some nice data here at emedicine: http://www.emedicine.com/med/byname/human-bite-infections.htm