Cat bites usually aren't all that painful, at least not for very long, but the big problem is the threat of infection. Those teeth can really penetrate, so it's almost like injecting bacteria deep into your flesh. Proper cleaning of any puncture wound can be difficult, and most cats have a type of bacteria in their mouths called Pasteurella. This pesky organism doesn't cause any trouble in the cat's mouth, but once it gets into your flesh, watch out! By the next morning, the area is swollen and red, and if you don't seek treatment with antibiotics, you could be in for real trouble.