It can happen via any entry wound. I had it from a mossy bite. My other half gets it regularly and ends up on intravenous anti biotics in hospital as he is just prone to it. His first bout was from a stone in the road flicking up, when he was on his bike.
Mine started on a Friday, & I trusted the antibiotics would work, so I only had paracetamol. I was counting down the hours to Monday morning. I should have gone to A&E for something stronger, but I wasn't thinking straight.
A tooth abcess. I had antibiotics for two days which didn't touch it. My whole face was swollen like a hamster. The pain went right up into my jawbone, cheekbone, nose and eye.
In the end, I lost the tooth, had a root canal filling and a crown.