The idiot doctor probed Garfield’s bullet wound with his fingers that weren’t sterilized. He did it multiple times.
Among the doctor’s many horrendous mistakes in his treatment. When Bell convinced him to let him try to use his metal detector to find the bullet, the doctor would only let him look on the side where he claimed the bullet had to be - he wouldn’t let him try to find it on the other side of his body where it was, behind his liver. Then he declared that Bell’s metal detector was useless.