Amoxicillin cannot be used by spreading it directly on the wound, first of all infection must mean that the bacteria reach the inside of the cells and not on the surface. In the same way, there is a lot of bacteria on the surface of the skin, especially gram-positive cocci, like Staphylococcus aureus and so on, but there is no infection, and it is only when this Staphylococcus aureus invades the cells under the skin that a septic infection is caused. If the wound is exposed, it is true that there will be some staphylococci on the surface of the wound, but there is no infection at this time, once infection occurs it must be the staphylococci that have gotten inside the cells. Amoxicillin spread on the wound, and can not be absorbed into the cells, it is a water-soluble component, it is difficult to simply through the diffusion to reach the inside of the cell. It must be taken orally into the bloodstream, through the blood circulation to reach the tissues of the wound, and then it can reach the inside of the cell to kill the pathogenic bacteria that enter the inside of the cell for infection, and when it is spread on the wound there is no antimicrobial effect, on the contrary, it will promote the development of drug resistance of the bacteria on the surface of the wound. So from the point of view of the rational application of antibacterial drugs, a major contraindication is to apply antibacterial drugs externally or rinse the wound, which not only can not kill or inhibit the bacteria, but also lead to bacterial resistance, so amoxicillin can not be directly spread on the wound to use.