The organism causing destruction of skin grafts is –
**Core Concept**
The destruction of skin grafts can occur due to an immune response against the graft, which is a common complication in transplant patients. This is mediated by the body's immune cells, such as T lymphocytes, that recognize the graft as foreign. The rejection of a skin graft is an example of an allograft rejection, where the immune system mounts a response against the graft.
**Why the Correct Answer is Right**
The destruction of skin grafts is primarily caused by the action of cytotoxic T lymphocytes (CTLs), which recognize and bind to major histocompatibility complex (MHC) molecules on the surface of the graft cells. This recognition leads to the activation of CTLs, which then release cytotoxins that kill the graft cells. The presence of antibodies against the graft can also contribute to rejection, but this is less common. In addition, the graft-versus-host disease (GVHD) can occur when the graft cells recognize the host's tissues as foreign and mount an immune response against them.
**Why Each Wrong Option is Incorrect**
**Option A:** Staphylococcus aureus is a common cause of skin infections, but it is not typically associated with the destruction of skin grafts.
**Option B:** Pseudomonas aeruginosa is an opportunistic pathogen that can cause infections in immunocompromised patients, but it is not the primary cause of skin graft rejection.
**Option C:** Candida species can cause fungal infections in immunocompromised patients, but they are not typically associated with the destruction of skin grafts.
**Clinical Pearl / High-Yield Fact**
Skin graft rejection can be prevented by using immunosuppressive drugs, such as corticosteroids, calcineurin inhibitors, and monoclonal antibodies, which suppress the immune response against the graft.
**Correct Answer:** B. Pseudomonas aeruginosa