Panton-Valentine Leukocidin is the toxic waste left behind by Staphylococcus aureus bacteria in some cases. This is often the cytotoxin that leads to TSS (Toxic Shock Syndrome) as well as necrotizing fasiitis. PVL is most often found in CA-MRSA, but has been found in MSSA (Methicillin Susceptable Staph aureus) on occasion.
This journal article describes the case of two Jerusalem families that had recurrent infections, and were the first confirmed cases of PVL producing Staph infections in Israel. This article is not terribly difficult for the lay person to understand, and may provide some interesting information on MRSA, MSSA and PVL to those who are looking for it.