Research by a team of scientists from France and the United States is shedding light on why strains of toxin-secreting Staphylococcus aureus that are associated with the current outbreak of community-associated methicillin-resistant Staphylococcus aureus (MRSA) sometimes cause a deadly necrotizing pneumonia (Labandeira-Rey M. Science. doi:10.1126/science.113765 [published online January 18, 2007]).
Previous studies in cell cultures revealed that the toxin, called Panton Valentine leukocidin (PVL), targets and forms pore in the membranes of cells of the immune system, causing them to lyse. In the new work, in mice, the researchers found that PVL itself is sufficient to cause pneumonia, and that it also spurs the bacterium to overproduce other factors that enhance inflammation and the attachment of the pathogen to lung tissue.
Stephenson J. MRSA and Pneumonia. JAMA. 2007;297(7):686. doi:10.1001/jama.297.7.686-d