Panton-Valentine leukocidin

PVL is a bicomponent toxin whose two subunits assemble into pores in leukocyte membranes, causing lysis and release of inflammatory mediators. It is carried by a bacteriophage and is found in a large majority of community-acquired MRSA strains, notably the USA300 clone, but rarely in hospital-acquired MRSA. Clinically it is linked to recurrent furunculosis and abscesses in otherwise healthy people, often clustering in households, athletic teams, prisons, and military recruits, where transmission is by skin contact and shared equipment. Its most feared manifestation is necrotizing haemorrhagic pneumonia, characteristically following an influenza-like illness in a previously well adolescent or young adult, with rapid cavitation, leukopenia, haemoptysis, and high mortality. Management of PVL-associated disease combines drainage with agents that suppress toxin production — clindamycin or linezolid — alongside vancomycin, plus decolonization of the patient and household with nasal mupirocin and chlorhexidine washes. PVL should not be confused with the toxic shock syndrome toxin, which is a superantigen.