Community MRSA and Panton-Valentine leukocidin (PVL): the perfect storm, or a storm in a tea-cup?

Abstract

Staphylococcus aureus is well known for its propensity to encode and express a formidable range of virulence determinants that can cause considerable morbidity and mortality in its host. Amongst these determinants is Panton-Valentine leukocidin (PVL), a cytolytic exotoxin first described in the late 19th century. This toxin is found in many S. aureus clones; however, of particular concern is the fact that community-acquired methicillin-resistant S. aureus (CA-MRSA) clones that contain the PVL determinant have been associated with severe necrotising cutaneous and pulmonary infections in previously well individuals. These reports raise the spectre of a true ‘superbug’ – one that is readily transmissible, resistant to front-line antimicrobial agents, and potentially more virulent that other S. aureus strains. Specific therapeutic approaches directed towards the expression and/or activity of PVL, or the elimination of carriage and transmission of S. aureus that contains PVL determinants, are being considered; however, the effectiveness of such approaches has yet to be determined.