Preexisting Antibodies and Community-Acquired MRSA

One worrisome feature of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections is the high recurrence rate. Most CA-MRSA strains produce Panton-Valentine leukocidin (PVL; JW Infect Dis Dec 16 2009), and investigators have now questioned whether the development of antibodies to this toxin might affect CA-MRSA disease manifestations.

In initial studies, the investigators used low inocula of MRSA strains, enhanced with particulate foreign bodies, to create skin abscesses in mice. Compared with wild-type PVL-positive CA-MRSA strains, isogenic strains lacking PVL tended to replicate more efficiently. This difference was not seen when higher inocula were used to induce infection, suggesting that under low-inoculum con…