Community-Associated Methicillin-ResistantStaphylococcus aureus

Abstract

In the past decade, the view of methicillin-resistant Staphylococcus aureus (MRSA) epidemiology has changed. A large burden of community associated MRSA (CA-MRSA) disease was reported by prison and jail systems in California, Texas, Mississippi, and Georgia. Outbreaks have provided incentives to examine the epidemiology of CA-MRSA in closer detail. Importantly, these increases were directly translated into similar increases in the overall burden of S. aureus disease. Important genetic phenomena are believed to be responsible for the phenotypic differences observed in comparisons of CA-MRSA and hospital-associated MRSA (HA-MRSA) isolates. A survey of 16 toxin genes known to be present in genomically sequenced S. aureus strains revealed that important differences can be identified when HA-MRSA and CA-MRSA isolates are compared. Six exotoxin genes were found significantly more often among CA-MRSA isolates, and seven were found significantly more often among HA-MRSA strains. Asymptomatic colonization is the most frequent outcome of host interaction with S. aureus. The mainstay of treatment for skin abscesses is incision and drainage of the lesion. The pneumonia may be classified as ‘’necrotizing’’ if the chest CT shows a consolidative infiltrate, destruction of normal lung architecture, and loss of tissue enhancement. The CA-MRSA epidemic has complicated the selection of empirical antibiotic therapy for presumed S. aureus infections. Distinguishing HA-MRSA from CA-MRSA is useful in defining the changing epidemiology, identifying those at risk, and choosing empirical antibiotic therapy when required.