Staphylococcus aureus pneumonia: emergence of MRSA in the community.

The clinical presentation of staphylococcal pneumonia is changing. Healthy young people without traditional risk factors for Staphylococcus aureus disease are presenting with severe necrotizing infection and high mortality. The clinical picture is reminiscent of outbreaks of postinfluenzal staphylococcal pneumonia seen in the past century. Most of these staphylococcal strains are methicillin-resistant and are not health care associated. Many strains contain toxins that are likely responsible for the severity of illness seen. Panton-Valentine leukocidin has rarely been identified in S. aureus until recently. It appears that the genetic element for methicillin resistance has been introduced into multiple highly virulent methicillin-susceptible strains with great potential for further spread. Early recognition and treatment of possible community-acquired methicillin-resistant S. aureus (CA-MRSA) is essential. It is equally important to attain microbiological confirmation of the diagnosis for optimal treatment and to initiate appropriate infection control procedures.