Staphylococcus Aureus Pneumonia: Emergence of MRSA in the Community

Suzanne F. Bradley, MD


Semin Respir Crit Care Med. 2005;26(6):643-649. 

In This Article

Community-Acquired Methicillin-Resistant Staphylococcus Aureus—an Evolving Definition

Classic Centers for Disease Control and Prevention (CDC) definitions of nosocomially acquired versus community-acquired infections have been based on the presumed site of acquisition of the infection. In general, patients who developed infection within 48 to 72 hours of admission were presumed to have an infection acquired from the community.[1]

Since its initial description in the United States in 1968, methicillin-resistant Staphylococcus aureus (MRSA) infection was almost exclusively associated with acquisition from hospitals, nursing facilities, dialysis units, and other health care settings where skilled care was provided.[2,3] In the 1980s and 1990s, it was recognized that an increasing number of patients were admitted from the community with their MRSA infection. However, these individuals generally had some epidemiological link to health care settings through recent admission, contact through dialysis or infusion centers, or contact with a family member who worked in the health care industry.[4] Many patients were known MRSA carriers, a risk factor for subsequent infection that persists for months to years. Other MRSA infections were associated with the use of intravenous drugs in some communities.[5] Terminology began to change to health care-associated (HA-MRSA) and community-associated or community-onset MRSA to reflect the concept that the place of MRSA infection could no longer be ascertained.[2] Those community-associated strains were closely linked to health care-associated strains on the basis of antimicrobial susceptibilities and molecular typing methods.[3]

In the late 1990s, true community-acquired MRSA (CA-MRSA) was found among clusters of severe and fatal MRSA infections described in healthy children from Minnesota, North Dakota, and Illinois who had no identifiable link to the health care setting.[6,7,8] Subsequently, many reports of CA-MRSA in otherwise healthy persons rapidly emerged from various geographic areas in the United States, Canada, Australia, New Zealand, and others. Necrotizing pneumonia and outbreaks of skin and soft tissue infections (SSTIs) among athletes, native peoples, and prisoners have primarily been reported.[3,8,9]


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