Antimicrobial resistance: it's not just for hospitals.

摘要

Methicillin-reststant staphylococcus aureus (MRSA) is a well-known hospital pathogen. More than 10% of bloodstream infections in hospitals are due to MRSA, and patients with MRSA have worse outcomes than those with methicillin-sensitive S aureus. In recent years, identification of MRSA in otherwise healthy individuals in the community (community-associated MRSA) has become increasingly common. Health care-associated and community-associated MRSA have different clinical and molecular epidemiology. Health care-associated MRSA is associated with invasive disease, health care exposure, and multidrug resistance. Community-associated MRSA has been primarily reported in young, healthy individuals with no recent health care exposure. The strains have generally been sensitive to non-fi-lactam antibiotics, although most have had genes for the Panton-Valentine leukocidin and other enterotoxins that may make these strains more virulent. Health care-associated MRSA is typified by a USA100 pulse-field electrophoretic pattern, while USA300 is the most commonly reported community-associated MRSA pattern in the United States. Complicating the issue is that patients can unknowingly be colonized with MRSA and therefore have onset of disease away from the source of exposure (hence the terms "community onset" or "health care onset"). Furthermore, molecular studies reveal that either strain can appear in both locations.