Staphylococcus aureus Infections on the Rise
Methicillin-resistant Staphylococcus aureus USA300 clone identified in majority of cases
THURSDAY, Aug. 30 (HealthDay News) -- The prevalence of skin and soft tissue infections due to community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is rising, researchers report in a study published in the August issue of Emerging Infectious Diseases. Most of these cases are due to the USA300 clone, and researchers postulate that the clone's growing virulence is to blame.
Jennifer K. Johnson, M.D., of the University of Maryland School of Medicine in Baltimore, and colleagues conducted a retrospective analysis of MRSA and skin and soft tissue infections between 2001 and 2005 at a Baltimore Veterans Affairs medical facility. Molecular typing was performed on patient samples to identify the USA300 clone.
The proportion of medical visits for MRSA infections in patients without a history of MRSA colonization or infection increased between 2001-2005 from 0.2 to 5.9 cases per 1,000 patient visits, most of which were skin and soft tissue infections. The proportion of MRSA infections due to the USA300 clone increased from 0 percent in 2001 to 84 percent in 2005.
"The emergence of the USA300 clones has led to not only an increase in CA-MRSA infections but also an overall increase in skin and soft tissue infections in our patient population," the authors write. "This finding suggests that this clone is becoming more virulent with a greater propensity to cause skin and soft tissue infections."