MRSA Hits the Streets
Abstract & Commentary
By Mary Elina Ferris, MD, Clinical Associate Professor, University of Southern California. Dr. Ferris reports no financial relationship to this field of study.
Synopsis: Methicillin-resistant Staphylococcus aureus (MRSA) in the community was the cause of the majority of skin and soft tissue infections, and was predominantly of one strain different from MRSA of hospital origin.
Source: King MD, et al. Emergence of community-acquired methicillin-resistant Staphylococcus aureus USA 300 clone as the predominant cause of skin and soft-tissue infections. Ann Intern Med. 2006;144:309-317.
All staphylococcus isolates from community-acquired skin and soft tissue infections for 3½ months from Grady Memorial Hospital and its affiliated clinics in Atlanta, Georgia, were analyzed, amounting to 389 specimens. Infection in hospitalized patients was considered community-acquired if it occurred within 72 hours of admission. Seventy two percent of all S. aureus infections were found to be MRSA, and 87% of those fell into one group (USA300) with a susceptibility profile demonstrating resistance only to beta-lactams and erythromycin and not to clindamycin, levofloxacin, trimethoprim-sulfa or vancomycin.
They also analyzed the initial treatment choices made for these patients and found that only 57% of infections were treated appropriately before sensitivity results were known. Among the MRSA patients, only 18% had been hospitalized during the previous year, suggesting that MRSA acquisition was most likely from the community and not the hospital. More black persons and younger persons had MRSA. Traditional risk factors for MRSA such as previous incarceration or day care attendance were not seen in the available records for the MRSA-infected group.
Commentary
This study in urban Atlanta shows that a particular clone of MRSA has become the most common cause of all community-acquired skin and soft tissue infections, which is clearly increasing based on studies in previous years. This clone remains sensitive to tetracyclines and trimethoprim-sulfa, which is not the case with the classic hospital-acquired MRSA. Other studies have confirmed these trends. Unfortunately, a 4-fold increase in clindamycin resistance, with the most common presentation being abscess and cellulitis, has also been confirmed.1
Susceptibility patterns may vary regionally, so this research reminds us of the urgent need to culture community-acquired skin and soft tissue infections whenever possible to guide our treatment decisions. Drainage of abscesses may be the most important intervention,2 but if there is no fluctuant collection of purulent material to be drained and the clinical setting suggests MRSA, a sulfa drug or tetracycline has been recommended as the best choice for initial empiric therapy.3 Otherwise, treatment is guided by disease severity, clinical response, culture results and cost, but we should certainly be highly suspicious of MRSA in groups not previously thought to be at high risk.
References
1. Purcell K, Fergie J. Epidemic of community-acquired methicillin-resistant Staphylococcus aureus infections: a 14-year study at Driscoll Children's Hospital. Arch Pediatr Adolesc Med. 2005;159:980-985.
2. Ellis MW, et al. Treatment approaches for community-acquired methicillin-resistant Staphylococcus aureus infections. Curr Opin Infect Dis. 2005;18:496-501.
3. Elston DM. Optimal antibacterial treatment of uncomplicated skin and skin structure infections: applying a novel treatment algorithm. J Drugs Dermatol. 2005;4(6 Suppl):s15-19.
Methicillin-resistant Staphylococcus aureus (MRSA) in the community was the cause of the majority of skin and soft tissue infections, and was predominantly of one strain different from MRSA of hospital origin.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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