MRSA: A Deadly Pathogen with Fewer and Fewer Treatment Options

Note: For the most recent data on MRSA, visit the CDC's website.

Staphylococcus aureus, or staph, is a common bacterium that exists in our environment and our bodies. Most of the time it does no harm. Sometimes, however, it can cause infection and require treatment. MRSA refers to strains of S. aureus that are resistant to the antibiotic methicillin and a host of other drugs used to treat infection.

Vital Statistics

• MRSA is responsible for at least 11,000 U.S. deaths and 80,000 invasive infections per year.¹
• Patients with MRSA can be twice as likely to die as patients with staph infections that can be treated with methicillin.²
• Annual costs of treating hospitalized MRSA patients are between $3.2 billion and $4.2 billion in the United States.³

MRSA Is Becoming Resistant to a Growing Number of Antibiotics

MRSA is most commonly resistant to antibiotics used to treat conventional staph infections.⁶

• Beta-lactams (penicillins and cephalosporins)
• Fluoroquinolones (e.g., levofloxacin)
• Macrolides (e.g., erythromycin, azithromycin)

MRSA can usually be treated with “last-resort” antibiotics, but some resistance has been reported to:⁷
• Clindamycin ^{8, 9}
• Vancomycin ¹⁰
• Linezolid and daptomycin^10,11 (the last two novel drugs approved to treat drug-resistant S. aureus infections).

Related Items

• MRSA on the Appalachian Trail: The Story of Steve Weisel
• Jamel Sawyer: A Young Man Fights MRSA
• Antibiotics and Innovation Project

1 R. M. Klevens et al., “Invasive Methicillin-Resistant Staphylococcus Aureus Infections in the United States,” JAMA 298, no. 15 (2007): 1763-71.
2 Centers for Disease Control and Prevention, Antibiotic Resistance Threats in the United States, 2013, September 2013, http://www.cdc.gov/drugresistance/threat-report-2013/pdf/ar-threats-2013-508.pdf.
3 E. Rojas and L. Liu, “Estimating the annual hospital excess cost of methicillin-resistant Staphylococcus aureus infections in the United States,” presented at International Society for Pharmacoeconomics and Outcomes Research (IPSOR) Tenth Annual International Meeting, Washington, DC, May 2005.
4 H. Boucher, L. G. Miller, and R. R. Razonable, “Serious Infections Caused by Methicillin-Resistant Staphylococcus Aureus,” Clin Infect Dis
5 1 Suppl 2(2010): S183-97.5 A. Elixhauser and C. Steiner, “Infections with Methicillin-Resistant Staphylococcus Aureus (MRSA) in U.S. Hospitals, 1993–2005,” HCUP Statistical Brief #35. July 2007. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/reports/statbriefs/sb35.pdf.
6 K. Chua et al., “Antimicrobial Resistance: Not Community-Associated Methicillin-Resistant Staphylococcus Aureus (CA-MRSA)! A Clinician's Guide to Community MRSA — Its Evolving Antimicrobial Resistance and Implications for Therapy,” Clin Infect Dis 52, no. 1 (2011): 99-114.
7 C. Liu et al., “Clinical Practice Guidelines by the Infectious Diseases Society of America for the Treatment of Methicillin-Resistant Staphylococcus Aureus Infections in Adults and Children,“ Clin Infect Dis 52, no. 3 (2011): e18-55.
8 L. L. Han et al., “High Frequencies of Clindamycin and Tetracycline Resistance in Methicillin-Resistant Staphylococcus Aureus Pulsed-Field Type Usa300 Isolates Collected at a Boston Ambulatory Health Center,” J Clin Microbiol 45, no. 4 (2007): 1350-2.
9 R. E. Mendes et al., “Characterization of Baseline Methicillin-Resistant Staphylococcus Aureus Isolates Recovered from Phase Iv Clinical Trial for Linezolid,” J Clin Microbiol 48, no. 2 (2010): 568-74.
10 A. Mangili et al., “Daptomycin-Resistant, Methicillin-Resistant Staphylococcus Aureus Bacteremia,” Clin Infect Dis 40, no. 7 (2005): 1058-60.11 P. Wilson et al., “Linezolid Resistance in Clinical Isolates of Staphylococcus Aureus,” J Antimicrob Chemother 51, no. 1 (2003): 186-8.