Staphylococcus aureus or staph is a common bacteria present in approximately 25 percent of the population. Staph is frequently found in the nose and on the skin. Staph infections range in severity from a simple skin infection to pneumonia or bloodstream infections. Sometimes the bacteria becomes resistant to antibiotics. Methicillin-resistant staphylococcus aureas, or MRSA, is resistant to several antibiotics used to treat ordinary staph infections. However, effective treatments are still available.
Oral Antibiotics
According to 2006 Center for Disease Control (CDC) published treatment guidelines, several oral antibiotics are effective against MRSA infections in the community.
Clindamycin is used for skin and skin structure infections (SSSI) caused by MRSA. The drug is dosed multiple times per day and may cause significant stomach upset and diarrhea.
Tetracyclline drugs, including doxycycline or minocycline, are also used, primarily for non-invasive SSSI caused by MRSA. Evidence does not support use of tetracyclines for invasive MRSA infections. The class of drugs should be avoided by pregnant woman and children under 8, due to the risk of tooth enamel abnormalities or discoloration and decreased bone growth.
Trimethoprim/sulfamethoxazole (TMP/SMX) is frequently used for non-invasive MRSA infections. The drug should not be used by pregnant women, or children under 2 months of age.
Rifampin may be used in combination with other antibiotics for enhanced eradication of MRSA. The drug should never be used alone, as resistance may quickly develop. Drug interactions are a significant concern with rifampin therapy.
Linezolid (Zyvox) is a newer agent which has Food and Drug Administration (FDA) approval for treatment of MRSA infections. The drug is highly effective, but more costly than other agents. The CDC recommends reserving linezolid use for serious infections to prevent possible development of resistance.
Resistance to fluoroquinolones, such as ciprofloxacin and levofloxacin (Levaquin), and macrolides, including erythomycin, azithromycin and clarithromycin, is common, making both classes of antibiotics of little use in treating MRSA.
Intravenous Antibiotics
Intravenous (IV) antibiotics are used for serious MRSA infections, especially those requiring hospitalization, according to CDC guidelines.
Vancomycin is the first-line agent for treatment of severe MRSA infections. Other agents, such as clindamycin, TMP/SMX, linezolid (Zyvox), daptomycin (Cubicin), quinupristin-dalfopristin (Synercid) or tygecycline (Tygacil) may be appropriate in some situations.
Consultation with an infectious disease specialist is recommended for serious MRSA infections.
Getting the Right Treament
MRSA infection is a serious health concern, but it can be treated. Effective oral and IV treatment options for MRSA are available, despite resistance to many common antibiotics. In many cases, susceptability testing is appropriate to confirm the correct choice on antibiotic therapy.
