HelixTalk Episode #115 - What Every Pharmacist Should Know to Conquer Staph Aureus Infections

Date posted: June 30, 2020, 6:00 am

In this episode, we discuss the historical significance of Staphylococcus aureus including its patterns of antimicrobial resistance and recommended treatments.

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Key Concepts

1. Nearly all Staphylococcus produce B-lactamase, an enzyme that degrades penicillin, amoxicillin, and ampicillin.  These drugs are almost never appropriate for Staphylococcus aureus infections.
2. Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to nearly all B-lactam antibiotics (penicillins, cephalosporins, carbapenems, etc.) because a single gene mutation makes it very difficult for B-lactam antibiotics to bind to its penicillin binding protein.
3. Vancomycin is the drug of choice for severe infections caused by MRSA.  Daptomycin and linezolid are possible alternative options in certain patients.
4. MRSA SSTI infections are usually purulent in nature (associated with abscesses and pus/drainage).  For patients with mild-moderate SSTIs, doxycycline or Bactrim (SMP/TMP) are the preferred options; however, incision and drainage is curative in the vast majority of cases.

References

• Deurenberg RH, Stobberingh EE. The evolution of Staphylococcus aureus. Infect Genet Evol. 2008;8(6):747‐763. doi:10.1016/j.meegid.2008.07.007
• Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America [published correction appears in Clin Infect Dis. 2015 May 1;60(9):1448. Dosage error in article text]. Clin Infect Dis. 2014;59(2):e10‐e52. doi:10.1093/cid/ciu444.