Pharmacoeconomic advantages of oral minocycline for the therapy of methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTIs).

Dear Editor, I read with great interest the article by Dr. Seaton et al. regarding the economic aspects of methicillin-resistant Staphylococcus aureus (MRSA) therapy for complicated skin and soft tissue infections (SSTIs) [1]. Their interesting and well executed paper merits additional comments and a North American perspective. The authors’ article onMRSA SSTIs discussed the costs of intravenous (IV) antibiotic regimens and the cost savings of early in-house discharge using IV to oral (PO) switch therapy and outpatient parenteral antibiotic therapy (OPAT) using linezolid, rifampicin, or doxycycline [2–7]. MRSA SSTIs mainly present as cutaneous abscesses, in contrast to group A SSTIs, that present as cellulitis [8, 9]. The cornerstone of therapy for MRSA SSTI cutaneous abscesses is incision and drainage. Antimicrobial therapy is adjunctive to prevent bacteremia and further extension of theMRSASSTI [8]. The cost of IV antibiotics is usually substantially higher than the equivalent PO dose [1–3]. On the basis of drug acquisition costs alone, it is obvious that IV to PO switch therapy is much less expensive than IV therapy to the healthcare system [6, 7, 10]. Not only are antibiotic costs less in IV to PO switch programs, but the patients’ length of stay (LOS) is also decreased with earlier discharge on PO therapy [11]. Non-critically ill patients with serious systemic infections may also be effectively managed with oral antibiotic therapy alone [12–15]. Physicians lacking IV to PO switch experience are often reluctant to treat hospitalized patients using PO antibiotics alone [11, 12]. If the PO antibiotic selected has similar pharmacokinetics, i.e., serum half life (t1/2), blood and tissue levels, etc., as its IV equivalent, there are few reasons to use IV therapy instead of PO therapy. Certainly, critically ill patients may benefit from initial IV therapy until clinical improvement [11, 12]. However, most patients, even those who are critically ill, have been effectively treated by the oral route [13–15]. Clearly, those patients who are unable to absorb oral antibiotics necessarily must be treated IV [16, 17]. While OPAT is less costly than inpatient IV therapy, IV to PO switch therapy or oral therapy alone are more economical ways to treat patients without sacrificing clinical efficacy [5, 7]. While some antibiotics are not available in the United States and/or reflect differences in antimicrobial prescribing on both sides of the Atlantic, there are important cost implications in how antibiotic therapy is administered [17] (Table 1). Whether MRSA SSTIs are treated with monotherapy or multiple drugs, economically, it matters whether antibiotics are administered IVor orally [13, 10, 18]. In the hospital setting, many patients with SSTIs and most patients with SSTIs in the outpatient setting may be treated effectively entirely via the oral route [5, 12]. Over the past several decades, I have used minocycline extensively for the treatment of MRSA infections. Minocycline has several advantages and a good safety profile, and is effective against hospital-acquired MRSA (HA-MRSA), community-onset MRSA (CO-MRSA), and community-acquired MRSA (CAMRSA) strains [16, 17]. Other oral MRSA antibiotics, e.g., clindamycin, trimethoprim–sulfamethoxazole (TMP-SMX), or doxycycline, are only variably clinically effective against CA-MRSA and lack efficacy against HA-MRSA and COMRSA, even if they are reported to be susceptible to MRSA in vitro [19–22]. Doxycycline, in particular, is often unable to eradicate CA-MRSA [22], perhaps because doxycycline induces its own resistance with MRSA [19]. MRSA SSTIs B. A. Cunha (*) Infectious Disease Division, Winthrop-University Hospital, 222 Station Plaza North (Suite #432), Mineola, NY 11501, USA e-mail: bacunha@winthrop.org