In a recently published article, Hidayat et al1 observed a high prevalence of clinical methicillin-resistant Staphylococcus aureus (MRSA) strains with an elevated vancomycin minimum inhibitory concentration (2 μg/mL) in a prospective cohort, and they studied treatment outcomes with high-dose vancomycin hydrochloride. The authors concluded that (1) these strains require aggressive empirical vancomycin dosing to achieve trough plasma concentrations greater than 15 μg/mL and (2) combination or alternative therapy should be considered for invasive infections caused by these strains.1 Although they provide convincing data supporting the first part of this conclusion, the reader may feel disappointed with the data supporting the second part (ie, the place of combination or alternative therapy). Indeed, of the 95 patients included in this study, only 15 received vancomycin in combination with linezolid, daptomycin, and/or rifampin, and the only information we have about them from this article is that “the end-of-treatment response appeared more favorable when compared with vancomycin alone.”1(p2143) About the subsets of patients in whom vancomycin was switched to another therapy in this study, the authors provided more data: in the “Comment” section, we learn that 12 (80%) of the 15 patients responded to nonvancomycin therapy, but the list of alternative agents received by these 15 patients is limited to daptomycin (n = 6), linezolid (n = 3), and rifampin (n = 6), which would suggest that 6 of them received rifampin as a monotherapy. However, since it is well acknowledged that the use of rifampin as a single agent for the treatment of S aureus infections is limited by a high rate of development of resistance during therapy, as early as within the first 24 to 48 hours of exposure,2 these patients probably received rifampin in combination with other antistaphylococcal agents in this study, even if this is not stipulated in the article.
Tattevin P, Arvieux C, Michelet C. Alternative Agents for the Treatment of Invasive Infections Due to Methicillin-Resistant Staphylococcus aureus Strains With Reduced Susceptibility to Vancomycin. Arch Intern Med. 2007;167(11):1206. doi:10.1001/archinte.167.11.1206-a