Rifampicin inhibts the DNA dependent RNA polymerase and is rapidly bactericidal against Staphylococcus aureus with extremely low minimum inhibitory concentrations. Its use as monotherapy has been abandoned because of the rapid development of resistance.
ICAAC 2014: S. Harbarth et al: Randomized Non-Inferiority Trial to Compare Trimethoprim-Sulfamethoxazole (TMP-SMX) plus Rifampicin versus Linezolid in the Treatment of Methicillin-Resistant Staphylococcus aureus (MRSA) Infection
This Systematic Review of the literature focuses on the adjunctive use of rifampicin for the treatment of Staphylococcus aureus including MRSA:
Adjunctive Use of Rifampin for the Treatment of Staphylococcus aureus Infections. A Systematic Review of the Literature. Arch Intern Med. 2008;168(8):805-819.
(NHS Review, Centre for Reviews and Dissemination)
In summary, we found that investigations of rifampin adjunctive therapy for S aureus infection are plagued by numerous limitations. There are situations in which adjunctive rifampin therapy seems promising, but none in which benefit is definitively established. We also found that in vitro models seem to contribute little to our understanding of the role of rifampin in vivo given that results are heavily method dependent. Adequately powered clinical studies need to be performed to assess outcomes with or without rifampin in the clinical scenarios in which poor outcomes are common. These include osteomyelitis, hardware-associated infections, and perhaps infections caused by MRSA strains. Given the rising global incidence of MRSA infections, there is an urgent need to better define the role of rifampin for the treatment of clinical S aureus infections.
Forrest GN, Tamura K. Rifampin Combination Therapy for Nonmycobacterial Infections.Clin Microbiol Rev. 2010 Jan;23(1):14-34.
The data supporting rifampin combination therapy in nonmycobacterial infections are limited by a lack of significantly controlled clinical studies. Therefore, its current use is based upon in vitro or in vivo data or retrospective case series, all with major limitations.