Treatment for MRSA Complicated Bacteremia and Infective Endocarditis

Findings published in Clinical Microbiology and Infection provide a proof of concept for the treatment of complicated bacteremia and infective endocarditis with fosfomycin plus imipenem (FOS+IMI) compared with vancomycin alone.¹

Methicillin-resistant Staphylococcus aureus (MRSA), a common cause of complicated bacteremia and infective endocarditis, currently has few treatment options and often poor prognosis. Previous work has demonstrated that FOS+IMI is an effective salvage treatment for MRSA complicated bacteremia and infective endocarditis.²

This open-label randomized clinical trial (ClinicalTrials.gov identifier: NCT00871104) was undertaken in 10 tertiary care Spanish hospitals between 2009 to 2014 to investigate the efficacy and safety of FOS+IMI compared with vancomycin for treatment of patients with MRSA complicated bacteremia and infective endocarditis. However, enrollment was flawed and final sample size too low for robust analysis or firm conclusion.

The final sample consisted of 7 patients with complicated bacteremia and 8 patients with infective endocarditis. Eight patients were randomly assigned to FOS+IMI and 7 to vancomycin. Cure rates were 50% and 43% for FOS+IMI and vancomycin, respectively. The 4 patients who failed to respond to FOS+IMI died; however, none had positive blood culture at time of death, and they did not die from drug-related complications. One patient receiving FOS+IMI had a salt overload, and treatment was discontinued, but no patients presented severe complications from ionic imbalances, seizures secondary to imipenem, or superinfections resulting from multiresistant microorganisms.

According to investigators, these results indicate that FOS+IMI is a safe option and provides a proof of concept that FOS+IMI is a potential alternative to vancomycin. Further research is needed to fully evaluate the safety and efficacy of this treatment course and researchers hope this study will “boost research on this area.”

Reference

1. Pericàs JM, Moreno A, Almela M, et al. Efficacy and safety of fosfomycin plus imipenem vs. vancomycin for complicated bacteremia and endocarditis due to methicillin-resistant Staphylococcus aureus: a randomized clinical trial [published online February 2, 2018]. Clin Microbiol Infect. doi: 10.1016/j.cmi.2018.01.010 
2. del Río A, Gasch O, Moreno A, et al; FOSIMI Investigators. Efficacy and safety of fosfomycin plus imipenem as rescue therapy for complicated bacteremia and endocarditis due to methicillin-resistant Staphylococcus aureus: a multicenter clinical trial. Clin Infect Dis. 2014;59:1105-1112.