The Great Debate: Combination or Monotherapy for Prolonged MRSA Bacteremia?

Determining treatment regimens for prolonged methicillin-resistant Staphylococcus aureus (MRSA) bacteremia has long confounded clinicians who debate whether combination or monotherapy is most effective.

Investigators with the University of Kentucky presented data at ASM Microbe 2019 comparing the outcomes of ceftaroline plus vancomycin or daptomycin combination therapy versus monotherapy in adults with complicated and prolonged MRSA bacteremia initially treated with supplemental ceftaroline.

The study retrospectively reviewed cases of MRSA bacteremia in 34 adult patients who were hospitalized at University of Kentucky Medical Center between January 2015 and December 2017. Comorbidities included native valve infective endocarditis, osteomyelitis, brain abscess, and endovascular infection, and all participants had at least 4 days of documented bacteremia while on vancomycin or daptomycin, with ceftaroline consequently added.

The study population was split into 2 groups, each receiving 4-6 weeks of therapy: 1 combination group of 18 subjects, who continued on ceftaroline plus vancomycin or daptomycin following bacteremia resolution; and 1 monotherapy subset of 16 subjects, who were de-escalated to vancomycin or daptomycin alone. The research team quantified patients’ acute severity of illness via the Pitt bacteremia scoring (PBS) model, and listed bacteremia recurrence, inpatient mortality, 30-day readmission, acute kidney injury (AKI), and leukopenia as primary outcomes.

The prominent infection in the monotherapy group was native valve infective endocarditis, present in 88% of patients (14 out of 16), while the most common infection in the combination subset was osteomyelitis (affecting 44%, 8 out of 18 patients). Median PBS value was 2 in the combination group and 1 in the monotherapy group. No statistically significant difference was seen comparatively among the subgroups in terms of previously denoted treatment outcomes.

“In subjects with complicated and prolonged MRSA bacteremia requiring the addition of ceftaroline to vancomycin or daptomycin, de-escalation to monotherapy upon bacteremia resolution did not result in unfavorable outcome differences compared to those who continued combination therapy,” investigators concluded.

The poster, “Comparing the Outcomes of Ceftaroline Plus Vancomycin or Daptomycin Combination Therapy versus Monotherapy in Adults with Complicated and Prolonged Methicillin-Resistant Staphylococcus aureus Bacteremia Initially Treated with Supplemental Ceftaroline,” was presented Friday, June 21, 2019, at ASM Microbe 2019 in San Francisco, California.