A Multi-center Prospective Randomized Open Label Study of Utilizing Interleukin 10 (IL-10) Levels as a Guide for Antibiotic Selection for Methicillin Resistant Staphylococcus Aureus Bacteremia

Patients with MRSaB have primary therapeutic failure rates of 40-50% and high mortality rate of 10-50% when treated with the recommended standard antimicrobial therapy. (Sharp) local data for MRSaB for 2014 shows an all-cause mortality rate of 29%. Recent studies have been published that utilize the predictive biomarker, IL-10, aiding the understanding for the wide variability in mortality. Further studies are needed to elucidate the clinical relevance of utilizing IL-10 levels to optimize MRSaB management and whether or not patient outcomes are enhanced.

Under current standard treatment strategies, vancomycin 15 mg/kg IVPB every 12 hrs following a 30 mg/kg IVPB loading dose is the first line of antibiotic therapy initiated with known or suspected MRSaB. Only when patients have showed an unsatisfactory clinical response such as prolonged bacteremia and/or continued clinical signs of uncontrolled infection are more potent/aggressive and more expensive antibiotic choices considered in most cases. Even the time for consideration of such a switch is a matter of controversy, with current MRSA treatment guidelines recommending a switch after 7-days of failure.

Several recent studies have shown that an elevated IL-10 level is an independent risk factor of mortality. In animal models, it has been shown that the bacterial cell wall of Staphylococcus aureus stimulates the production of IL-10. A small study by Rose et al. showed that this observation is consistent in humans. In another study, the authors concluded that elevated IL-10 at the time of presentation is a predictive value of mortality in patients with MRSaB4. In addition, the authors concluded that IL-10 may serve as a biomarker for very early risk stratification, with selection of standard therapy for low-risk patients and more potent, expensive, and cumbersome antibiotic therapies reserved for the high-risk patients. Furthermore, it is postulated that treating high risk patients with aggressive/intensified therapy earlier may improve economic and microbiological outcomes, such as a decreased length of treatment, decreased time in the Intensive Care Unit, decreased length of stay in the hospital, and decreased duration of bacteremia.

The aim in this study is to compare the outcomes for patients with elevated IL-10 levels (≥ 8 pg/mL) when treated with standard antibiotic therapy versus early aggressive therapy for the treatment of MRSaB. Aggressive therapy is defined in study to be daptomycin (6-8mg/kg/day) with ceftaroline (600 mg q8hr).