Daptomycin Alone and in Combination for Complicated MRSA Bacteremia

Initial treatment with daptomycin (DAP) for bacteremia caused by methicillin-resistant Staphylococcus aureus (MRSA) complicated by septic pulmonary emboli was found to have a success rate comparable to daptomycin-ceftaroline fosamil (DAP-CPT), according to a brief report published in the European Journal of Clinical Microbiology & Infectious Diseases.

The use of DAP in septic pulmonary emboli is controversial. Investigators therefore analyzed 29 patients with MRSA bacteremia complicated by septic pulmonary emboli treated with either DAP (n=14) or DAP-CPT (n=15) in order to evaluate outcomes.

No significant differences were identified in baseline characteristics between treatment groups; the median age of the total study population was 37 years (interquartile ratio, 32-54 years) and most were people who used drugs (79.3%). Composite success was not different between groups (DAP 71.4% vs DAP-CPT 80.0%; P = .68). According to the investigators, 3 of 4 clinical failures in the DAP monotherapy group were driven by the addition of an alternative anti-MRSA agent. They further note that, “importantly, one patient who failed in the DAP monotherapy arm had a DAP MIC of 2 mg/L (non-susceptible per [the Clinical and Laboratory Standards Institute]).” A single patient in the DAP monotherapy group experienced an elevated creatine phosphokinase level, and a single patient in the DAP-CPT group experienced thrombocytopenia attributable to CPT. Both of these adverse effects improved after discontinuation of the antibiotic treatment.

The investigators note that this was “the largest, real-world comparison analyzing initial

monotherapy with DAP versus DAP-CPT in MRSA bacteremia complicated by [septic pulmonary emboli].” However, the analysis is still small in size and only patients with MRSA and concomitant bacteremia were included. The report is also limited by the fact that septic pulmonary emboli are difficult to diagnose with absolute certainty. Inclusion was based on physician interpretation based on clinical presentation and imaging, and follow-up imaging was not available in all cases.

Despite the study limitations, the investigators conclude that DAP monotherapy or DAP-CPT combination therapy appear to be reasonable options, “with regard to effectiveness and tolerability during prolonged treatment courses for MRSA bacteremia complicated by [septic pulmonary emboli].” They add that like other antimicrobials used in all indications, there should be a low threshold to alter therapy in cases that lack clinical improvement.

Reference

Morrisette T, Lagnf AM, Alosaimy S, Rybak MJ. A comparison of daptomycin alone and in combination with ceftaroline fosamil for methicillin-resistant Staphylococcus aureus bacteremia complicated by septic pulmonary emboli [published online June 13, 2020]. Eur J Clin Microbiol Infect Dis. doi:10.1007/s10096-020-03941-5