Nafcillin Augmentation of Daptomycin and Cathelicidin LL-37 Killing of Methicillin-resistant Staphylococcus epidermidis: Foundations of Successful Therapy of Endocarditis.

Methicillin-resistant Staphylococcus epidermidis (MRSE) endocarditis failing conventional therapy has been successfully treated with nafcillin plus daptomycin in the clinic. In vitro studies showed that nafcillin enhanced daptomycin killing of MRSE in both planktonic cells and biofilm. Nafcillin exposure also sensitized MRSE to killing by human neutrophils and cathelicidin antimicrobial peptide LL-37. Fluorescent microscopy showed increased daptomycin and LL-37 binding to the MRSE bacterial surface upon nafcillin treatment. Ceftaroline also increased MRSE killing by daptomycin in planktonic cultures and biofilms, as well as daptomycin and LL-37 binding on the bacterial surface. Nafcillin, ceftaroline, and possibly other ß-lactams, may serve an important role in the therapy of MRSE endocarditis through augmentation of cationic peptide, the innate immune system, and daptomycin killing. Clinical studies will be needed to determine how early these regimens should be deployed to optimize clinical outcome.

Examining the use of ceftaroline in the treatment of Streptococcus pneumoniae meningitis with reference to human cathelicidin LL-37.

Five cases of bacterial meningitis treated with ceftaroline (4 Streptococcus pneumoniae and 1 Staphylococcus aureus) are summarized here. The pharmacodynamics of human cathelicidin LL-37 and ceftaroline were evaluated against S. pneumoniae. Patients who received ceftaroline 600 mg every 8 h (q8h) (1 S. aureus and 3 S. pneumoniae) were successfully treated; treatment failed in 1 patient with S. pneumoniae who received 600 mg q12h. Ceftaroline increased the negative surface charge and sensitized S. pneumoniae to killing by LL-37, a peptide implicated in blood-brain barrier defense.

Treatment of high-level gentamicin-resistant Enterococcus faecalis endocarditis with daptomycin plus ceftaroline.

A recurrent case of left-sided endocarditis caused by high-level aminoglycoside-resistant Enterococcus faecalis was successfully treated with ceftaroline and daptomycin. This combination demonstrated excellent synergy in vitro. Mechanistically, ceftaroline enhanced binding of daptomycin to the cell membrane and sensitized E. faecalis to killing by human cathelicidin LL-37, a cationic innate host defense peptide. Daptomycin plus ceftaroline may be considered in salvage therapy in E. faecalis endovascular infections and requires further study.