Daptomycin is a cyclic lipopeptide antibiotic that has a unique mechanism of action. It binds to the bacterial cell membranes, causing rapid depolarization of the membrane due to K efflux and associated disruption of DNA, RNA, and protein synthesis; the result is rapid concentration-dependent bacterial death (see Effectiveness).
Daptomycin has activity against the following:
Daptomycin is used mainly for infections caused by
However, methicillin-resistant S. aureus and vancomycin-resistant enterococci may become resistant during daptomycin therapy, resulting in relapsing or persistent infection.
Daptomycin is inferior to ceftriaxone for pneumonia, presumably because daptomycin can bind to pulmonary surfactant, reducing daptomycin’s activity in the alveolar epithelial lining fluid.
Adverse effects include
Chronic use may cause reversible organizing pneumonia with eosinophilic pulmonary infiltrates, presumably because daptomycin binds to pulmonary surfactant and thus accumulates in the alveolar spaces.
Skeletal myopathy due to daptomycin is reversible but seldom occurs with once/day dosing.