Extremely low excretion of daptomycin into breast milk of a nursing mother with methicillin-resistant Staphylococcus aureus pelvic inflammatory disease.

Antibiotic treatment for pelvic inflammatory disease (PID) is often broad spectrum and targets a diverse range of vaginal flora. Treatment of PID in nursing mothers presents a particular clinical challenge because use of antimicrobials during breastfeeding poses several potential risks to infants. Excretion of drugs into breast milk can occur through different mechanisms and depends on the characteristics of both the drug and the mother. Whether daptomycin is excreted into breast milk is unknown, as is its subsequent exposure to breastfeeding infants and the associated risks. We describe a case of PID caused by methicillin-resistant Staphylococcus aureus, an uncommon pathogen in PID, in a breastfeeding mother who was successfully treated with daptomycin. Daptomycin concentrations in her breast milk were measured to determine potential exposure to her infant. These concentrations were extremely low, with an estimated milk:plasma ratio of 0.0012. Although additional confirmatory studies are needed, daptomycin may be a reasonable option in the treatment of PID caused by gram-positive organisms that are resistant to other antibiotics.