Daptomycin resistance of Corynebacterium jeikeium due to pgsA gene mutation acquired during daptomycin treatment in a patient with infective endocarditis.

Daptomycin is an alternative agent for invasive infections caused by Corynebacterium species in patients with intolerance to vancomycin. Although it has recently been recognized that treatment failure with daptomycin due to the emergence of resistant strains during treatment is not uncommon in Corynebacterium striatum infections, it has been unclear whether there is a similar risk in Corynebacterium jeikeium infections. In the presenting case, daptomycin treatment for C. jeikeium endocarditis in a liver transplant recipient with neutropenia failed due to the rapid emergence of the resistant strain. Whole-genome sequencing analysis of blood culture isolates confirmed that a mutation in the pgsA gene, which is also involved in the development of daptomycin resistance in C. striatum, emerged after daptomycin exposure. This case demonstrated that there is a risk of treatment failure due to the emergence of daptomycin-resistant strains even in C. jeikeium infections caused by daptomycin-susceptible strains, particularly in immunocompromised patients and in biofilm infections with high bacterial burden.