Emergence of daptomycin non-susceptible coagulase-negative staphylococci in patients with cardiovascular device infections Two cases report investigated by whole genome analysis

Rationale: Daptomycin (DAP) is a key drug for treating severe Staphylococcus infections. The emergence of DAP non-susceptible Staphylococcus aureus has been widely recognized in clinical situations, although the clinical status of DAP non-susceptible coagulase-negative Staphylococcus (CoNS) infections is unclear. We encountered 2 cases of cardiovascular device infections that were associated with DAP non-susceptible CoNS. Patient concerns: The first case involved a 60-year-old woman with a pump pocket infection in a left ventricular assist device. DAP non-susceptible Staphylococcus capitis subsp. ureolyticus was isolated from a blood culture after treatment using vancomycin (10 days) and DAP (6 days). The second case involved a 71-year-old man with an aortic graft infection. DAP non-susceptible S capitis subsp. ureolyticus was detected in pus after treatment using vancomycin (2 weeks) and DAP (1 week) without complete removal and debridement. Diagnosis: Cardiovascular device infections caused by DAP non-susceptible CoNS. Interventions and outcomes: Whole genome sequencing of these strains revealed multiple mutations in genes that are related to DAP-non-susceptibility in S aureus, which created amino acid substitutions in mprF, dltAB, dltD, rpoC, yycG, cls2, pgsA, and vraSR. To the very best of our knowledge, the substitution patterns were not identical to those previously reported in DAP non-susceptibile S aureus. Lessons: Clinicians should be cautious regarding the emergence of DAP non-susceptible CoNS, especially in cases with implanted prosthetic devices, inadequate debridement, and prior usage of vancomycin and DAP. Further studies are needed to understand the relevance of these genetic changes and DAP-non-susceptibility in CoNS strains.