Cutibacterium (formerly Propionibacterium) acnes clavicular infection

Cutibacterium (formerly Propionibacterium) acnes(13, 16) is a slow growing, gram-positive bacteria that is naturally found in higher concentrations as skin flora on the chest and back, as well as in other areas with greater numbers of hair follicles.(25, 37) Most of the reported cases of C. acnes shoulder girdle infection follow arthroplasty surgery,(18, 20, 26, 27, 32, 35) which then often requires debridement, administration of intravenous antibiotics, and surgical revision of the implanted device.(12, 15, 21, 28-30) In a recent study, 56% of 193 shoulder revisions had a positive culture, 70% of which grew C. acnes.(30) Despite the relatively common presumed association of C. acnes humeral osteomyelitis with prosthetic infection, infection of the scapula or clavicle secondary to C. acnes is rare.(4, 23, 36) Osteomyelitis of the clavicle involving any organism is also an uncommon event that can arise spontaneously via presumed hematogenous spread, or secondary to open fractures or internal fixation.(6, 33) The most commonly found organism in clavicular osteomyelitis is Staphylococcus aureus.(9) We here report two cases of clavicular infection secondary to C. acnes that were not associated with implants.