Lactoferrin enhances the antibiotic treatment of Staphylococcus aureus in bone infection.

Lactoferrin (Lf), we have previously shown, has therapeutic potential in the field of skeletal regenerative medicine demonstrating its potent stimulating effects on bone growth. Recently, we have identified bovine lactoferrin (bLf) as a factor that also enhances antibiotic killing of Staphylococcus aureus (S. aureus). Biofilms are associated with around 65% of all infections and 80% of chronic infections. One feature of biofilm infection is tolerance to antibiotics due to the survival of a subpopulation of biofilm bacteria, where laboratory tests on planktonic cells indicate susceptibility. Tolerance is seen in bone infections of osteomyelitis and prosthetic joints, where methicillin-susceptible S. aureus (MSSA) strains predominate, but where treatments with the frontline penicillinase-resistant antibiotic cefazolin (CEF) can be ineffective. In vitro-grown biofilms of MSSA are 1000-fold more tolerant to CEF but can be eradicated by CEF at 10x minimal inhibitory concentration in the presence of bLf. Bone infection can impede blood circulation within the bone, leading to bone death. Lf as a potent stimulator of bone growth adds to its appeal as a treatment for bone infections.