Abstract
BACKGROUND: Phages are an emerging therapy in the treatment of prosthetic joint infections, though many challenges remain, including an incomplete understanding of optimal phage dosing.
MATERIALS AND METHODS: We performed an in vitro assessment of how phage dosing as measured by multiplicity of infection (MOI) impacts bacterial growth in planktonic and biofilm conditions using a Staphylococcus epidermidis model. Staphylococcus epidermidis ATCC 35984 was combined in planktonic and biofilm forms with phage vB_SepM_Alex at varying concentrations, and growth was monitored via spectrophotometry.
RESULTS: Planktonic bacterial growth was significantly higher when MOI ≤ 0.01 compared with MOI ≥ 10 (p < 0.05). Biofilms with phage dosing at ≤ 104 plaque-forming units (PFU)/mL had significantly greater spectrophotometer readings than those dosed at 1010 PFU/mL (p < 0.05).
CONCLUSIONS: Our findings suggest lower, not higher, phage dosing is associated with greater bacterial persistence. Our study helps inform the dosing and delivery of this alternative form of antibiosis.