Bacteriophage Dosing and Its Effect on Bacterial Growth Suppression in a Staphylococcus epidermidis Model: An In...

Phages are an emerging therapy in the treatment of prosthetic joint infections, though many challenges remain, including an incomplete understanding of optimal phage dosing.

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.

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).

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.