Fig. 1.

Time-lapse microscopy images of mCherry-labelled osteoblasts (OBs) exposed to green fluorescent protein (GFP)-labelled USA300 over 14 hours. Rapid bacterial proliferation was observed in USA300-infected OBs between the first and second hours of infection. Administration of 50 μg/ml gentamicin occurred either 30 minutes or four hours postinfection. Gentamicin treatment within the first 30 minutes of infection significantly reduced bacterial burden relative to the untreated and four-hour postinfection treatment groups by one-way, repeated measures ANOVA (p = 0.025). Bacterial burden was reduced in USA300-infected OBs treated with gentamicin four hours postinfection, but to a lesser extent than that in the OBs treated within 30 minutes of infection. ANOVA, analysis of variance. MRSA, methicillin-resistant Staphylococcus aureus.