The Electricidal Effect Is Active in an Experimental Model of Staphylococcus epidermidis Chronic Foreign Body Osteomyelitis

Treatment with low-amperage (200 mu A) electrical current was compared to intravenous doxycycline treatment or no treatment in a rabbit model of Staphylococcus epidermidis chronic foreign body osteomyelitis to determine if the electricidal effect is active in vivo. A stainless steel implant and 10(4) CFU of planktonic S. epidermidis were placed into the medullary cavity of the tibia. Four weeks later, rabbits were assigned to one of three groups with treatment administered for 21 days. The groups included those receiving no treatment (n = 10), intravenous doxycycline ( n = 14; 8 mg/kg of body weight three times per day), and electrical current ( n = 15; 200 mu A continuous delivery). Following treatment, rabbits were sacrificed and the tibias quantitatively cultured. Bacterial load was significantly reduced in the doxycycline ( median, 2.55 [ range, 0.50 to 6.13] log(10) CFU/g of bone) and electrical-current ( median, 1.09 [ range, 0.50 to 2.99] log(10) CFU/g of bone) groups, compared to the level for the control group ( median, 4.16 [ range, 3.70 to 5.66] log(10) CFU/g of bone) (P < 0.0001). Moreover, treatment with electrical current was statistically significantly more efficacious (P = 0.035) than doxycycline treatment. The electricidal effect ( the bactericidal activity of low-amperage electrical current against bacterial biofilms) is active in vivo in the treatment of experimental S. epidermidis chronic foreign body osteomyelitis.