Suppression of Staphylococcus aureus biofilm formation under a short-term impact of low-intensity direct current in vitro and in a rat model of implant-associated osteomyelitis

Objectives: We investigated the effect of short-term low-intensity direct current (LIDC) on Staphylococcus aureus.

Materials and methods: The reference strain of S. aureus was used. Experiments were performed in agar culture and on a model of rat's femur osteomyelitis. K-wires were used as electrodes. The exposure to LIDC of 150 μA continued for one minute. In vitro exposure was performed once. In vivo group 1 was a control group. Osteomyelitis was modeled in three groups but only groups 3 and 4 were exposed to LIDC four times: either from day 1 or from day 7 post-surgery. The effect was evaluated on day 21. Microbiological, histological, scanning electron, and light microscopy methods were used for evaluation of the LIDC effect.

Results: Bacteria diameter, oblongness, and division increased 15 min after LIDC exposure in the culture around the cathode. After 24 hr, the amount of exomatrix was lower than in the control test, and the cell diameter and roundness increased. Similar changes around the anode were less pronounced. In vivo, biofilm formation on the intramedullary wire cathode was suppressed in group 3. In group 4, detachment and destruction of the biofilm were observed. The formation of S. aureus microcolonies was suppressed, and the adhesion of fibroblasts and immune cells was activated. LIDC did not stop the development of the osteomyelitis process.

Conclusion: Short-term exposure to LIDC suppresses S. aureus biofilm formation on the implant cathode surface in the acute and early postoperative period but does not have an impact on the development of osteomyelitis.