Antibacterial Efficacy of Hyaluronic Acid and in Combination with Mupirocin in Rats' Burns: An in Vivo and in Vitro Bacterial Load Reduction

Background: Burn wound infections are complicated by microbial colonisation, biofilm formation, and invasive progression. Hyaluronic acid (HA) provides a protective barrier against external contaminants, while mupirocin (pseudomonic acid A) inhibits bacterial protein synthesis by targeting isoleucyl-tRNA synthetase. The objective: evaluate the antibacterial activity of HA gel alone and in combination with mupirocin (MUP+HA) by measuring colony-forming units (CFUs) and zone of inhibition (ZOI) against bacteria isolated from burn wounds in a rat model. Materials and Methods: A standardized full-thickness burn (10 mm diameter) was induced on the dorsal skin of rats using a stainless-steel rod heated to 100°C and applied for 15 seconds. Bacterial samples were collected on day 7 and cultured on nutrient and Mueller–Hinton agar. Antibacterial efficacy was assessed through CFU quantification and the Kirby–Bauer disk diffusion method. Results: The MUP+HA gel group showed a highly significant reduction in CFUs compared with the negative control and HA groups (P ≤ 0.001). All treated groups differed significantly from the control (P ≤ 0.001). The MUP+HA gel also produced a significantly larger ZOI than HA alone. Conclusion: The MUP+HA combination gel demonstrated superior antibacterial efficacy and a complementary effect, whereas HA alone showed limited activity.