Antibacterial action of lysozyme against osteomyelitis agents: S. aureus and S. epidermidis

Introduction The use of lysozyme as a bactericidal agent against the leading pathogens of chronic osteomyelitis can become an alternative or supplement to existing antibacterial drugs. Purpose To study the antibacterial effect of lysozyme against clinical strains of Staphylococcus aureus and Staphylococcus epidermidis Materials and methods Control strains of Staphylococcus aureus (ATCC 25923), Staphylococcus epidermidis (ATCC 14990) and clinical strains (n = 48), including MRSA (n = 6) and MRSE (n = 6), isolated from wounds and fistulas of patients with chronic osteomyelitis were used as test cultures. The antibacterial effect of lysozyme was assessed using the disk diffusion method. Results Lysozyme exhibited bactericidal activity against control strains of S. aureus and S. epidermidis, the growth inhibition zone of bacteria was 11–12 mm. Among clinical strains of S. aureus, 87.5 % were sensitive to lysozyme, the growth inhibition zone diameter was 9–13 mm. No bactericidal effect was observed against three strains of S. aureus, including two MRSAs, and continuous bacterial growth was observed around the disk. Among strains of S. epidermidis, the antibacterial activity of lysozyme was observed against 79.2 % of isolates, the growth inhibition diameter was 8–11 mm. Resistance of three MRSE strains to lysozyme was noted. Lysozyme enhanced the effect of vancomycin and cefoxitin against methicillin-sensitive staphylococci and norfloxacin and vancomycin against methicillin-resistant staphylococci. Discussion Despite the inhibitory effect found, the use of lysozyme alone may be limited due to its possible degradation by proteases, as well as some immunogenicity. There are studies on the synergism of the combined action of lysozyme with various antibiotics on gram-positive and gram-negative bacteria. The data obtained in our experiment showed an increased antibacterial effect by the combined action of antibiotics and lysozyme against the leading causative agents of osteomyelitis. Conclusion It has been established that lysozyme has an antibacterial effect against clinical strains of S. aureus, S. epidermidis, including MRSA and MRSE, isolated from wounds of patients with chronic osteomyelitis. An increased antibacterial effect is observed by a combined action of lysozyme with cefotaxime, norfloxacin and vancomycin.