AIM: Chronic osteomyelitis is a difficult to treat infection requiring prolonged antimicrobial therapy and involving systems of local antimicrobial delivery. Linezolid is a new antimicrobial agent with well documented in vitro activity against gram positive cocci when resistance to other antistaphylococcal agents is present. Few data are present regarding its embedding in local antimicrobial delivery systems and subsequent elution. The elution of linezolid by a polylactic acid (PLA) system was studied.

METHODS: Linezolid was dry-mixed with PLA at a ratio of 1:9, ie 50mg of linezolid were mixed with 450mg PLA. The mixture was diluted with 0,5mL of methanol and placed at the bottom of a cylindrical vial. Two replicas were created and one mL of Mueller-Hinton broth was added over the free solid surface of each mixture. Vials were transferred to a 37°C incubator and broth was replaced every 48h for 11 days. Concentration of linezolid was determined by an HPLC method using a Zorbax Eclipse XDB-C8 column and UV detection.

RESULTS: Mean linezolid concentration at days 1, 3, 5, 7, 9 and 11 was 2778.54 mg/L, 2456.22 mg/L, 668.63 mg/L, 324.86 mg/L, 390.10 mg/L, and 155.28 mg/L respectively.

CONCLUSION: Elution of linezolid by a PLA local delivery system remains very high throughout the period studied. The results are promising for the therapy of staphylococcal chronic osteomyelitis with the use of a PLA local antimicrobial delivery system employing linezolid.