Antimicrobial activity of gentamicin and vancomycin combination in joint fluids after antibiotic-loaded cement spacer implantation in two-stage revision surgery.

Gentamicin (G) and vancomycin (V) concentrations in drainage fluids obtained from patients during the first 24 hours afterimplantation of antibiotic-loaded polymethylmethacrylate (PMMA) spacers in two-stage revision of infected total hip arthroplastywere studied.Theinhibitory activity of drainage fluids against differentmultiresistant clinical isolates was investigated aswell. Sevenhips were treated by implantation of industrial G-loaded spacers. Vancomycin was added by manually mixing with PMMA bonecement. Serum and drainage fluid samples were collected 1, 4, and 24 hours after spacer implantation. Antibiotics concentrationsand drains bactericidal titer of combination were determined against multiresistant staphylococcal strains. The release of G andV from PMMA cement at the site of infection was prompt and effective. Serum levels were below the limit of detection.The localrelease kinetics of G and V from PMMA cement was similar, exerting a pronounced, combined inhibitory effect in the implantsite. The inhibitory activity of drainage fluids showed substantial intersubject variability related to antibiotic concentrations anddiffered according to the pathogens tested. Gentamicin and vancomycin were released from temporary hip spacers at bactericidalconcentrations, and their use in combination exerted strong inhibition against methicillin-resistant S. aureus and CoagulaseNegative Staphylococci strains.