Antibacterial activity of amikacin-, cefotaxime-, and meropenem-impregnated bone cement discs against gram-negative bacteria <i>Pseudomonas aeruginosa</i> and <i>Klebsiella pneumoniae</i>

BACKGROUND: There is an ongoing need to develop new antibiotic-loaded bone cement formulations, including those effective against resistant bacterial strains. Such formulations should create a local antibacterial environment capable of inhibiting bacterial growth and eliminating pathogens without inducing toxic reactions.
AIM: This study aimed to evaluate the antibacterial efficacy of amikacin, cefotaxime, and meropenem impregnated into bone cement–based discs against Gram-negative bacteria Pseudomonas aeruginosa and Klebsiella pneumoniae.
METHODS: This was a single-center, continuous, prospective, non-blinded in vitro experimental study. Reference bacterial strains belonging to two taxonomic groups were used as test cultures: Pseudomonas aeruginosa ATCC 27853 and Klebsiella pneumoniae ATCC 700603. Discs with a diameter of 5 mm and a thickness of 2 mm were prepared from polymethyl methacrylate (PMMA)-based bone cement (Synicem 1). Antibiotics were incorporated into the cement in three weight proportions (groups 1, 2, and 3). The antibacterial effect of antibiotic-impregnated discs against the tested bacterial strains was assessed using the disk diffusion method. The experiment was conducted over six days. Results were recorded at 24, 48, 72, and 144 hours.
RESULTS: After 24 hours, bactericidal activity against P. aeruginosa strains was observed on Petri dishes containing discs impregnated with meropenem, amikacin, and cefotaxime. After 48 hours and during subsequent observation periods, a reduction in the diameter of bacterial growth inhibition zones was noted. For K. pneumoniae strains, no inhibition zone was observed when amikacin-impregnated bone cement was used in groups 1 and 2. A minimal antibacterial effect was observed with the use of discs in group 3. Discs containing cefotaxime exhibited weak antibacterial activity. Meropenem diffusion (groups 2 and 3) and bactericidal effects were observed throughout the entire 6-day period, with the most pronounced antibacterial activity occurring during the first 24 hours.
CONCLUSION: In experiments involving P. aeruginosa, all tested antibiotics demonstrated maximum release during the first 24 hours, regardless of their concentration in the discs. Subsequently, the elution rate decreased and remained stable until the end of the experiment. In experiments with K. pneumoniae, meropenem was the only effective antibiotic during the first day of observation. Among the antibiotics impregnated into PMMA-based discs, only meropenem demonstrated consistent antibacterial activity against both P. aeruginosa and K. pneumoniae, suggesting its potential use for local antibacterial therapy. Further in vitro and in vivo studies are required to determine the optimal antibiotic concentration and clinical efficacy in the prevention and treatment of chronic osteomyelitis.