To investigate the efficacy of biomaterials with antibacterial properties in inhibiting the growth of microorganisms commonly associated with infections in orthopedic implants.

Antibiotics released from nanocrystalline hydroxyapatite with calcium sulfate (HCS), calcium sulfate (CaSO₄), and polymethylmethacrylate (PMMA) beads were tested against ATCC strains (ATCC29213, ATCC12228, ATCC6919, ATCC47085) and clinical isolates of Staphylococcus aureus (SA), Staphylococcus epidermidis (SE), Pseudomonas aeruginosa (PSA), and Cutibacterium acnes (CA), including multidrug-resistant and susceptible strains. Carriers were loaded with gentamicin (G), vancomycin (V), or gentamicin plus vancomycin (G+V). Inhibition zone (ZOI) assays determined antibiotic release and potency over 1 to 15 days (D1–D15). The Biofilm-Oriented Antiseptic Test (BOAT) was used to assess biofilm suppression after 24-hour exposure to antibiotic-loaded beads.

Bioceramics (CaSO₄ and HCS) showed greater potency during early phases (D1–D3) (p < 0.05) against Staphylococcus spp., especially for G+V combinations. Between D1–D5, the ZOI differences between bioceramics and PMMA were no longer statistically significant, suggesting initial efficacy differences diminish over time. At later stages (D5–D15), PMMA exhibited larger ZOIs compared to bioceramics (p < 0.05) for most strains. CaSO₄ loaded with V maintained a larger ZOI up to D7 versus PMMA for MRSA (p < 0.05). No statistical differences were found between CaSO₄ and HCS for SA. G+V elution in both bioceramics and PMMA significantly improved ZOIs for SE and CA strains (p < 0.05). There were no significant ZOI differences between carriers for PSA strains; by D5, no inhibition was observed for PSA with any material. For CA, bioceramics tended to yield larger ZOIs. BOAT demonstrated optical density inhibition for all strains except MRSA exposed to G alone and CA strains.

Both bioceramics and PMMA beads acted as effective carriers; however, greater antimicrobial elution and biofilm eradication during early phases (D1–D5) were observed with bioceramics, while PMMA showed superior activity at later stages (D5–D15).