In vitro mixing formulas for antimicrobial calcium sulfate beads for point-of-care applications: an additional update to formulas

This communication updates a previous report describing mixing formulas for antimicrobial agents into a synthetic, dissolvable calcium sulfate (CaSO₄) product to create small-sized beads (3-6 mm). Antimicrobial-loaded calcium sulfate (ALCS) beads are applied as surgeon-directed, point-of-care use in cases of periprosthetic joint infection (PJI), fracture-related infection (FRI), and other related bone site infections. This treatment technique has been utilized more frequently in the last decade to combat microbial musculoskeletal infections (MSIs). With the widening spectrum of identified microbes encountered in MSIs, we have provided additional antimicrobial formulas to be used singularly and in combination using our in vitro mixing lab protocol previously published. This communication reports 20 additional agents/combinations tested using our protocol to arrive at a standard mix formula or, when necessary, a modified mixing method. Most mixing formulas derived were for antimicrobials effective against fungi and mycobacterium species.