Calcium sulfate antibiotic‐impregnated bead implantation for deep surgical site infection associated with orthopedic surgery in small animals

Abstract

Objective: To report the outcomes and complications associated with antibiotic-impregnated calcium sulfate beads for prevention and treatment of orthopedic-related surgical site infection (SSI) in companion animals.Study design: Retrospective case series. Animals: Client-owned cats (n = 2) and dogs (n = 14).Methods: Medical records of 16 cases in which implantation of antibioticimpregnated calcium sulfate beads was performed for the prevention or treatment of SSI were reviewed. Information collected included signalment, prior surgery, reason for bead placement, antibiotics used, bacterial culture results, and clinical outcomes.Results: Surgical site infection resolved in six of 10 animals treated therapeutically and did not occur in six of six animals treated prophylactically. Susceptibility of the causative bacteria to the antibiotic implanted was confirmed in five of six cases with resolved SSI treated therapeutically but in only one of four cases with unresolved SSI treated therapeutically. Complications directly related to bead placement were evident in only one case in which beads extruded from external skeletal fixator pin tracts 7 days after implantation. At final follow-up, 11 of 12 animals without SSI had satisfactory limb use and no clinical, cytologic, or radiographic evidence of infection. Conclusion:Implantation was well tolerated. Resolution of SSI was inconsistent; however, when bacteria were susceptible to the antibiotic implanted, SSI resolved in all but one case.Clinical significance: Antibiotic-impregnated calcium sulfate beads could be considered for prevention or treatment of orthopedic SSI in small animals. A prospective clinical study is required to obtain additional information, including the value of preoperative bacterial culture.

Pancarpal Arthrodesis Using Antibiotic–Impregnated Calcium Sulfate Beads in a Dog with Septic Arthritis and Osteomyelitis

“…8 Choosing the appropriate antibiotic-impregnated for local therapy should ideally be guided by culture and sensitivity results. 6 8 In this case, a multiresistant Proteus sp. and Staphylococcus sp.…”

“…AICS beads have been used as an effective treatment for chronic osteomyelitis in humans, 21 and have recently been reported in veterinary patients. 6,11 Calcium sulfate has been reported as an effective bone graft substitute and as an expander when combined with autogenous bone graft. 22,23 Calcium sulfate is osteoconductive, providing a scaffold for new bone formation and a supportive environment for the ingrowth of new blood vessels and osteogenic cells.…”

“…The use of local antibiotic medication therapy, either prophylactic or therapeutic, is an area of increasing interest in veterinary medicine. 6,7 Potential advantages of local antibiotic medication delivery include increased antibiotic concentration at the surgical site, increased penetration of biofilms, combined with reduced systemic absorption and therefore reduced systemic toxicity. 8 The delivery of local antibiotic-impregnated therapy in veterinary patients has been reported using antibiotic-impregnated cements, calcium sulfate beads, hydrogels, and sponges.…”

Bead size has a greater effect on in vitro elution from antimicrobial-impregnated calcium sulfate beads than drug concentration

“…21 The primary advantage of CaSO 4 beads over polymethylmethacrylate (PMMA), which historically was the primary AIM used clinically, is that CaSO 4 beads are bioabsorbable. 16,17,21,27,28 As the CaSO 4 erodes and is absorbed by the body, any retained antimicrobial will be completely released, negating the retention of the drug deep within the matrix and prolonging elution of the drug until complete absorption of the bead occurs. 17,21 In contrast to implantation into living tissue, minimal resorption of the beads within the test tube was observed throughout the study period.…”

“…3,[25][26][27] It is difficult to compare outcomes across studies and clinical reports, because the AIMs are created according to study-specific protocols or practitioner discretion, with different drug concentrations and dosing. 28 The purpose of this study is to examine the effect that different bead configurations have on antimicrobial elution. Specifically, different bead sizes and changes in antimicrobial concentrations within those beads were evaluated in terms of their effect on elution of amikacin.…”