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

Local Antibiotic Therapy for Open Long Bone Fractures: Appropriate Prophylaxis or Unnecessary Exposure for the Orthopedic Trauma Patient?

INTRODUCTION

Prophylactic local antibiotic therapy (LAbT) to prevent infection in open long bone fracture (OLBF) patients has been in use for many decades despite lack of definitive evidence confirming a beneficial effect. We aimed to evaluate the effect of LAbT on outcomes of OLBF patients on a nationwide scale.

MATERIALS AND METHODS

In this retrospective analysis of 2017-2018 American College of Surgeons-Trauma Quality Improvement Program database, all adult (≥18 years) patients with isolated OLBF (non-extremity-Abbreviated Injury Scale < 3) were included. We excluded early deaths (<24 h) and those who had burns or non-extremity surgery. Outcomes were infectious complications (superficial surgical site infection, deep superficial surgical site infection, osteomyelitis, or sepsis), unplanned return to operating room, and hospital and intensive care unit length of stay (LOS). Patients were stratified into two groups: those who received LAbT and those who did not receive LAbT (No-LAbT). Propensity score matching (1:3) and chi-square tests were performed.

RESULTS

A total of 61,337 isolated OLBF patients were identified, among whom 2,304 patients were matched (LAbT: 576; No-LAbT: 1,728). Both groups were similar in terms of baseline characteristics. Mean age was 43 ± 17 years, 75% were male, 14% had penetrating injuries, and the median extremity-Abbreviated Injury Scale was 1 (1-2). Most common fracture locations were tibia (66%), fibula (49%), femur (24%), and ulna (11%). About 52% of patients underwent external fixation, 79% underwent internal fixation, and 86% underwent surgical debridement. The median time to LAbT was 17 (5-72) h, and the median time to debridement was 7 (3-15) h (85% within 24 h). The LAbT group had similar rates of infectious complications (3.5% vs. 2.5%, P = 0.24) and unplanned return to the operating room (2.3% vs. 2.0%, P = 0.74) compared to the No-LAbT group. Patients who received LAbT had longer hospital LOS (16 [10-29] vs. 14 [9-24] days, P < 0.001) but similar intensive care unit LOS (4 [3-9] vs. 4 [2-7] days, P = 0.19).

CONCLUSIONS

Our findings indicate that prophylactic LAbT for OLBF may not be beneficial over well-established standards of care such as early surgical debridement and systemic antibiotics. Prospective studies evaluating the efficacy, risks, costs, and indications of adjuvant LAbT for OLBF are warranted.

Elution profiles of metronidazole from calcium sulfate beads

BACKGROUND

Antibiotic beads are used to treat local bacterial infections by delivering high drug concentrations to infected tissue.

OBJECTIVES

This study examined the elution characteristics of metronidazole from metronidazole-calcium sulfate (MCa) and metronidazole-calcium-potassium sulfate (MCaK) beads over 20 days and the antibacterial efficacy of the beads after storage.

METHODS

The MCa and MCaK beads were prepared by mixing 250 mg of metronidazole and 10 g of calcium sulfate hemihydrate with water and a 3% potassium sulfate solution, respectively. The beads were placed in phosphate-buffered saline for the elution study. The metronidazole eluents were determined using high-performance liquid chromatography. The microstructures were examined by scanning electron microscopy (SEM), and the antimicrobial activity was evaluated by a microbioassay.

RESULTS

For the 20-day study, the total amount of metronidazole released was greater in the MCa beads than in the MCaK beads by 6.61 ± 0.48 mg (89.11% ± 3.04%) and 4.65 ± 0.36 mg (73.11% ± 4.38%), respectively. The amounts of eluted drugs from the MCa and MCaK beads were higher than the minimum inhibitory concentration at 0.5 µg/mL against anaerobic bacteria at both 20 days and 14 days. SEM showed that calcium crystals on the outer surface had dissolved after elution, and thinner calcium crystals were prominent in the MCaK beads. The MCa and MCaK beads exhibited antibacterial activity after setting, followed by storage at room temperature or 4°C for 21 days.

CONCLUSIONS

The MCa beads could release more drug than the MCaK beads, but all eluted metronidazole amounts were effective in controlling bacterial infections. Both metronidazole beads could be stored at ambient temperature or in a refrigerator.

Treatment of Septic Tenosynovitis and Osteoarthritis in an American White Pekin (Anas platyrhynchos domesticus) with Repeated Intravenous Regional Limb Perfusion and Antibiotic-Impregnated Calcium Sulfate Beads

A 2-year-old female American white pekin (Anas platyrhynchos domesticus) was assessed for a 2-month history of chronic lameness and swelling involving the left leg. Radiographic images of the left leg showed soft tissue swelling of the digits and tarsometatarsus with osteolysis of the tarsometatarsal-phalangeal joint. A complete blood count revealed marked leukocytosis and hyperproteinemia. A Streptococcus species was isolated from a bacterial culture of fluid obtained from the left tarsometatarsal-phalangeal joint. Biweekly intravenous regional limb perfusions of the left leg with ampicillin-sulbactam and amikacin were performed on the patient. Despite initial improvement in left leg lameness and swelling, follow-up radiographic images showed progressive osteolysis of the tarsometatarsal-phalangeal joint and associated digits. Surgical placement of antibiotic-impregnated calcium sulfate beads into the left tarsometatarsal-phalangeal joint was next performed with concurrent, repeated intravenous regional limb perfusion using the same antibiotic. Following the placement of antibiotic-impregnated beads and continued intravenous regional limb perfusion, the duck had decreased lameness and swelling of the left leg. Repeated antibiotic treatment through intravenous regional limb perfusion and concurrent placement of antibiotic-impregnated calcium sulfate beads is a practical treatment option for complicated distal limb infections in avian species. This therapeutic protocol has great potential in treating aggressive distal leg infections in many avian species because regional limb perfusion alone may not penetrate the joint adequately to achieve complete resolution of infection.