Antibiotic-loaded Polymethylmethacrylate Beads Research Articles

Local Antibiotic Delivery Systems in the Surgical Treatment of Diabetic Foot Osteomyelitis: Again, No Benefit?

This retrospective study aimed to compare the outcomes and healing parameters of 3 groups of surgical treatment combined with and without local antibiotic administration in diabetic foot osteomyelitis (DFO). Overall, 25 patients with DFO who met the criteria were included in the study. Surgical debridement was used with systemic antibiotic administration alone (group A; n = 8) or combined with local application of antibiotic-loaded polymethylmethacrylate beads (group B; n = 9) or antibiotic-loaded hydroxyapatite and calcium sulfate beads (group C; n = 8). In total, 87.5% patients in group A, 100% in group B, and 87.5% in group C healed (P = .543). Median time to healing was 17 weeks in group A, 18 weeks in group B, and 19 weeks in group C (P = .094). One patient (12.5%) in group A was amputated. DFO recurrence rate was 12.5% in group A and 12.5% in group C (P = .543). Median hospitalization was 9 days in group A, 8 days in group B, and 9 days in group C (P = .081). In conclusion, adjunctive local antibiotic therapy was not shown to improve outcomes in surgically treated DFO.

Antibiotic-Loaded Polymethylmethacrylate Beads and Spacers in Treatment of Orthopedic Infections and the Role of Biofilm Formation.

Polymethylmethacrylate (PMMA) also referred as (acrylic) bone cement is a non-degradable biomaterial that has been used in clinical orthopedic practice for several decades. PMMA can be used in a plain formulation, but is often used in an antibiotic-loaded formulation in (primary and revision) arthroplasty and in treatment of orthopedic infections as prosthetic joint infections (PJI) and chronic osteomyelitis. In treatment of PJIs antibiotic-loaded PMMA is often used as a carrier material for local antibiotic delivery in addition to treatment with systemic antibiotics. In this case, the antibiotic-loaded PMMA is often used as a spacer or as a bead chain. Since the introduction of PMMA as an antibiotic carrier there is a tremendous amount of scientific and clinical papers published, which studied numerous different aspects of antibiotic-loaded PMMA. This paper will review the research regarding basic principles of antibiotic-loaded PMMA as mechanism of action, antibiotic-release capacities, choice of antibiotics and influences on mechanical properties of PMMA. Subsequently, concerns regarding the application of antibiotic-loaded PMMA, biofilm formation, antibiotic resistance and local or systemic toxicity will be discussed. In addition to these subjects, the role of antibiotic loaded PMMA in clinical treatment of PJIs and chronic osteomyelitis is discussed in the final part of this paper.

Antibiotic-loaded polymethylmethacrylate beads for the treatment of extracavitary vascular surgical site infections

This study assessed the efficacy of antibiotic-loaded polymethylmethacrylate (PMMA) beads in the treatment of lower extremity vascular surgical site infections (VSSIs). This was a retrospective review of all patients with a VSSI of a lower extremity bypass treated with antibiotic-loaded PMMA beads and culture-specific antibiotics during a 4.5-year period. Data collected included patient demographics, comorbidities, site of initial graft infection, symptoms and signs at presentation, initial and additional surgical debridement, wound culture results, type of antibiotic beads implanted, and graft treatment strategy, comprising conduit preservation or in situ replacement, with associated soft tissue management by muscle flap or vacuum-assisted closure. Primary outcome measures included death, recurrent infection, and limb salvage. Forty patients developed 42 extracavitary lower extremity VSSIs (bilateral groin infections in two). Patients were treated according to our treatment algorithm with antibiotic-impregnated PMMA beads. Previous reconstructions included nine aortofemoral bypasses (groin infection only), 20 infrainguinal bypasses, five extra-anatomic bypasses, five femoral interpositions, two combined inflow-outflow bypass procedures, and one patch angioplasty with VSSI. Cultures isolated 59 pathogens (39 gram-positive, 18 gram-negative, 2 Candida spp). Methicillin-resistant Staphylococcus aureus was cultured from 10 VSSs (23.8%) overall and from 27.7% of those patients with attempted graft preservation or in situ reconstructions. Two patients (4.8%) had no growth despite clinical signs of infection. Repeat VSS exploration and culture results led to an average of 1.4 bead replacements before definitive treatment. Final treatment strategy included graft preservation of patent bypasses in 28, partial graft excision with in situ replacement in eight, graft removal only with residual graft remaining at implant site (ie, incorporated anastomotic conduit, 11.9%) in five, and extra-anatomic reconstruction in one. Sartorius muscle flap was performed in 14 groin infections (37.8%). The 30-day mortality was 0%, and limb loss was 7.1% (n = 3). At the median follow-up of 17 months, the limb loss was 21.4% and the recurrent infection rate was 19.4% (seven of 36) in those with attempted graft preservation or in situ replacement. Antibiotic-loaded PMMA beads may serve as an adjunct in the management of VSSIs and may also expand treatment options for graft preservation or in situ reconstruction, with expected recurrent infection rate approaching 20%. Further experience with this adjunct may help elucidate its role in the management of this complicated problem, including the need for bead exchanges, until perigraft cultures are free of microbes.

Antibiotic-Loaded Polymethylmethacrylate Beads for the Treatment of Extracavitary Prosthetic Vascular Graft Infections: Revisited

Antibiotic-Loaded Polymethylmethacrylate Beads for the Treatment of Extracavitary Prosthetic Vascular Graft Infections: Revisited

Use of antibiotic-loaded polymethylmethacrylate beads for the treatment of extracavitary prosthetic vascular graft infections

This study was conducted to assess the efficacy of antibiotic-loaded polymethylmethacrylate (PMMA) beads in the management of lower extremity extracavitary prosthetic arterial graft infection. This was a retrospective review of 34 patients treated for vascular surgical site (VSS) infections involving 36 prosthetic lower extremity arterial bypasses using antibiotic-loaded PMMA beads and culture-specific parenteral antibiotics for 4 to 6 weeks. Sites of graft infection were explored, debrided, and cultured. As determined from the results of Gram's stains of VSS purulence, PMMA powder was polymerized with an antibiotic (vancomycin, daptomycin, or tobramycin/gentamicin, or a combination), molded into a chain of beads, and implanted adjacent to the infected graft after debridement and pulsed-spray antibacterial lavage. All wounds were closed primarily with planned exploration to verify sterilization before a graft preservation or in situ replacement procedure. Treatment outcomes, including wound sterilization, were analyzed based on tissue culture isolates, procedures for persistent infection, and freedom from graft infection. Cultures isolated 42 pathogens, (32 gram-positive, 9 gram-negative, 1 Candida albicans) with methicillin-resistant Staphylococcus aureus (MRSA) cultured from 16 (44%) of 36 surgical site infections. As determined from the initial operative Gram's stain or a prior culture result, vancomycin PMMA beads were implanted in 29 of 36 VSS infections at the first procedure; daptomycin (n = 4) or tobramycin (n = 3) beads were implanted in the rest. Repeat VSS exploration and culture results led to an average of 2.5 antibiotic bead replacements before definitive treatment. A sterile (no growth on tissue culture) VSS was achieved in 87% of cases before a graft preservation (n = 16) or in-situ replacement of an infected graft (n = 20) procedure. No patient deaths occurred. Early and late limb salvage was 100%. Infection recurred in 4 (11%) VSSs during a mean 23-month follow-up period, one within 3 months owing to unrecognized bowel injury associated with in situ replacement of an aortofemoral graft limb. Antibiotic-loaded PMMA beads may be a useful adjunct in the contemporary surgical management of VSS infection involving a prosthetic graft. Wound sterilization was achieved in most VSSs before graft preservation or an in-situ replacement procedure, including infections caused by MRSA, a pathogen isolated in half of the extracavitary prosthetic graft infections. This preliminary trial shows the potential benefit of this new technique, but further study is required to prove efficacy.

Use of Antibiotic-Loaded Polymethyl Methacrylate Beads in the Management of Musculoskeletal Sepsis — A Retrospective Study

To assess the use of antibiotic-loaded polymethyl methacrylate beads in the management of chronic osteomyelitis of different aetiologies: infected osteosynthesis, infected open fractures, and haematogenous osteomyelitis. Records of 49 patients with chronic osteomyelitis who were treated at Department of Orthopaedics, Kasturba Medical College, from 1995 to 1999 were studied retrospectively. The diagnosis of chronic osteomyelitis was made on the basis of clinical and radiographic features. Of the 49 patients, 4 had haematogenous osteomyelitis, which later proved to be tuberculosis, and were thus excluded. Antibiotic-loaded acrylic beads were implanted in the remaining patients after thorough debridement. The implant was removed primarily in 16 patients with infected osteosynthesis, who then underwent decompression and sequestrectomy. All wounds were closed primarily. Peri-operative antibiotics were given for 7 days. Beads were removed at the end of 3 weeks followed by bone grafting in 26 patients. Patients were followed up for an average period of 3.7 years. The infective organisms were sensitive to gentamycin in 26 cases and resistant in 19 cases; 14 cases were sensitive to cefuroxime, 11 to cloxacillin, 8 to ampicillin, and 5 to cotrimoxazole. Seven cases were resistant to all antibiotics tested. Of the 19 patients with gentamycin-resistant infection, only one had a poor result. No adverse systemic side-effects such as ototoxicity or nephrotoxicity were seen. Infection did not recur in 39 patients, but 6 patients had low-grade persistent infection at the last follow-up visit. In chronic infections, especially those following osteosynthesis, antibiotic beads are a valuable adjuvant. The most valuable advantage is that the wound can be closed primarily, thereby reducing the incidence of nosocomial infections and requirement of nursing care.

Residual gentamicin-release from antibiotic-loaded polymethylmethacrylate beads after 5 years of implantation

In infected joint arthroplasty, high local levels of antibiotics are achieved through temporary implantation of non-biodegradable gentamicin-loaded polymethylmethacrylate beads. Despite their antibiotic release, these beads act as a biomaterial surface to which bacteria preferentially adhere, grow and potentially develop antibiotic resistance. In routine clinical practice, these beads are removed after 14 days, but for a variety of reasons, we were confronted with a patient in which these beads were left in situ for 5 years. Retrieval of gentamicin-loaded beads from this patient constituted an exceptional case to study the effects of long-term implantation on potentially colonizing microflora and gentamicin release. Gentamicin-release test revealed residual antibiotic release after being 5 years in situ and extensive microbiological sampling resulted in recovery of a gentamicin-resistant staphylococcal strain from the bead surface. This case emphasizes the importance of developing biodegradable antibiotic-loaded beads as an antibiotic delivery system.