Antibiotics delivered by an implantable drug pump. A new application for treating osteomyelitis

Safety Profile of Seven-Day Intra-articular Antibiotic Irrigation for the Treatment of Chronic Periprosthetic Joint Infection: A Prospective Randomized Phase II Comparative Study

BACKGROUND

Systemic intravenous antimicrobials yield poor outcomes during treatment of periprosthetic joint infection due to the inability to obtain minimum biofilm eradication concentrations. This study evaluated the safety of a novel method of optimized local delivery of intra-articular antibiotics (IAAs).

METHODS

This was a Phase II, multicenter, prospective randomized trial evaluating safety of a rapid (seven-day) two-stage exchange arthroplasty with IAA irrigation compared to standard two-stage exchange. The Experimental Group received irrigation using 80 mg tobramycin daily with a 2-hour soak, followed by hourly irrigation using 125 mg vancomycin with a 30-minute soak via an intramedullary irrigation device. The Control Group received an antibiotic-loaded cement spacer with vancomycin (average 8.4 g) and tobramycin (average 7.1 g, total 16 g antibiotics). Both groups received 12 weeks of systemic antibiotics following Stage 2. Safety measures included adverse events, peak vancomycin/tobramycin serum concentrations (Experimental Group), blood transfusion, and mortality. There were thirty-seven patients randomized to the Experimental Group and 39 to control. There was no difference in baseline demographics or comorbidities.

RESULTS

There were no antibiotic medication-related adverse events and 2 serious adverse events related to antibiotic instillation. Of 188 vancomycin peak measurements, 69% had detectable serum level concentrations, with all concentrations well below the maximum acceptable trough threshold of 20 μg/mL. Of the 103 tobramycin peak measurements, 45% had detectable levels, with all below the maximum acceptable peak threshold of 18 to 24 μg/mL. There was no difference in blood transfused per subject (Experimental: 655 mL versus Control: 792 mL; P = .4188). There were two (2) deaths in the Experimental Group and four (4) in the control.

CONCLUSIONS

The use of IAA is safe with minimal systemic antibiotic exposure. There was no difference in the rates or severity of serious adverse events between groups. Further research is being conducted to examine treatment efficacy.

Management of chronic osteomyelitis of the femur and tibia: a scoping review

Osteomyelitis refers to an inflammatory process causing bone destruction and necrosis. Managing such a persistent disease is complex, with a number of authors reporting different techniques. This scoping review aims to map and summarize the literature on treatment of chronic femoral and tibial osteomyelitis, in order to improve the reader's understanding of potential treatments and identify areas of further research.The methodological framework of the Joanna Briggs Institute was followed. A computer-based search was conducted in PubMed, EMBASE, MEDLINE, EMCARE and CINAHL, for articles reporting treatment of chronic tibial/femoral osteomyelitis. Two reviewers independently performed title/abstract and full-text screening according to pre-defined criteria.A total of 1230 articles were identified, with 40 finally included. A range of treatments are reported, with the core principles being removal of infected tissue, dead-space management and antibiotic therapy. The majority (84.5%) of patients presented with stage III or IV disease according to the Cierny-Mader classification, and Staphylococcus aureus was the most commonly isolated organism. The proportion of patients achieving remission with no recurrence during follow-up varies from 67.7-100.0%.The majority of studies report excellent outcomes in terms of infection remission and lack of recurrence. However, identifying specific patient or treatment-related factors which may affect outcomes is currently challenging due to the nature of the included studies and unclear reporting of treatment outcomes. It is now important to address this issue and identify such factors using further high-level research methods such as randomized controlled trials and comparative cohort studies. Cite this article: EFORT Open Rev 2021;6:704-715. DOI: 10.1302/2058-5241.6.200136.

Efficacy of moxifloxacin compared to teicoplanin in the treatment of implant-related chronic osteomyelitis in rats

Treatment of implant-related chronic osteomyelitis is often difficult and usually consists of implant removal, extensive surgical debridement, and prolonged antibiotic use. This study was performed to assess the efficacy of moxifloxacin compared to a glycopeptide, teicoplanin in chronic implant-related methicillin-sensitive Staphylococcus aureus (MSSA) osteomyelitis. The left femoral medullar cavities of 60 Wistar male rats were contaminated with 100 µl of 10(8) cfu/ml methicillin-sensitive S. aureus (ATCC 29213) and Kirschner wires were placed into the medulla of the femur. After 6 weeks, rats were randomly divided into five groups. In two groups, the Kirschner wires were removed. Experimental groups were as follows: group 1: contaminated, Kirschner wire inside, received teicoplanin; group 2: contaminated, Kirschner wire removed, received teicoplanin; group 3: contaminated, Kirschner wire inside, received moxifloxacin; group 4: contaminated, Kirschner wire removed, received moxifloxacin; group 5: contaminated, Kirschner wire inside, no antibiotics (control group). Groups 1 and 2 received teicoplanin (20 mg/kg once daily), whereas groups 3 and 4 received moxifloxacin (10 mg/kg twice daily) intraperitoneally for 28 days. At the end of the treatment, animals were sacrificed by inhalation anesthesia with ether and femora were retrieved and bacterial counts (cfu/g) were determined. Bacterial counts in all study groups were significantly reduced relative to the control. The decrease of bacterial counts was more prominent in group 4 compared to group 1 (p = 0.001) and group 2 (p = 0.003). Moxifloxacin therapy is an effective alternative to teicoplanin for chronic implant-related MSSA osteomyelitis.

The preparation of ciprofloxacin hydrochloride-loaded chitosan and pectin microspheres: their evaluation in an animal osteomyelitis model

Ciprofloxacin hydrochloride-loaded microspheres were prepared by a spray-drying method using pectin and chitosan. The effects of different polymers and drug ratios were investigated. The most appropriate carriers were selected by in vitro testing. A rat methicillin-resistant Staphylococcus aureus osteomyelitis model was used to evaluate the effects of the loaded microspheres. The drug was released rapidly from the pectin carrier but this was more sustained in the chitosan formulation.Chitosan microspheres loaded with ciprofloxacin hydrochloride were more effective for the treatment of osteomyelitis than equivalent intramuscular antibiotics.

Effect of varying surface patterns on antibiotic elution from antibiotic-loaded bone cement

In an effort to improve the antibiotic elution characteristics of the prosthesis of antibiotic-loaded acrylic cement, an in vitro study was conducted. Tobramycin-loaded bone cement blocks of three different surface patterns with different surface area-to-volume ratios were used. The elution of tobramycin over a 2-month period was investigated. There was a gradual decline in the tobramycin elution rate over time. The surface pattern with the increased surface area-to-volume ratio showed a significant increase in the tobramycin elution rate over the first week of the study. The surface pattern with ridges but no change in the surface area-to-volume ratio did not result in a statistically significant increase in the tobramycin elution rate.

Pharmacokinetic study of fibrin clot-ciprofloxacin complex: an in vitro and in vivo experimental investigation

We prepared a composite of fibrin clot and ciprofloxacin for use as a biodegradable antibiotic delivery system with sustained effect for the treatment of chronic osteomyelitis. In vitro, ten experiments were performed in which 10 mg of ciprofloxacin were incorporated into 4 ml of fibrin clot. The clots were preserved in nutrient broth and incubated at 37 degrees C for a total of 60 days. Every 24 h a broth specimen was obtained, and the ciprofloxacin concentration was determined by microbiological assay. The maximum level of antibiotic was noted on the first day (49.9 +/- 5.1 mg/l). The ciprofloxacin-fibrin clot complexes usually disintegrated after 60 days. In vivo, the fibrin-ciprofloxacin clots were made as previously described. The composite was implanted in the medullary canal of rabbit tibiae, and the antibiotic concentration was measured in bone, muscle, skin and serum. In all tissues around the implant, the concentration of antibiotic exceeded the minimum inhibitory concentration against the common causative organisms of osteomyelitis for 10 days. The implant caused no systemic side-effects, and it is likely to prove clinically useful as a drug delivery system for treating chronic osteomyelitis.

Combined treatment with antibiotic, heparin and streptokinase--a new approach to the therapy of bacterial osteomyelitis

Combined treatment by continuous intravenous infusion of a selected antibiotic and heparin and/or streptokinase was elaborated as a method of causal, systemic treatment of bacterial osteomyelitis. The aim of the combined treatment was to overcome infection and disturbances in the coagulation and fibrinolysis system which lead to impairment of the bone blood supply and its subsequent necrosis as the main factor in the aetiopathology of osteomyelitis. Between 1969 and 1991, combined treatment was introduced in 63 patients with acute onset disease or with chronic osteomyelitis. Osteomyelitis was located in the mandible in 38 patients and in the long bones in 14 patients. Prior to combined treatment, moderate bone surgery was performed in 21 patients, while 31 patients were excluded from surgery. Combined treatment with an antibiotic and heparin (A+H) was performed in 43 patients, and the other 6 patients had infusion of an antibiotic, streptokinase and heparin (A+S+H). The authors' method of combined treatment offers a new approach and an alternative to routinely-ordered antibiotic therapy and radical surgery, which allow frequent recurrences of the disease, a long-lasting course and severe complications.

Treatment of experimental osteomyelitis with antibiotic-impregnated bone graft substitute

The model of Norden was used to induce osteomyelitis in the left tibia of New Zealand White rabbits. Twenty-one days following inoculation, the animals had primary debridement and then were randomized into one of three treatment groups. Group I received no additional treatment; in Group II, plain hydroxyapatite beads were packed into the defect; and in Group III, gentamicin crobefat-loaded hydroxyapatite beads were packed into the defect. The animals were observed for 40 days after the primary debridement and then were killed. The intensity of infection was determined by swab cultures and quantitative bacterial cultures of the debrided material. At primary debridement, all of the animals in each group were equally infected. At the time of secondary debridement, only the animals in Group III had a statistically significant reduction in infection (p < 0.001). In this study, we demonstrated that an antibiotic-loaded osteoinductive ceramic bead can effectively eliminate bacteria from an osteomyelitic cavity.

Bioerodible polyanhydrides for antibiotic drug delivery: in vivo osteomyelitis treatment in a rat model system

Acute and chronic osteomyelitis can be difficult to treat by conventional means. Current methods of treatment involve the use of systemic antibiotics, the local implantation of non-degradable drug carriers, and surgical débridement. Each method has specific drawbacks. We report on the use of a new controlled release system utilizing gentamicin and bioerodible, biocompatible polymers (polyanhydrides) designed for drug delivery applications for the treatment of clinical osteomyelitis. We compared this system's ability to reduce bacterial levels in infected bone with that of conventional non-degradable delivery systems based on polymethylmethacrylate (PMMA) and gentamicin. Polyanhydride copolymers of bis-carboxyphenoxypropane and sebacic acid P loaded with gentamicin sulfate and PMMA/gentamicin matrices were implanted in the long bones of Sprague-Dawley rats infected with a strain of Staphylococcus aureus. After 3 weeks of implantation, the polymeric delivery devices were removed and quantitative cultures were used to determine bacterial levels in bone. The polyanhydride/gentamicin matrices demonstrated significant degradation over the 3 week implantation period. Levels of bacteria, measured in colony forming units, were significantly lower in bone implanted with the polyanhydride/gentamicin release system than in long bones of control animals without an implant (p < 0.01), of animals with a polyanhydride polymer implant alone (p < 0.01), and of animals with a PMMA/gentamicin implant (p = 0.03). Bioerodible polyanhydrides show promise as a new treatment modality for infections in bone.

Biocompatible implantable antimicrobial release for necrotizing external otitis

The efficacy of a biocompatible, surgically implantable, antimicrobial release system (IARS) as the exclusive antimicrobial therapy of necrotizing external otitis (NEO) was evaluated in six NEO patients. Gentamicin incorporated polymethyl-methacrylate beads were implanted, following surgical debridement and were removed two months later. Post-implantation alleviation of clinical symptoms: pain, periauricular tissue swelling, otorrhoea, eradication of pseudomonal infection (100 per cent) and substantially shortened hospitalization (4-15 days) were the salient results of this therapeutic modality. Three patients recovered. Two patients who died, one of sudden cardiac arrest and the other of paralytic ileus, 15 and 60 days post-operatively while the beads were still implanted, were symptomless. Recurrence was seen in one patient with early bead extrusion. Ipsilateral sensorineural hearing loss (one patient) and external meatal stenosis were the main complications. IARS appears to offer an effective alternative to long-term systemic antibiotic administration for the eradication of NEO-pseudomonal infection in patients who are sensitive, develop resistance, or when quinolone medical treatment has failed or is contra-indicated.

Antibiotic release from an experimental biodegradable bone cement

An experimental biodegradable bone cement [poly(propylene fumarate)-methylmethacrylate] (PPF-MMA) has been compared in vivo with polymethylmethacrylate (PMMA) as a carrier agent for local release of antibiotics. This approach is potentially applicable to the treatment of chronic osteomyelitis where the clinical goal is to achieve sustained high concentrations of antibiotics locally in the infected bone. In our experiments, gentamicin- and vancomycin-impregnated cylindrical PMMA and PPF-MMA cement specimens were implanted subcutaneously in rats, and blood and wound fluid samples were obtained over a 2-week period. Antibiotic levels were determined using immunoassays, and microbiologic activity was confirmed with agar diffusion techniques. The biodegradable PPF-MMA cement achieved and maintained considerably higher wound antibiotic levels than did PMMA cement. Vancomycin levels for the PPF-MMA cement were greater than 20 times those for the PMMA cement at all sampling times from 24 h to 14 days. For both cements, the serum antibiotic concentrations remained safely below maximum levels recommended for parenteral therapy. Mechanical testing of the PPF-MMA cement showed that admixture of 3% by weight of antibiotic did not adversely affect material properties. We conclude that this experimental biodegradable bone cement (PPF-MMA) can be used as a carrier to achieve high sustained local levels and low serum levels of antibiotics. Because it is biodegradable and thus does not require a secondary procedure for removal, it has special potential for use in treatment of chronic osteomyelitis.

Instability of vancomycin in Infusaid drug pump model 100

The implantable Infusaid drug pump model 100 (Shiley Infusaid, Norwood, Mass.) is undergoing trials as a drug delivery system in the treatment of osteomyelitis. This study evaluated the stability of vancomycin (1 mg/ml) incubated at 37 degrees C for 4 weeks in the pump. Both bioassay and high-pressure liquid chromatography data demonstrated a loss of at least 38% of activity over 4 weeks and colloidal precipitation of vancomycin in the pump at the end of the experiment. This study suggests that vancomycin is not stable enough for use in the Infusaid drug pump model 100.