Are anidulafungin or voriconazole released from polymethylmethacrylate in vitro?

Osteoarticular Mycoses

Osteoarticular mycoses are chronic debilitating infections that require extended courses of antifungal therapy and may warrant expert surgical intervention. As there has been no comprehensive review of these diseases, the International Consortium for Osteoarticular Mycoses prepared a definitive treatise for this important class of infections. Among the etiologies of osteoarticular mycoses are Candida spp., Aspergillus spp., Mucorales, dematiaceous fungi, non-Aspergillus hyaline molds, and endemic mycoses, including those caused by Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides species. This review analyzes the history, epidemiology, pathogenesis, clinical manifestations, diagnostic approaches, inflammatory biomarkers, diagnostic imaging modalities, treatments, and outcomes of osteomyelitis and septic arthritis caused by these organisms. Candida osteomyelitis and Candida arthritis are associated with greater events of hematogenous dissemination than those of most other osteoarticular mycoses. Traumatic inoculation is more commonly associated with osteoarticular mycoses caused by Aspergillus and non-Aspergillus molds. Synovial fluid cultures are highly sensitive in the detection of Candida and Aspergillus arthritis. Relapsed infection, particularly in Candida arthritis, may develop in relation to an inadequate duration of therapy. Overall mortality reflects survival from disseminated infection and underlying host factors.

Antifungal-Loaded Acrylic Bone Cement in the Treatment of Periprosthetic Hip and Knee Joint Infections: A Review

Little is known about the clinical use of antifungal-loaded acrylic bone cement in the treatment of periprosthetic hip and knee joint infections (PJIs). Hence, we performed a literature search using PubMed/MEDLINE from inception until December 2021. Search terms were “cement” in combination with 13 antifungal agents. A total of 10 published reports were identified, which described 11 patients and 12 joints in which antifungal-loaded cement was employed. All studies were case reports or case series, and no randomized controlled trials were identified. In 6 of 11 patients, predisposing comorbidities regarding the emergence of a fungal PJI were present. The majority of the studies reported on infections caused by Candida species. In six cases (seven joints), the cement was solely impregnated with an antifungal, but no antibiotic agent (amphotericin B, voriconazole, and fluconazole). In the other five joints, the cement was impregnated with both antibiotic(s) and antifungals. Great discrepancies were seen regarding the exact loading dose. Four studies investigated the local elution of antifungal agents in the early postoperative period and observed a local release of antifungals in vivo. We conclude that there is a paucity of data pertaining to the clinical use of antifungal-loaded bone cement, and no studies have assessed the clinical efficacy of such procedures. Future studies are urgently required to evaluate this use of antifungals in PJI.

Management of osteoarticular fungal infections in the setting of immunodeficiency

Introduction: Osteoarticular fungal infections (OAFIs) complicate the clinical course of high-risk patients, including immunosuppressed individuals. Their management, however, despite being intricate, is governed by evidence arising from sub-optimal quality research, such as case series. Guidelines are scarce and when present result in recommendations based on low quality evidence. Furthermore, the differences between the management of immunocompromised and immunocompetent patients are not distinct. This is a narrative review after a literature search in PubMed, up to November 2019.Areas covered: The major fungal groups causing osteomyelitis and/or arthritis are Candida spp., Aspergillus spp., non-Aspergillus filamentous fungi, non-Candida yeasts and endemic dimorphic fungi. Their epidemiology is briefly analyzed with emphasis on immunodeficiency and other risk factors. Management of OAFIs includes appropriate antifungal drug therapy (liposomal amphotericin B, triazoles or echinocandins), local surgery and immunotherapy for primary immunodeficiencies. Cessation of immunosuppressive drugs is also mandated.Expert opinion: Management of OAFIs includes affordable and available options and approaches. However, research on therapeutic practices is urgently required to be further improved, due to the rarity of affected patients. Evolution is expected to translate into novel antifungal drugs, less invasive and precise surgical approaches and targeted enhancement of immunoregulatory pathways in defense of challenging fungal pathogens.

Diagnosis and Management of Fungal Periprosthetic Joint Infections

Fungal periprosthetic joint infection (PJI) is a devastating complication because it can be difficult to diagnose, manage, and eradicate. Fungal PJI treatment requires a systematic approach. Increased awareness is essential when patients with painful arthroplasties present with immunosuppression, significant comorbidities, multiple surgeries, and history of drug use. Every suspected fungal PJI should be promptly diagnosed using readily available serum and synovial fluid markers. Surgical management involves débridement, antibiotics, and implant retention, one-stage exchange arthroplasty, prosthetic articulating spacers, and two-stage exchange arthroplasty. Because mycotic infections develop robust biofilms, the utility of débridement, antibiotics, and implant retention and one-stage revisions seem limited. A thorough irrigation and débridement is essential to decrease infection burden. Adjunctive local and systemic antifungal therapy is critical, although the agent choice and duration should be tailored appropriately. Future high-quality studies are needed to develop standardized guidelines for the management of fungal PJI.

Successful Release of Voriconazole and Flavonoids from MAPLE Deposited Bioactive Surfaces

We explored the potential of biomimetic thin films fabricated by means of matrix-assisted pulsed laser evaporation (MAPLE) for releasing combinations of active substances represented by flavonoids (quercetin dihydrate and resveratrol) and antifungal compounds (amphotericin B and voriconazole) embedded in a polyvinylpyrrolidone biopolymer; the antifungal activity of the film components was evaluated using in vitro microbiological assays. Thin films were deposited using a pulsed KrF* excimer laser source which were structurally characterized using atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). High-quality thin films with chemical structures similar to dropcast ones were created using an optimum laser fluence of ~80 mJ/cm2. Bioactive substances were included within the polymer thin films using the MAPLE technique. The results of the in vitro microbiology assay, which utilized a modified disk diffusion approach and were performed using two fungal strains (Candida albicans American Type Culture Collection (ATCC) 90028 and Candida parapsilosis American Type Culture Collection (ATCC) 22019), revealed that voriconazole was released in an active form from the polyvinylpyrrolidone matrix. The results of this study show that the MAPLE-deposited bioactive thin films have a promising potential for use in designing combination devices, such as drug delivery devices, and medical device surfaces with antifungal activity.

Oritavancin polymethylmethacrylate (PMMA)-compressive strength testing and in vitro elution

Background

Polymethylmethacrylate (PMMA) is used for local antimicrobial delivery in orthopedic infection. Oritavancin is a long half-life lipoglycopeptide with broad activity against Gram-positive bacteria. Herein, we addressed if 7.5% w/w oritavancin mixed into PMMA affects PMMA strength and whether it elutes from PMMA, compared to vancomycin.

Methods

Elution was assessed by placing an oritavancin- or vancomycin-loaded bead in a flow system with human plasma. Compressive strength of bland compared to oritavancin- or vancomycin-loaded PMMA was assessed after 0, 3, and 7 days of soaking in 1 ml of pooled normal human plasma at 37 °C, by testing to failure in axial compression using a servo-hydraulic testing machine.

Results

Median compressive strength on days 0, 3, and 7 for bland PMMA compared to oritavancin- or vancomycin-loaded PMMA was 80.1, 79.4, and 72.4 MPa, respectively; 93.3, 86.4, and 65.3 MPa, respectively; and 97.8, 82.7, and 65.9 MPa, respectively. Oritavancin reduced PMMA compressive strength after 3 and 7 days (P = 0.0250 and 0.0039, respectively), whereas vancomycin reduced the PMMA compressive strength after 0, 3, and 7 days (P = 0.0039, 0.0039, and 0.0062, respectively) as compared to bland PMMA. Oritavancin-loaded PMMA had higher compressive strength than vancomycin-loaded PMMA on days 3 and 7 (P = 0.0039 and 0.0062, respectively). Compressive elastic moduli were 1226, 1299, and 1394 MPa for bland PMMA; 1253, 1078, and 1245 MPa for oritavancin-loaded PMMA; and 986, 879, and 779 MPa for vancomycin-loaded PMMA on days 0, 3 and 7, respectively. Oritavancin-loaded PMMA had higher compressive elastic moduli than vancomycin-loaded PMMA on days 0 and 7 (P = 0.0250 and 0.0062, respectively). Following polymerization, 1.0% and 51.9% of the initial amount of oritavancin and vancomycin were detected, respectively. C_max, T_max, and AUC_0–24 were 1.7 μg/ml, 2 h, and 11.4 μg/ml for oritavancin and 21.4 μg/ml, 2 h, and 163.9 μg/ml for vancomycin, respectively.

Conclusions

Oritavancin-loaded PMMA had higher compressive strength than vancomycin-loaded PMMA on days 3 and 7 and higher compressive elastic moduli than vancomycin-loaded PMMA on days 0 and 7. However, proportionally less oritavancin than vancomycin eluted out of PMMA.

Two-Stage Exchange Arthroplasty Is a Favorable Treatment Option Upon Diagnosis of a Fungal Periprosthetic Joint Infection

BACKGROUND

This study investigated the prevalence of medical comorbidities, risk factors, and treatment outcomes in patients with fungal periprosthetic joint infection (PJI).

METHODS

All patients with fungal PJI treated from 1999 to 2014 were retrospectively identified at a single institution. Demographic data, comorbidity, and surgical variables were obtained from medical records. Patients were followed up for at least 2 years. PJI was diagnosed using the Musculoskeletal Infection Society criteria. Treatment success was defined using the Delphi consensus criteria. Kaplan-Meier survivorship curves with 95% confidence interval were used for analysis.

RESULTS

Overall, fungal PJIs accounted for 2.4% of the PJI treated at our institution. Twenty-seven patients (93.1%) had 2 or more underlying systemic illnesses. Age and revision surgery were significant risk factors for development of fungal PJI after adjusting for confounding variables. Overall treatment success was 55.2% at 1 year and 40.5% at 5 years. When stratified by initial surgical management, treatment success was 57.1% at 1 year and 28.6% at 5 years following irrigation and debridement; 33.3% at 1 year and 5 years following 1-stage revision; and 57.9% at 1 year and 46.3% at 5 years for 2-stage exchange arthroplasty.

CONCLUSION

Patients with fungal PJI have a high prevalence of systemic illness and poor outcome after surgical management. Irrigation and debridement and single-stage revision demonstrate poor longterm outcomes and may have no place as treatment choices for fungal PJI. Moving forward, our efforts should concentrate on optimizing the systemic status of these patients prior to 2-stage exchange arthroplasty.

Econazole-releasing porous space maintainers for fungal periprosthetic joint infection

While antibiotic-eluting polymethylmethacrylate space maintainers have shown efficacy in the treatment of bacterial periprosthetic joint infection and osteomyelitis, antifungal-eluting space maintainers are associated with greater limitations for treatment of fungal musculoskeletal infections including limited elution concentration and duration. In this study, we have designed a porous econazole-eluting space maintainer capable of greater inhibition of fungal growth than traditional solid space maintainers. The eluted econazole demonstrated bioactivity in a concentration-dependent manner against the most common species responsible for fungal periprosthetic joint infection as well as staphylococci. Lastly, these porous space maintainers retain compressive mechanical properties appropriate to maintain space before definitive repair of the joint or bony defect.

Fungal Musculoskeletal Infections

Fungi are rare but important causes of osteoarticular infections, and can be caused by a wide array of yeasts and molds. Symptoms are often subacute and mimic those of other more common causes of osteoarticular infection, which can lead to substantial delays in treatment. A high index of suspicion is required to establish the diagnosis. The severity of infection depends on the inherent pathogenicity of the fungi, the immune status of the host, the anatomic location of the infection, and whether the infection involves a foreign body. Treatment often involves a combination of surgical debridement and prolonged antifungal therapy.

Elution of High Dose Amphotericin B Deoxycholate From Polymethylmethacrylate

Fungal periprosthetic joint infections are rare, devastating complications of arthroplasty. There is conflicting evidence as to the efficacy of amphotericin B elution from cement spacers. The purpose of this study was to determine whether concentrations of amphotericin B released from bone cement over time would be efficacious in treating a periprosthetic infection. A continuous flow chamber was used to evaluate the in vitro release of amphotericin from cement beads containing 7.5% amphotericin. Following polymerization, 3.3% of the initially loaded amphotericin B was detected. The peak mean concentration eluted from the bone cement was 0.33 μg/mL at 8 hours. The AUC0-24 was 2.79 μg/mL/h; 0.20% of the amphotericin B was released. In conclusion, amphotericin B is released from bone cement at a clinically useful concentration.

In vitro activity of calcium sulfate and hydroxyapatite antifungal disks loaded with amphotericin B or voriconazole in consideration for adjunctive osteomyelitis management

BACKGROUND

Regarding antibiotic-loaded cements, there is an abundant amount of literature regarding the antibacterial in vitro inhibitory and clinical applications for the treatment of osteomyelitis. The opposite can be said about literature regarding in vitro antifungal-loaded cement drug delivery for the treatment of fungal osteomyelitis.

METHODS

Aspergillus fumigatus and Candida (ATCC 1023ATCC, Manassas, Virginia) were plated on antibiotic/antifungal-free plates. Voriconazole- and amphotericin B-impregnated calcium sulfate and hydroxyapatite (HA) disks, calcium sulfate + HA control disks, and control polymethylmethacrylate disks were laid separately onto plates separately inoculated with Aspergillus and Candida spp. The zones of inhibition obtained were measured in millimeters at 24, 36, and 96 hours.

RESULTS

Etest (bioMérieux, Marcy l'Etoile, France) results demonstrated susceptibility of Aspergillus and Candida to amphotericin B and voriconazole. The zone of inhibition data demonstrated that voriconazole and amphotericin B retained their antifungal activity when mixed into the calcium sulfate + HA bone void filler and eluted at biologically effective antifungal concentrations over 96 hours.

CONCLUSIONS

The calcium sulfate + HA bone void filler is a biocompatible ceramic carrier vehicle that can successfully deliver the antifungal drugs voriconazole and amphotericin B in the adjunctive treatment of fungal osteomyelitis. It is a reliable strategy in the local delivery of antifungal drugs to an area of osteomyelitis.

STUDY OF THE DIFFERENT RELEASE CHARACTERISTICS OF ANTIBIOTICS FROM PATIENTS: A DYNAMIC ELUTING SYSTEM TO INVESTIGATE DRUG RELEASE FROM ANTIBIOTIC-IMPREGNATED CALCIUM SULFATE DELIVERY

Background: Antibiotic-impregnated calcium sulfate delivery systems (ACDS) are commonly used to treat chronic osteomyelitis. Our research is to investigate drug release in vitro over a longer period, as a cautious predictor of in vivo release. Methods: The local release behavior of antibiotic in vitro was simulated. The consecutive dynamic eluting experiment was performed based on the pro-operative characteristic of osteomyelitis patients and the determined results of drug concentration in the human drainage tissue fluid (DTF). The concentration of each drug in the receiving solution was detected by ultra-performance liquid chromatography-tandem quadrupole detector mass spectrometry. The ACDS was reviewed by scanning electronic microscopy (SEM) after 48 h, and prepared to be eluted for another examination after 33 days. The mechanism of antibiotic release was analyzed by using the Ritger–Peppas and Weibull equations. Results: The cumulative release rate of vancomycin in a vancomycin-calcium sulfate delivery system (VCDS) was 77.50 % (3.0 mm diameter) and 72.43 % (4.8 mm diameter), while that of the tobramycin in a tobramycin-calcium sulfate delivery system (TCDS) was 88.0 % (3.0 mm diameter) and 84.55 % (4.8 mm diameter). At the 15th day, approximately 27.92% of vancomycin was and 29.35% of tobramycin was released from the local implant in vivo. Using SEM, numerous vancomycin and tobramycin particles were found to be attached to the columnar calcium sulfate crystals at the start of the experiment. The release behavior of the two antibiotics followed a combination of Fickian diffusion and Case II transport mechanisms within the first 48 h, and a Fickian diffusion mechanism during the subsequent time period. The correlation coefficient of tobramycin and vancomycin in vivo and in vitro was 0.9704–0.9949 and 0.9549–0.9782, respectively. Conclusion: A good correlation of the in vivo and in vitro cumulative release rates was observed by comparing the cumulative release rate of drugs in vitro by means of the dynamic eluting model, and in the DTF. Therefore, our study has proved that it is possible to use the dynamic eluting model as a cautious predictor of in vivo release.

In vitro toxicity and activity of Dakin's solution, mafenide acetate, and amphotericin B on filamentous fungi and human cells

OBJECTIVES

Posttraumatic invasive fungal infections threaten critically injured combat-related injuries and require a combination of extensive surgery and systemic antifungal therapy, along with topical antimicrobials used adjunctively to control the infection. We evaluated the in vitro activity of topical agents in varying combinations and concentrations against molds from patients that were responsible for wound invasive fungal infections and the topical agents' toxicity to human cells.

METHODS

Mafenide acetate solutions (2.5%, 5%, and 7.5%), amphotericin B solutions (2 µg/mL, 2 mg/mL, and 20 mg/mL), SMAT (5% mafenide acetate in combination with 2 µg/mL, 2 mg/mL, and 20 mg/mL amphotericin B), and Dakin's solutions (buffered sodium hypochlorite) (0.5%, 0.25%, and 0.125% and 10-fold serial dilutions of 0.25%-0.00000025%) were evaluated for antifungal activity against 4 molds using a time-kill assay using standard conidial suspensions of 5 × 10(4) colony-forming units per milliliter. To assess cellular toxicity, confluent monolayers of human keratinocytes, dermal fibroblasts, and osteoblasts were exposed to these topical agents. Based upon efficacy and toxicity ratios, an additional 10 molds were screened with selected concentrations of the topical agents for antifungal activity and toxicity.

RESULTS

All the topical agents seemed to have a dose-dependent killing with only mafenide acetate showing time killing associated with prolonged contact. There was overall evidence of dose-dependent cytotoxicity of the various topical agents against the various cell lines tested, but there did not seem to be increased cell death with continued exposure to the agents over time. Dakin's solution exhibited dose-dependent toxicity and efficacy with 0.00025% appearing to optimize those parameters.

CONCLUSIONS

Mafenide acetate and amphotericin B did not seem to persistently meet the toxicity and efficacy balance as consistently as Dakin's solution.

Successful treatment of Candida albicans-infected total hip prosthesis with staged procedure using an antifungal-loaded cement spacer

We present a rare case of an immunocompetent host who developed a Candida albicans-infected total hip prosthesis. The infection could not be eradicated with debridement and extensive antifungal therapy. Our patient first underwent a resection of the proximal femur and local treatment with gentamicin-loaded cement beads. In a second procedure, a handmade cement spacer impregnated with voriconazole, amphotericin B, and vancomycin was placed. After 3 months of additional systemic antibiotic therapy, the patient remained afebrile, and a tumor prosthesis was placed. Six years postoperatively, she is doing well, walking with a small limp and no signs of recurrent infection. This is the first report on elution of voriconazole and amphotericin B from bone cement delivered at clinically significant concentrations for at least 72 hours.

Voriconazole is delivered from antifungal-loaded bone cement

BACKGROUND

Local delivery of antifungals is an important modality in managing orthopaedic fungal infection. Voriconazole is a powder antifungal suitable for addition to bone cement that is released from bone cement but the mechanical properties of antimicrobial-loaded bone cement (ALBC) made with voriconazole are unknown.

QUESTIONS/PURPOSES

(1) Is voriconazole release dose-dependent? (2) Is released voriconazole active? (3) Is the loss of ALBC's compressive strength caused by voriconazole dose- and elution-dependent?

METHODS

Sixty standard test cylinders were fabricated with ALBC: 300 or 600 mg voriconazole per batch eluted for 30 days in deionized water. Voriconizole concentration in the eluate was measured using high-performance liquid chromatography. Cumulative-released voriconizole was calculated. Biologic activity was tested. Compressive strength was measured before and after elution. The effect of dose and time on release and compressive strength were analyzed using repeated-measure analysis of variance.

RESULTS

Fifty-seven percent and 63% of the loaded voriconazole were released by Day 30 for the 300-mg and 600-mg formulations, respectively. The released voriconazole was active on bioassay. Compressive strength was reduced from 79 MPa to 53 MPa and 69 MPa to 31 MPa by 30 days for the 300-mg and 600-mg formulations, respectively.

CONCLUSIONS

Voriconazole release from ALBC increases with dose and is bioactive. Loss in compressive strength is greater after elution and with higher dose.

CLINICAL RELEVANCE

Three hundred milligrams of voriconazole in ALBC would be expected to deliver meaningful amounts of active drug in vivo. The compressive strength of ALBC with 600 mg voriconazole is less than expected compared to commonly used antibacterials.