Introduction: Prosthetic joint infections (PJIs) are difficult to treat and represent a significant burden to the healthcare system. Two-stage revision surgery with placement of an antibiotic-loaded cement spacer is currently the gold standard for treatment in the United States for late-onset infections. We evaluate the efficacy of varying doses of vancomycin added to antibiotic-containing acrylic cement spacers and discuss the biomechanical and antimicrobial properties of using high versus low doses of vancomycin in cement spacers in the hip and knee. Materials and Methods: Commercially available Copal cement containing either gentamicin and clindamycin (G + C) or gentamicin and vancomycin (G + V) was prepared with the manual addition of low (2 g) and high (6 g) doses of vancomycin. In vitro mechanical testing was then carried out according to ISO 5833 and DIN 53435, as well as inhibition zone assays against common PJI pathogens. Additionally, inhibition zone assays were conducted on two commercially available prefabricated spacers containing gentamicin: Copal Exchange G and Cemex Spacer-K. Results: In biomechanical testing, Copal G + V with the addition of 6 g of vancomycin failed to meet the ISO standard. Copal G + C and Copal G + V with low and high dosages of vancomycin were all effective against the tested pathogens and displayed constant efficacy for a duration of 42 days. High doses of vancomycin showed significantly lower mechanical stability. Moreover, Copal Exchange G showed significantly larger inhibition zones across 42 days. Discussion: While higher concentrations of vancomycin appear to improve the antimicrobial efficacy of cement, they also reduce its mechanical stability. Despite its smoother surface, the Copal Exchange G spacer exhibits large inhibition zones after 1 day and maintains consistently large inhibition zones over 6 weeks. Thus, it may be preferred for use in two-stage revision surgery. Conclusion: Copal Exchange G is more effective than Cemex Spacer K against S. aureus and E. coli. The manual addition of vancomycin to cement containing double antibiotics is very effective. The influence on ISO compression is low, the ISO bending modulus is increased, and ISO bending, DIN bending, and DIN impact, are reduced.

Background: There are currently no recommendations to direct the optimal diagnosis and treatment of fungal osteoarticular infections, including prosthetic joint infections and osteomyelitis. Active agents (fluconazole; amphotericin B) are regularly applied per os or intravenously. Other drugs such as voriconazole are used less frequently, especially locally. Voriconazole is less toxic and has promising results. Local antifungal medication during primary surgical treatment has been investigated by implanting an impregnated PMMA cement spacer using intra-articular powder or by daily intra-articular lavage. The admixed dosages are rarely based on characteristic values and microbiological and mechanical data. The purpose of this in vitro study is to investigate the mechanical stability and efficacy of antifungal-admixed PMMA with admixed voriconazole at low and high concentrations. Methods: Mechanical properties (ISO 5833 and DIN 53435) as well as efficacy with inhibition zone tests with two Candida spp. were investigated. We tested three separate cement bodies at each measuring time (n = 3) Results: Mixing high dosages of voriconazole causes white specks on inhomogeneous cement surfaces. ISO compression, ISO bending, and DIN impact were significantly reduced, and ISO bending modulus increased. There was a high efficacy against C. albicans with low and high voriconazole concentrations. Against C. glabrata, a high concentration of voriconazole was significantly more efficient than a dose at a low concentration. Conclusions: Mixing voriconazole powder with PMMA (Polymethylmethacrylate) powder homogeneously is not easy because of the high amount of dry voriconazole in the powder formulation. Adding voriconazole (a powder for infusion solutions) has a high impact on its mechanical properties. Efficacy is already good at low concentrations.

(1) Background: The addition of antibiotics to bone cements is a common practice in the treatment of periprosthetic joint infections. In revision cases, the amount and type of antibiotic is often insufficient and additional antibiotics must be added. The addition, however, changes the product itself, and the surgeon becomes the “manufacturer” of the bone cement. PMMAe wished to clarify whether the admixture of antibiotics changes the mechanical stability of the bone cements used and if the added antibiotics were still functional and released in sufficient quantities. (2) Methods: We compared two industrially manufactured vancomycin-containing PMMA cements; the low-viscous VancogenX^® (TECRES, Sommacampagna, Italy) and the high-viscous Copal^® G+V (Heraeus Medical GmbH, Wehrheim, Germany), with two PMMA cements loaded with aminoglycosides, to which 2.0 g of vancomycin (Hexal CT1631) were manually added—the high-viscous Smartset^® GHV and the medium-viscous Antibiotic Simplex with Tobramycin (antibiotic Simplex^® T). Test specimens of the bone cements were used to determine mechanical stability (bending strength and bending module), and the release of the antibiotics was determined by HLPC and modified Kirby–Bauer assays. (3) Results: All tested bone cements showed an initial high release within the first hours. Repeated testing after 24 h showed a reduced efficacy of VancogenX^® and Smartset^® GHV in Kirby–Bauer assays. Long-time release over days showed a release of functional antimicrobial active ingredients over this period of time in anti-microbial assays, but no activity of VancogenX^® from day 21 onward. No significant differences in the ISO bending modules could be detected, but in contrast to the bending module, the ISO bending strength was substantially reduced by 10–15 mPal in comparison to both cements of the reference group. The Simplex^®T met just the ISO 5833; the Smartset^® GHV did not after adding vancomycin. (4) Conclusions: In conclusion, the manual addition of 2 g of vancomycin to 40 g of PMMA powder is recommended for the treatment of methicillin-resistant staphylococci. Vancomycin is released over a period of 42 days with concentrations above the MIC for typical staphylococci. The mechanical properties of the PMMA just met, or did not fulfill, ISO mechanical specification. Copal^® G+V showed a better elution than VancogenX^® over time.

Purpose: Antibiotic coating for several medical devices has been carried out; however, there are only few studies about coating hernia meshes with antimicrobial substances. In this study we checked the capacity of different commercially available hernia meshes to act as drug carrier.Methods: The meshes were coated with gentamicin palmitate, chlorhexidine palmitic acid and chlorhexidine palmitate. The coating mass and subsequent in vitro delivery rate were evaluated for gentamicin palmitate by fluorescence polarization. For Chlorhexidine coated devices the coating mass was determined by weighing. The in vitro delivery rate was determined by UV absorption (255 nm). The interaction of each mesh to the different coating substances was observed by scanning electron microscopy.Results: 1. Certain uniformity was observed on the quantity of chlorhexidine coating the surface of each mesh used when compared with gentamicin palmitate coating. 2.We did not detect significant difference between the amounts of gentamicin palmitate released from each mesh. 3. The release of chlorhexidine palmitate and chlorhexidine palmitic acid from UltraPro™ and Mersilene™ were significantly higher (p<0.05) in comparison with the other two meshes. 4. The coating substances covered the surface of the fibers without damaging its structure. 5. The coating substances were distributed all along the fibers in all samples.Conclusions: We suggest the use of chlorhexidine palmitate and chlorhexidine palmitic acid, as well as gentamicin palmitate, for coating of hernia meshes aiming prevention of infections. Further investigation of the bactericidal effect of coated hernia meshes against biofilm form of S. aureus and other device-related infections is suggested.

Antibiotic-loaded bone cements (ALBCs) are used to prevent and treat periprosthetic joint infections (PJI). This study compares the in vitro release and antibacterial effectiveness of gentamicin from Palacos^® R+G and tobramycin from Simplex^® T. Standardized cylindrical specimens of Palacos^® R+G and Simplex^® T were incubated in phosphate-buffered saline. Antibiotic release was quantified using high-performance liquid chromatography (HPLC) over 14 and 42 days. Antibacterial efficacy was assessed using inhibition zone tests (IZT) against Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli over 42 days. Palacos^® R+G exhibited a significantly higher and more sustained antibiotic release of gentamicin compared to tobramycin from Simplex^® T. The cumulative release of gentamicin from Palacos^® R+G was 1.148 µg/cm², while Simplex^® T released 198.87 µg/cm² tobramycin over 14 days. Inhibition zone tests showed that Palacos^® R+G maintained antibacterial activity for 42 days, while Simplex^® T’s activity diminished after 14 days. Statistical analysis confirmed significant differences in antibacterial efficacy between the two cements. Palacos^® R+G demonstrated superior gentamicin release and sustained antibacterial activity compared to tobramycin from Simplex^® T. These findings suggest that Palacos^® R+G may offer better clinical outcomes in preventing and treating PJIs.

(1) Background: There is an ongoing discussion on the elution efficacy of antibiotic-impregnated cements. Our experiments were intended to clarify if there are differences in the antibiotic elution of HPLC compared with inhibition zone testing using eluates or PMMA discs. (2) Materials and Methods: Two cement brands with different concentrations of the active ingredient were tested in antimicrobial Kirby–Bauer (disc diffusion) assays. Cement platelets were directly applied on the agar plates and their zone of inhibition was measured. In parallel, the platelets were incubated in phosphate buffered saline (PBS) and at distinct points of time transferred into new buffer. At these time points, 50 µL of the bone cement eluates was used for zone of inhibition testing. Standard gentamicin sulfate solutions served as a control in the same test setup. To verify the microbiological investigations, the antibiotic content of the eluates was also measured via high-performance liquid chromatography (HPLC). (3) Results: The experiments with cement eluates showed better differentiable results than the direct application of the cement discs. The results were also comparable to investigations with HPLC and gentamicin sulfate standard solutions. (4) Conclusions: The results of elution rates are influenced by the test system and the period of observation chosen. The microbial test systems reflect the results of HPLC to the same degree and give evidence of the efficacy of the antibiotics. The HPLC tests on eluates were more suitable in representing differences in release characteristics.