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L’évaluation non destructive de l’intégrité structurale des revêtements a une grande importance, parce qu’elle caractérise le comportement et la durabilité de la pointe pour outil de coupe. Dans cet article, nous proposons une méthode d’évaluation par émission acoustique de la qualité de plaquettes en WC-Co (1 × 1 cm) avec une couche mince (8 μm) surfacique en nitrure de titane (TiN) et nitrure de carbone (CN) appliquée par la technique PVD. Les plaquettes avec et sans défauts ont été soumises à des chocs thermiques et leur réponse dynamique a été étudiée par émission acoustique. La réponse donnée par les plaquettes présentant un revêtement efficace et celle donnée par contre par les plaquettes avec différents niveaux d’imperfection peuvent être utilisées comme un premier tentative pour distinguer d’une façon semi-quantitative la qualité du revêtement même. Les résultats obtenus ont été confirmés par observation avec microscope à balayage électronique (MEB).

ABSTRACTThe incidence of infections related to cardiac devices (such as permanent pacemakers) has been increasing out of proportion to implantation rates. As management of device infections typically requires explantation of the device, optimal prophylactic strategies are needed. Cefazolin and vancomycin are widely used as single agents for surgical prophylaxis against cardiac device-related infections. However, combination antibiotic prophylaxis may further reduce infectious complications. To model a localized subcutaneous implant-related infection, a bioluminescent strain of Staphylococcus epidermidiswas inoculated onto a medical-procedure-grade titanium disc, which was placed into a subcutaneous pocket in the backs of mice. In vivobioluminescence imaging, quantification of ex vivoCFU from the capsules and implants, variable-pressure scanning electron microscopy (VP-SEM), and neutrophil enhanced green fluorescent protein (EGFP) fluorescence in LysEGFP mice were employed to monitor the infection. This model was used to evaluate the efficacies of low- and high-dose cefazolin (50 and 200 mg/kg of body weight) and vancomycin (10 and 110 mg/kg) intravenous prophylaxis with or without rifampin (25 mg/kg). High-dose cefazolin and high-dose vancomycin treatment resulted in almost complete bacterial clearance, whereas both low-dose cefazolin and low-dose vancomycin reduced the in vivoand ex vivobacterial burden only moderately. The addition of rifampin to low-dose cefazolin and vancomycin was highly effective in further reducing the CFU harvested from the implants. However, vancomycin-rifampin was more effective than cefazolin-rifampin in further reducing the CFU harvested from the surrounding tissue capsules. Future studies in humans will be required to determine whether the addition of rifampin has improved efficacy in preventing device-related infections in clinical practice.

ABSTRACTVancomycin is widely used for intravenous prophylaxis against surgical implant infections. However, it is unclear whether alternative antibiotics used to treat methicillin-resistant Staphylococcus aureus(MRSA) infections are effective as prophylactic agents. The aim of this study was to compare the efficacies of vancomycin, daptomycin, and tigecycline as prophylactic therapy against a methicillin-sensitive S. aureus(MSSA) or MRSA surgical implant infection in mice. MSSA or MRSA was inoculated into the knee joints of mice in the presence of a surgically placed medical-grade metallic implant. The efficacies of low- versus high-dose vancomycin (10 versus 110 mg/kg), daptomycin (1 versus 10 mg/kg), and tigecycline (1 versus 10 mg/kg) intravenous prophylaxis were compared using in vivobioluminescence imaging, ex vivobacterial counts, and biofilm formation. High-dose vancomycin, daptomycin, and tigecycline resulted in similar reductions in bacterial burden and biofilm formation. In contrast, low-dose daptomycin and tigecycline were more effective than low-dose vancomycin against the implant infection. In this mouse model of surgical implant MSSA or MRSA infection, daptomycin and tigecycline prophylaxis were effective over a broader dosage range than vancomycin. Future studies in humans will be required to determine whether these broader effective dose ranges for daptomycin and tigecycline in mice translate to improved efficacy in preventing surgical implant infections in clinical practice.