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713. Preventive Administration of MEDI6389, a Combination of Monoclonal Antibodies (mAbs) Targeting Alpha-Toxin (AT), Panton-Valentine Leukocidin (PVL), Leukocidin ED (LukED), Gamma-Hemolysin and Clumping Factor A (ClfA), in a Rabbit Model of USA300 MRSA Prosthetic Joint Infection (PJI)

BACKGROUND: mAbs targeting staphylococcal virulence factors could represent an interesting preventive strategy in PJI. We evaluate here MEDI6389 compared with isotype-matched control IgG (c-IgG) in a rabbit model of USA300 MRSA PJI. METHODS: Rabbits were randomized for prophylaxis with either c-IgG...

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Detalles Bibliográficos
Autores principales: Yanjie, Mao, Valour, Florent, Vu Vi Tran, Giang, Vu, Trang, Delaye, Thomas, Quynh Nhu Nguyen, Tran, Tkaczyk, Christine, Cheng, Li, Sellman, Bret R, An Diep, Binh
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6810972/
http://dx.doi.org/10.1093/ofid/ofz360.781
Descripción
Sumario:BACKGROUND: mAbs targeting staphylococcal virulence factors could represent an interesting preventive strategy in PJI. We evaluate here MEDI6389 compared with isotype-matched control IgG (c-IgG) in a rabbit model of USA300 MRSA PJI. METHODS: Rabbits were randomized for prophylaxis with either c-IgG (n = 13; 30 mg/kg; controls) or MEDI6389 (n = 13; 30 mg/kg of each mAb) administered intravenously 12h before infection. A cemented screw and ultrahigh-molecular-weight polyethylene washer were placed intraarticularly in the external femoral condyle. After suturing the joint capsule and musculocutaneous layers, 300 µL of a standardized bacterial inoculum containing 5 × 10(5) CFU of a USA300 MRSA clinical isolate were injected intraarticularly. Animals were euthanized on day 8 and the knee joint was harvested for bacteriological analysis (synovial bacterial counts, and enumeration of screw-adherent bacteria after sonication) and histology (conventional pathology, and transmission electron microscopy [TEM] for neutrophils analysis). In vivo observations made on neutrophils were confirmed by TEM analysis of human neutrophils incubated in vitro with purified PVL, LukED, and gamma-hemolysin with or without the corresponding mAb. RESULTS: In comparison with the control group, the average amount of pus (1.7 ± 1.8 vs. 3.1 ± 1.2 g, P = 0.026) and the number of bacteria in the synovial pus (5.9±1.5 vs. 7.2±1.4 log10 CFU, P = 0.031) and on the screw (2.7 ± 1.5 vs. 4.1 ± 1.6 log10 CFU, P = 0.035) were decreased in animals pretreated by MEDI6389. Conventional pathological examination showed a marked reduction in synovitis of MEDI6389-pretreated animals. TEM of synovitis harvested from infected knee joints of control animals showed significant greater number of abnormal neutrophils that appeared rounded, with condensed nucleus and no granules, compared with those pretreated with MEDI6389 (P = 0.002). This classical leukocidin-induced neutrophilic killing phenotype could be neutralized with anti-leukocidin mAbs using ex vivo human neutrophils incubated with PVL, LukED, HlgAB, or HlgCB. CONCLUSION: The preventive administration of MEDI6389 allows a reduction of local inflammation and bacterial burden in this USA300 MRSA rabbit PJI model. [Image: see text] DISCLOSURES: All authors: No reported disclosures.