Biofilm Producing Staphylococcus epidermidis (RP62A Strain) Inhibits Osseous Integration Without Osteolysis and Histopathology in a Murine Septic Implant Model

• DOI: 10.1002/jor.24512
• Publication Date: 2019-11-06T11:03:35Z
• Authors: Takuya Tomizawa; Masahiro Ishikawa; Sheila N. Bello‐I...; Karen L. de Mesy ...; Hiromu Ito; Stephen L. Kates; John L. Daiss; Christopher Beck; Shuichi Matsuda; Edward M. Schwarz; Kohei Nishitani
• Keywords: Osteolysis; Ex vivo

Despite its presence in orthopaedic infections, Staphylococcus epidermidis's ability to directly induce inflammation and bone destruction is unknown. Thus, we compared a clinical strain of methicillin-resistant biofilm-producing S. epidermidis (RP62A) highly virulent osteolytic aureus (USA300) an established murine implant-associated osteomyelitis model. Bacterial burden was assessed by colony forming units (CFUs), tissue damage histology micro-computed tomography, biofilm scanning electron microscopy (SEM), host gene expression quantitative polymerase chain reaction, osseous integration via biomechanical push-out test. While CFUs were recovered from RP62A-contaminated implants surrounding tissues after 14 days, the bacterial significantly less than USA300-infected tibiae (p < 0.001). In addition, RP62A failed produce any gross pathologies induced USA300 (osteolysis, reactive formation, abscess communities, marrow necrosis, biofilm). However, fibrous present at implant-host interface, rigorous SEM confirmed rare cocci on implants. Gene studies revealed that IL-1β, IL-6, RANKL, TLR-2 mRNA levels RP62A-infected increased versus Sterile controls. Ex vivo testing showed required force with group (7.5 ± 3.4 vs. 17.3 4.1 N; p 0.001), but 10-fold greater (0.7 0.3 Taken together, these findings demonstrate commensal pathogen whose mechanisms inhibit are limited minimal formation implant, low-grade inflammation. © 2019 Orthopaedic Research Society. Published Wiley Periodicals, Inc. J Orthop Res 38:852-860, 2020.