Novel rat tail discitis model using bioluminescentStaphylococcus aureus

Abstract

Management of spondylodiscitis is a challenging clinical problem requiring medical and surgical treatment strategies. The purpose of this study was to establish a rat model of spondylodiscitis that utilizes bioluminescent Staphylococcus aureus, thus permitting in-vivo surveillance of infection intensity. Inocula of the bioluminescent S. aureus strain XEN36 were created in concentrations of 102 CFU/0.1 mL, 104 CFU/0.1 mL, and 106 CFU/0.1 mL. Three groups of rats were injected with the bacteria in the most proximal intervertebral tail segment. The third most proximal tail segment was injected with saline as a control. Bioluminescence was measured at baseline, 3 days, and weekly for a total of 6 weeks. Detected bioluminescence for each group peaked at day three and returned to baseline at 21 days. The average intensity was highest for the experimental group injected with the most concentrated bacterial solution (106 CFU/0.1 mL). Radiographic analysis revealed loss of intervertebral disc space and evidence of osseous bridging. Saline injected spaces exhibited no decrease in intervertebral spacing as compared to distal sites. Histologic analysis revealed neutrophilic infiltrates, destruction of the annulus fibrosus and nucleus pulposus, destruction of vertebral endplates, and osseous bridging. Saline injected discs exhibited preserved annulus fibrosus and nucleus pulposus on histology. This study demonstrates that injection of bioluminescent S. aureus into the intervertebral disc of a rat tail is a viable animal model for spondylodiscitis research. This model allows for real-time, in-vivo quantification of infection intensity, which may decrease the number of animals required for infection studies of the intervertebral disc.

Sensing Living Bacteria in Vivo Using d-Alanine-Derived 11C Radiotracers

“…The rats were injected in the third intervertebral space from the base of the tail at 50% depth (based on the diameter of the tail) as described previously. 50 The infections were allowed to develop for 14 days. At different daily intervals, the rats were injected with a radiotracer and imaged according to the same protocol.…”

Cellular and extracellular matrix of bone, with principles of synthesis and dependency of mineral deposition on cell membrane transport

“…In bone repair, MSCs accumulate and differentiate into fibrocartilage locally and then that cartilage is replaced by bone. This is an important concept: even bone forming in the context of inflammatory signals proceeds through growth of cartilage that is then transformed into bone (10).…”

Preclinical models of vertebral osteomyelitis and associated infections: Current models and recommendations for study design

“…In the model of isolated discitis, radiographic analysis revealed reduced IVD height, evidence of osteophyte formation and discitis, while destruction of the IVD and vertebral endplates was observed histologically. 34 A significant osseous infection was confirmed in implant-inoculated model with localized tissue destruction and loss of bone; soft tissue was filled with young granulation tissue characterized by infiltration of inflammatory cells.…”

“…33-35 10 2 -10 6 CFU of S. aureus was used as an inoculating agent in infectious models. 33,34,36 Titanium screws inoculated with S. aureus have been used to reproduce an implant associated infection to investigate the efficacy of antibiotic therapies. 33,36 In the study of pin tract bacterial migration, skin flora colonized the titanium pins in the external fixation model.…”