A Preliminary Protocol for Induction of Tuberculosis Spondylitis by Mycobacterium Tuberculosis Strain H37R: In-vivo New Zealand White Rrabbits Model

Background: Proper animal model is a critical prerequisite of any experimental study, while it is a lack for tuberculosis spondylitis. This study aimed to validate a protocol for induction of tuberculosis spondylitis in an animal model. Methods: Ten New Zealand white rabbits were used and divided randomly into four experimental groups (n = 8), with 2 rabbits in each group, and the control group (n = 2). A 0.2 mL suspension of 108 CFU/mL H37Rv strain M. tuberculosis was delivered into the drilled hole with a depth of 6-10 mm at the midpoint of the 12th thoracal corpus compared with the saline in the control group. Evaluation of imaging examination by using plain X-ray was done within the targeted time followed by euthanasia protocol. Results: A survival rate of 100% was observed in the present study with all rabbits having stable vital signs during the incubation period. Group 3 with an incubation period of 6 weeks showed the highest success rate for inoculation of M. tuberculosis bacteria in which 7 samples were positive. This was followed by group 2 (75%, incubation 4 weeks), group 1 (37.5%, incubation 2 weeks), and group 4 (12.5%, incubation 8 weeks). The high positive rates were also reported by using culture and PCR staining, 62.5% and 75%, respectively. A slight destruction of the vertebral body was observed in both groups 2 and 3 starting at 4 weeks, postoperatively. Histopathology specimen exhibited an infiltration of numerous inflammatory cells. Conclusions: Establishment of spondylitis tuberculosis model by using New Zealand white rabbit could be successfully formed through 0.2 mL suspension of 108 CFU/mL M. tuberculosis strain H37Rv with a direct inoculation method towards the midpoint of the 12th thoracal vertebral body. In addition, this model showed a high positive rate with a 100% survival rate in both control and 4 treatment groups.