Novel in vivo mouse model of implant related spine infection.
Post-operative spine infections are a challenge, as hardware must often be retained to prevent destabilization of the spine, and bacteria form biofilm on implants, rendering them inaccessible to antibiotic therapy, and immune cells. A model of posterior-approach spinal surgery was created in which a stainless steel k-wire was transfixed into the L4 spinous process of 12-week-old C57BL/six mice. Mice were then randomized to receive either one of three concentrations (1 × 102, 1 × 103, and 1 × 104colony forming units (CFU)) of a bioluminescent strain of Staphylococcus aureus or normal saline at surgery. The mice were then longitudinally imaged for bacterial bioluminescence to quantify infection. The 1 × 102CFU group had a decrease in signal down to control levels by POD 25, while the 1 × 103and 1 × 104CFU groups maintained a 10-fold higher signal through POD 35. Bacteria were then harvested from the pin and surrounding tissue for confirmatory CFU counts. All mice in the 1 × 104CFU group experienced wound breakdown, while no mice in the other groups had this complication. Once an optimal bacterial concentration was determined, mice expressing enhanced green fluorescent protein in their myeloid cells (Lys-EGFP) were utilized to contemporaneously quantify bacterial burden, and immune response. Neutrophil fluorescence peaked for both groups on POD 3, and then declined. The infected group continued to have a response above the control group through POD 35. This study, establishes a noninvasive in vivo mouse model of spine implant infection that can quantify bacterial burden and host inflammation longitudinally in real time without requiring animal sacrifice. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:193-199, 2017.
Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California Los Angeles (UCLA), Santa Monica, 90404, California.
Eric M
EM
Dworsky
Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California Los Angeles (UCLA), Santa Monica, 90404, California.
Vishal
V
Hegde
Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California Los Angeles (UCLA), Santa Monica, 90404, California.
Amanda H
AH
Loftin
Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California Los Angeles (UCLA), Santa Monica, 90404, California.
Sherif
S
Richman
Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California Los Angeles (UCLA), Santa Monica, 90404, California.
Yan
Y
Hu
Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California Los Angeles (UCLA), Santa Monica, 90404, California.
Elizabeth
E
Lord
Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California Los Angeles (UCLA), Santa Monica, 90404, California.
Kevin P
KP
Francis
Department of Dermatology, Johns Hopkins School of Medicine, Baltimore, 21231, Maryland.
Lloyd S
LS
Miller
Department of Orthopaedic Surgery, Keck School of Medicine at University of Southern California (USC), Los Angeles, 90017, California.
Jeff C
JC
Wang
Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California Los Angeles (UCLA), Santa Monica, 90404, California.
Anthony
A
Scaduto
Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California Los Angeles (UCLA), Santa Monica, 90404, California.
Nicholas M
NM
Bernthal
D000818:Animals; D004195:Disease Models, Animal; D008163:Luminescent Measurements; D008297:Male; D008810:Mice, Inbred C57BL; D009504:Neutrophils; D016459:Prosthesis-Related Infections; D011897:Random Allocation; D013122:Spinal Diseases; D013211:Staphylococcus aureus
Staphylococcus; bioluminescence; implant infection; spine