Antibiotic penetration into rabbit nucleus pulposus with discitis

Area of Science:

• Pharmacology
• Infectious Diseases
• Spinal Surgery

Background:

• Discitis, an infection of the intervertebral disc, poses treatment challenges due to poor antibiotic penetration.
• Understanding antibiotic distribution in the nucleus pulposus (NP) is crucial for effective treatment strategies.

Purpose of the Study:

• To evaluate the penetration of cephazolin and clindamycin into the nucleus pulposus (NP) in a rabbit model of discitis.
• To compare antibiotic concentrations in infected, sham-infected, and normal NP tissues.

Main Methods:

• Discitis was induced in New Zealand white rabbits using Staphylococcus aureus.
• Antibiotic concentrations in serum and NP were measured after intravenous administration of cephazolin or clindamycin.
• Magnetic Resonance Imaging (MRI) confirmed discitis in inoculated rabbits.

Main Results:

• Both cephazolin and clindamycin penetrated the NP in infected, sham-infected, and normal discs.
• Clindamycin showed significantly higher concentrations in infected NP compared to sham-infected and normal NP (P < 0.05).
• Cephazolin penetration into NP averaged 0.68-0.77% of serum levels, while clindamycin penetration averaged 11.9-20%.

Conclusions:

• Cephazolin and clindamycin effectively penetrate the nucleus pulposus, even in normal discs.
• Antibiotic charge appears to influence drug delivery into the NP.
• The infection process selectively enhances the distribution of antibiotics within the NP.