title: Antibiotic penetration into rabbit nucleus pulposus with discitis.
abstract: OBJECTIVE
  To assess the penetration into nucleus pulposus (NP) of cephazolin and clindamycin in a discitis model.
  
  
  METHODS
  Twenty New Zealand white rabbits were inoculated with 103 Staphylococcus aureus at lumbar disc space. The rabbits with discitis confirmed by MRI 10 days after inoculation were divided into two groups. One was given cephazolin by intravenous (IV) at 80 mg/kg/day at 1.5 h interval for 5 half-lives; the other was given clindamycin by IV at 30 mg/kg/day at 2.5-h interval for 5 half-lives. Thirty minutes after completion of the last dose, NP and serum were sent to measure antibiotic concentration.
  
  
  RESULTS
  Two rabbits died during inoculation. After 10 days, 18 rabbits were confirmed discitis in the inoculated levels. The cephazolin and clindamycin can diffuse throughout the infected, sham-infected and normal NP. The serum concentration of cephazolin and clindamycin was 251.3 ± 40.5 and 21.6 ± 4.71 mg/l, respectively. The cephazolin concentration in infected NP (1.93 ± 0.84 mg/l) was higher than that in sham-infected (1.73 ± 0.61 mg/l) and normal NP (1.68 ± 0.65 mg/l), but the difference showed no statistically significant (P > 0.05). The cephazolin penetration into NP averaged 0.68-0.77 % of serum level. The clindamycin concentration in infected NP (4.32 ± 1.54 mg/l) was higher than that in sham-infected NP (2.63 ± 1.26 mg/l) and normal NP (2.59 ± 1.01 mg/l) (P < 0.05). The penetration into NP averaged 11.9-20 % of serum level. There was no significance difference between sham-infected and normal NP in clindamycin and cephazolin concentration (P > 0.05).
  
  
  CONCLUSIONS
  This study demonstrates cephazolin and clindamycin can penetrate the infected and normal NP. The antibiotics charge influences the delivery. Furthermore, infection condition selectively promotes antibiotic distribution within NP.
authors.affiliation: Department of Orthopedics, Subei People's Hospital of Jiangsu Province, Clinical Medical College of Yangzhou University, 98 Nantong West Road, Yangzhou, 225001, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.forename: Jing-cheng
authors.initials: JC
authors.lastname: Wang
authors.forename: Xin-min
authors.initials: XM
authors.lastname: Feng
authors.forename: Wei-hua
authors.initials: WH
authors.lastname: Cai
authors.forename: Jian-dong
authors.initials: JD
authors.lastname: Yang
authors.forename: Ning
authors.initials: N
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000097:blood / Q000493:pharmacokinetics; D002437:Cefazolin / Q000097:blood / Q000493:pharmacokinetics*; D002981:Clindamycin / Q000097:blood / Q000493:pharmacokinetics*; D015299:Discitis / Q000188:drug therapy* / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D007403:Intervertebral Disc / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D008159:Lumbar Vertebrae; D008279:Magnetic Resonance Imaging; D008297:Male; D011817:Rabbits; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000473:pathology; D013211:Staphylococcus aureus
chemical_list: D000900:Anti-Bacterial Agents; D002981:Clindamycin; D002437:Cefazolin
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