title: Re-evaluating the sensitivity of the rabbit infectivity test for Treponema pallidum in modern era.
abstract: BACKGROUND
  The rabbit infectivity test (RIT) was previously described as a highly-sensitive method for clinically detecting Treponema pallidum. But our primary study indicated this result may have changed in current antibiotics era.
  
  
  METHODS
  By inoculating rabbits testis with cerebrospinal fluid (CSF) (n=63) and exudate from hard chancre lesions (n=13), we re-evaluated the sensitivity of RIT in modern era. All isolated T. pallidum strains from the RIT were performed for the strain type based on "CDC subtype/tp0548" method. Chi-square and Fisher's exact tests were used to determine the statistical significance of differences across data sets.
  
  
  RESULTS
  Result indicated that 2 of 63 CSF (2/63, 3.17%) and 5 of 13 lesion exudate samples (5/13, 38.47%) were positive in the RIT, with a much longer time to detection for CSF samples. Only 1 of 28 samples from patients who admitted treatment with antibiotics prior to clinical exam was positive in the RIT; while 6 of 48 patients, who admitted no recent exposure to antibiotics or was unclear about the medical history, were positive in RIT. DNA sequence analysis revealed 6 strains of 14d/f subtype and one strain of 14a/f subtype.
  
  
  CONCLUSIONS
  In conclusions, RIT is no longer a highly sensitive method for detecting T. pallidum in clinical samples as before, and is not inadequately considered to be a reference method for measuring the sensitivity of other new methods, such as the PCR. These data represent the first reexamination of the sensitivity of RIT in the post-antibiotic era with a large clinical sample.
authors.affiliation: Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen 361004, China.
authors.forename: Man-Li
authors.initials: ML
authors.lastname: Tong
authors.affiliation: Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen 361004, China.
authors.forename: Hui-Lin
authors.initials: HL
authors.lastname: Zhang
authors.affiliation: Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen 361004, China.
authors.forename: Xiao-Zhen
authors.initials: XZ
authors.lastname: Zhu
authors.affiliation: Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen 361004, China.
authors.forename: Jin-Yi
authors.initials: JY
authors.lastname: Fan
authors.affiliation: Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen 361004, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Gao
authors.affiliation: Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen 361004, China.
authors.forename: Li-Rong
authors.initials: LR
authors.lastname: Lin
authors.affiliation: Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen 361004, China.
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Liu
authors.affiliation: Department of Gynaecology and Obstetrics, Xiamen Huli District Maternity and Child Care Hospital, Xiamen 361000, China.
authors.forename: Shu-Lian
authors.initials: SL
authors.lastname: Li
authors.affiliation: Department of Gynaecology and Obstetrics, Xiamen Huli District Maternity and Child Care Hospital, Xiamen 361000, China.
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Lin
authors.affiliation: Department of Gynaecology and Obstetrics, Xiamen Huli District Maternity and Child Care Hospital, Xiamen 361000, China.
authors.forename: Zhi-Feng
authors.initials: ZF
authors.lastname: Lin
authors.affiliation: Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen 361004, China; Department of Hospital Infection and Medical Healthy Care, Xiamen Zhongshan Hospital, Fujian Medical University, Xiamen 361004, China.
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Niu
authors.affiliation: Department of Neurology, Medical College of Xiamen University, Xiamen 361004, China. Electronic address: zwh610547@xmu.edu.cn.
authors.forename: Wei-Hong
authors.initials: WH
authors.lastname: Zheng
authors.affiliation: Clinical Laboratory, Zhongshan Hospital, Medical College of Xiamen University, Xiamen 361004, China. Electronic address: yangtianci@xmu.edu.cn.
authors.forename: Tian-Ci
authors.initials: TC
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D019411:Clinical Laboratory Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D057230:Limit of Detection; D008297:Male; D008875:Middle Aged; D058889:Molecular Typing; D009494:Neurosyphilis / Q000382:microbiology; D011817:Rabbits; D014210:Treponema pallidum / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity*; D055815:Young Adult
keywords: Antibiotic; Rabbit infectivity test; Sensitivity; Syphilis; Treponema pallidum