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Contaminated fingers: a potential cause of Chlamydia trachomatis-positive urine specimens
  1. Philip M Giffard1,2,
  2. Rachael A Lilliebridge1,
  3. Judith Wilson1,
  4. Gerald Murray3,4,
  5. Samuel Phillips3,4,
  6. Sepehr N Tabrizi3,4,5,6,
  7. Suzanne M Garland3,4,5,6,
  8. Louise Martin7,
  9. Gurmeet Singh7,8,9,10,
  10. Steven Y C Tong1,11,
  11. Deborah C Holt1,2,
  12. Patiyan Andersson1
  1. 1 Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
  2. 2 School of Psychological and Clinical Sciences, Charles Darwin University, Darwin, Northern Territory, Australia
  3. 3 Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
  4. 4 Department of Microbiology and Infectious Diseases, The Royal Women’s Hospital, Melbourne, Victoria, Australia
  5. 5 Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia
  6. 6 Department of Microbiology, Royal Children’s Hospital, Melbourne, Victoria, Australia
  7. 7 Royal Darwin Hospital, Top End Health Service, Northern Territory Government, Darwin, Northern Territory, Australia
  8. 8 Sexual Assault Referral Centre, Northern Territory Government, Northern Territory, Australia
  9. 9 Northern Territory Medical Program, Flinders University, Darwin, Northern Territory, Australia
  10. 10 Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
  11. 11 Victorian Infectious Disease Service, The Royal Melbourne Hospital, and The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
  1. Correspondence to Dr Philip M Giffard, Global and Tropical Health, Menzies School of Health Research, Royal Darwin Hospital Campus, PO Box 41096, Casuarina, Darwin, Northern Territory, Australia; phil.giffard{at}menzies.edu.au

Abstract

Objectives The detection of an STI agent in a urogenital tract (UGT) specimen from a young child is regarded as being indicative of sexual abuse. However, the probabilities of contamination events that could conceivably lead to STI positive specimens in the absence of sexual contact are unclear. The objective was to estimate the potential for fingers that have come in contact with Chlamydia trachomatis-positive urine to detectably contaminate C. trachomatis-negative urine.

Methods The study design was based on self-experimentation. Dilutions of C. trachomatis elementary bodies (EBs) were prepared. A participant contacted an EB dilution then a urine surrogate specimen. The experiment was performed by three participants using three C. trachomatis isolates, of genotype E, F and B. Two surrogate urine contact methods were used to mimic contamination of a carer assisting with a child’s urine collection. All EB dilutions and urine surrogate specimens were subjected to C. trachomatis assay and quantification in a real-time PCR-based diagnostic system.

Results The amplimer crossing point (Cq) for EB dilutions was 10.0±1.6 less than for corresponding finger contacted urine specimens, which corresponds to ~10 µL of EB suspension transferred. This was largely independent of participant identity, C. trachomatis strain or EB dilution. Hand decontamination led to large reductions in EBs transferred, but transfer remained consistently detectable. Recent Cq data from C. trachomatis-positive clinical urine specimens were collated, and 20% clearly contained sufficient C. trachomatis to detectably contaminate another specimen by finger-mediated transfer, as in this experiment.

Conclusions This study directly demonstrated the potential for urine contaminated fingers to convert a C. trachomatis-negative urine specimen to C. trachomatis positive as a result of contact. Accordingly, procedures for urine specimen collection, particularly from children, need to be designed to prevent contamination.

  • chlamydia trachomatis
  • urine
  • children
  • sexual abuse

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Footnotes

  • Contributors PMG: Contributed to study conception, contributed to study design and formulation of detailed experimental procedure, carried out practical work, analysed data, wrote manuscript. RAL: Contributed to study design, contributed to study design and formulation of detailed experimental procedure, carried out practical work, analysed data. JW: Contributed to formulating detailed experimental procedure, carried out practical work,analysed data, commented on manuscript. GM: Carried out practical work, analysed data, commented on manuscript. SP: Carried out practical work, analysed data, commented on manuscript. SNT: Contributed to study conception, contributed to study design, provided clinical data. SMG: Contributed to study conception, contributed to study design, commented on manuscript. LM: Identified problem that this study addressed, contributed to study design, commented on manuscript. GS: Contributed to study design, commented on manuscript. SYCT: Contributed to study conception, contributed to study design, commented on manuscript. DCH: Contributed to study design and formulation of detailed experimental procedure, carried out practical work, analysed data, commented on manuscript. PA: Contributed to study conception, contributed to study design and formulation of detailed experimental procedure, carried out practical work, analysed data, commented on manuscript.

  • Funding This study was funded by Australian National Health and Medical Research Council project grant 1060768. SYCT was supported by an Australian National Health and Medical Research Council Career Development Fellowship 1065736.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval This study was approved by the Human Research Ethics Committee of the Northern Territory Department of Health and the Menzies School of Health Research, under ethical clearance number 2011-1673.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement All data are included in the publication itself.

  • Correction notice This paper has been amended since it was published Online First. Owing to a scripting error, some of the publisher names in the references were replaced with ’BMJ Publishing Group'. This only affected the full text version, not the PDF. We have since corrected these errors and the correct publishers have been inserted into the references.

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