RT Journal Article SR Electronic T1 Contaminated fingers: a potential cause of Chlamydia trachomatis-positive urine specimens JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP 32 OP 36 DO 10.1136/sextrans-2016-053081 VO 94 IS 1 A1 Philip M Giffard A1 Rachael A Lilliebridge A1 Judith Wilson A1 Gerald Murray A1 Samuel Phillips A1 Sepehr N Tabrizi A1 Suzanne M Garland A1 Louise Martin A1 Gurmeet Singh A1 Steven Y C Tong A1 Deborah C Holt A1 Patiyan Andersson YR 2018 UL http://sti.bmj.com/content/94/1/32.abstract AB 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.