O20.6 Chlamydia trachomatis viable load at six different anatomical sample sites in women (CHLAMOUR)

Abstract

Background Nucleic acid amplification tests (NAATs) have revolutionized our ability to diagnose Chlamydia trachomatis (CT). Sometimes, in addition, assessment of CT viability would help to gain more insight in the clinical impact of a positive NAAT. Methods to assess the CT viability have become available in research settings (e.g. viability-PCR; V-PCR). Here we assess viability in six different anatomic sites in women. Methods Immediately prior to treatment (STI clinic South Limburg), 28 vaginal NAAT-CT-positive (COBAS4800 CT/NG) adult women, were included in the ‘CHLAMOUR’ study. We used V-PCR to assess CT viable load (log10 CT/ml) in same clinician taken standardized samples from the cervix, vagina, perineum, anus, optional rectum, and pharynx. Mean loads were compared using t-tests. Results Twenty-eight women were included of whom 68% (19/28) consented to proctoscopic examination (rectal). NAAT-CT-positive rate was 75% for cervix, 79% vagina, 64% perineum, 64% anus, 74% rectum, and 21% for pharynx. Viable load was detected in 90% (19/21) CT positive cervix, 77% (17/22) vagina, 11% (2/18) perineum, 61% (11/18) anal, 93% (13/14) rectal, and 0% (0/6) pharynx samples. The mean viable load was marginally higher in cervical compared to vaginal samples (4.37 [SD:1.35] vs. 3.45 [SD:1.05], p=0.055). Mean viable load was higher in rectal compared to anal samples (3.51 [SD:0.51] vs. 2.70 [SD:0.42], p=0.01). Viable load was 2.72 [SD:1.69] CT positive perineum samples. Conclusions The amount of viable CT varied by anatomic site, and were highest ‘upward in the body’, which is thus likely to represent actual site of infection. Still, the vaginal and anal sites (that are usually self-sampled) had high concordance with the cervical and rectal sites. CT at the perineum may indicate autoinoculation. Notably, the presence of viable CT in anorectal samples indicated the presence of an active anorectal infection, which should be accounted for in comprehensive CT management.