Objectives Most international STI guidelines recommend Chlamydia trachomatis anorectal testing in women after self-reported sexual exposure or symptoms in women. However, it has been shown that the prevalence of anorectal C. trachomatis is as high (7%–17 %) in women who do not report anorectal intercourse (AI) as in women who do. This study assessed the correlation between the genital and anorectal C. trachomatis load in concurrently infected women for increased microbiological insight.
Methods A convenience sample of 105 women with a concurrent (genital and anorectal) C. trachomatis infection was included from the STI clinic in South Limburg, the Netherlands. Women provided self-collected vaginal and anorectal swabs. The C. trachomatis load was quantified with qPCR and the human cell load was assessed to ensure sample adequacy. Genital and anorectal C. trachomatis loads were divided into tertiles for comparison. The χ2 test and linear regression were used to compare genital and anorectal C. trachomatis loads and identify determinants associated with load.
Results The overall median C. trachomatis load was higher in genital (median 5.3 log10 C. trachomatis/ml) than anorectal samples (median 3.4, p ≤ 0.001), but both loads were within the same range. The genital and anal load categories were not related within one woman (p = 0.99), both in women with and without AI. The anorectal C. trachomatis load was in the same or higher load category than the genital load in 56% of women without AI, and 79% of women with AI.
Conclusions Although no cut-off for clinical relevance is known, an anorectal C. trachomatis load in the same or higher load category than the genital C. trachomatis load is likely to be clinically relevant. Other measurements should also be taken into account, such as leucocytes or bacterial viability to distinguish infection from contamination or exposure.
- chlamydia trachomatis
- bacterial load
- female genital disease
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JAMCD and GAFSvL contributed equally.
Handling editor Jackie A Cassell
Contributors CJPAH, PW, NHTMD-M, JAMCD and GAFSvL contributed to the design of the work. JAMCD and GAFSvL partook in the acquisition and analyses of the data for the work. GAFSvL and GAFSvL drafted the work, which was revised critically by PW, NHTMD-M and CJPAH.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Medical Ethical Committee of the University of Maastricht, The Netherlands (METC 11-4-108).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.