Improvement of laboratory diagnostics of urogenital chlamydial infection in patients with impaired reproductive functions found to be infected with Chlamydia trachomatis

Abstract

The dominant role in human infertility has been attributed to sexually transmitted infections (STIs) with a leading contribution of urogenital chlamydial infection (UGCI) caused by Chlamydia trachomatis (CT). the two variants of this pathogen are represented by the wild-type (wtCT) and new Swedish (nvCT) strains containing 377 bp deletion within the cryptic plasmid orf1 gene. Objective. The purpose of the study was investigation of the clinical specimens obtained from the urogenital tract of couples coping with infertility for the presence of genetic material of wtCT and nvCT. Material and methods. Clinical samples (scrapings from the urethra and cervix) obtained from 25 to 41 years old couples (n = 14) were tested for the presence of identifiable wtCT and nvCT chlamydia DNA by monoplex and duplex PCR, specific antigens C. trachomatis in elementary bodies by using immunofluorescence analysis (IFA), while detection of anti-chlamydia antibodies in sera was determined by immunoenzymatic assay (IEA). Results. The nvCT variant with typical deletion of 377 bp within the orf1 gene that belongs to the genovar e subtype E1 was detected in 100% of couples with infertility. The negative results of DNA testing for wtcT were registered in 87.5% of patients from this group, while one individual (12.5%) was likely coinfected with nvCT and wtCT of E1 and D genovars, respectively. The wtCT strains of genovar E (subtypes E1, E2, E6), g (subtypes G1, G2), F (subtypes F1), and K were identified in control group among patients with UGCI. The study revealed difficulties in detection of nvCT by nucleic acid amplification test (NAAT), IFA, and IEA; data on comparison of the efficacy of these methods are presented. Conclusion. Chronic UGCI in patients with reproductive dysfunctions can be caused by nvCT alone or as result of co-infection with nvCT and wtCT. The negative results in NAAT may not 100% correlate with the absence of UGCI that requires further confirmation in tests allowing detection of all known variants of C. trachomatis.