Abstract
Background:Chronic asymptomatic chlamydial genital infection caused by the wild-type of Chlamydia trachomatis (wtCT) is the most common bacterial infection causing human infertility. The novel ‘Swedish’ variant of С.trachomatis (nvCT) which contains a 377 bp deletion in a region that is specifically targeted in some nucleic acid amplification tests may impede diagnosis.Objective: The study aimed to investigate whether nvCT may be a possible cause of infertility in a couple undergoing in vitro fertilization (IVF).Method:Clinical specimens from both genital (urethra and cervix) and extra-genital sites (pharynx, conjunctive, blood) of a couple who experienced multiple unsuccessful attempts at pregnancy by natural fertilization and IVF procedures were analyzed before and after antibiotic therapy. Both partners had neither somatic nor endocrinal abnormality nor any clinically apparent genital manifestations of Chlamydia or other STIs.Results:Before antibiotic therapy all the samples of the Female Partner (FP) contained DNA of only the nvCT. After antibiotic therapy, additionally, DNA of wtCT of genovars E and D was detected in specimens from her conjunctiva and oropharynx. All samples of the Male Partner (MP) revealed co-infection of nvCT and wtCT. Identical SNP within the variable region 4 (VD4) of the ompA gene confirmed the identity of the wtCT strains found in both partners. The FP had a positive anti-chlamydial IgG titer. The sperm characteristics of the MP, motility (immotile spermatozoa was 51.1% versus 21.6%) and vitality (46% versus 68%) declined progressively, and the MP anti-chlamydial IgG titer was negative.Conclusion:Infertility in this couple may have been caused by chronic asymptomatic and persistent nvCT-associated infection that was complicated by re-infection later with wtCT. This study illustrates the importance of including detection methods for nvCT strains in the investigation of infertility cases.
Highlights
Chlamydia trachomatis is currently one of the most prevalent sexually transmitted pathogens worldwide and a major cause of infertility affecting 10-15% of all couples worldwide [1 - 4]
The initial screening in October 2012 prior to the planned in vitro fertilization (IVF) procedure revealed the lack of С.trachomatis DNA in the genital specimens of both partners using AmpliSens Chlamydia trachomatis-Eph and -FL kits (AmpiSens-Eph and AmpiSens-FL)
Further we tested the samples for the presence of chlamydial DNA in PCR by using primers targeting different parts of the C. trachomatis cryptic plasmid, as well as primers swCT_serE_F/swCT_serE_R (Table 1) flanking the area of deletion identified in the orf1 of the Swedish strains
Summary
Chlamydia trachomatis is currently one of the most prevalent sexually transmitted pathogens worldwide and a major cause of infertility affecting 10-15% of all couples worldwide [1 - 4]. A number of animal studies present clear evidence that human strains of wtCT are capable of causing infertility [5, 6] This wtCT-associated infection can result in alteration of semen parameters, induction of apoptosis in spermatozoa, and decrease in the reproductive performance of fertile male mice [5]. The actual contribution of chlamydial infection caused by the novel ‘Swedish’ variant of С.trachomatis (nvCT) to couple infertility remains poorly investigated This chlamydial variant, which carries a 377 bp deletion within the cryptic plasmid that has caused false-negative responses in routine nucleic acid amplification tests (NAATs) [10, 11] is a novel challenge for laboratory diagnosis of chlamydial infection worldwide. The novel ‘Swedish’ variant of С.trachomatis (nvCT) which contains a 377 bp deletion in a region that is targeted in some nucleic acid amplification tests may impede diagnosis
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