The Open Microbiology Journal

ISSN: 1874-2858 ― Volume 13, 2019

First Detection of Chlamydia trachomatis 'Swedish' Variant (nvCT) in a Russian Couple with Infertility

Valentina Feodorova1, *, Edgar Sultanakhmedov2, Yury Saltykov1, Sergey Zaitsev1, Sergey Utz2, Michael Corbel3, Charlotte Gaydos4, Thomas Quinn4, 5, Vladimir Motin6, *
1 Laboratory for Molecular Biology and NanoBiotechnology, Federal Research Center for Virology and Microbiology, Branch in Saratov, Ap. 6, the 53rd Strelkovoi Divisii Street, Saratov, 410028, Russia
2 Department for Skin Diseases, Saratov State Medical University, 22, Proviantskaya Street, Saratov, 410028, Russia
3 Department of Bacteriology, The National Institute for Biological Standards and Control (NIBSC), Potters Bar, EN6 3QG, UK
4 Division of Infectious Diseases, Johns Hopkins University School of Medicine, 855 N. Wolfe Street, Rangos Bldg, Suite 530, Baltimore, MD21205, USA
5 Division of Intramural Research, National Institute of Allergy and Infectious Diseases, Baltimore, MD, 21205, USA
6 Department of Pathology & Immunology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0609, USA



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.


The study aimed to investigate whether nvCT may be a possible cause of infertility in a couple undergoing in vitro fertilization (IVF).


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.


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.


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.

Keywords: Chlamydia trachomatis, Novel Swedish strain, Co-infection, Extra-genital site, Infertility, Detection methods.

Article Information

Identifiers and Pagination:

Year: 2018
Volume: 12
First Page: 343
Last Page: 352
Publisher Id: TOMICROJ-12-343
DOI: 10.2174/1874285801812010343

Article History:

Received Date: 14/7/2018
Revision Received Date: 23/9/2018
Acceptance Date: 27/9/2018
Electronic publication date: 18/10/2018
Collection year: 2018

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© 2018 Feodorova et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Laboratory for Molecular Biology and NanoBiotechnology, Federal Research Center for Virology and Microbiology, Branch in Saratov, Ap. 6, the 53rd Strelkovoi Divisii Street, Saratov, 410028, Russia; Department of Pathology & Immunology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0609, USA; Tel: 9053850120; E-mail:,


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