When Bacteria and Viruses Collide: A Tale of Chlamydia trachomatis and Sexually Transmitted Viruses

Abstract

The global incidence of sexually transmitted infections (STIs) remains high, with the World Health Organization (WHO) estimating that over 1 million people acquire STIs daily. STIs can lead to infertility, pregnancy complications, and cancers. Co-infections with multiple pathogens are prevalent among individuals with an STI and can lead to heightened infectivity and more severe clinical manifestations. Chlamydia trachomatis (CT) is the most reported bacterial STI worldwide in both men and women, and several studies have demonstrated co-infection of CT with viral and other bacterial STIs. CT is a gram-negative bacterium with a unique biphasic developmental cycle including infectious extracellular elementary bodies (EBs) and metabolically active intracellular reticulate bodies (RBs). The intracellular form of this organism, RBs, has evolved mechanisms to persist for long periods within host epithelial cells in a viable but non-cultivable state. The co-infections of CT with the most frequently reported sexually transmitted viruses: human immunodeficiency virus (HIV), human papillomavirus (HPV), and herpes simplex virus (HSV) have been investigated through in vitro and in vivo studies. These research studies have made significant strides in unraveling the intricate interactions between CT, these viral STIs, and their eukaryotic host. In this review, we present an overview of the epidemiology of these co-infections, while specifically delineating the underlying mechanisms by which CT influences the transmission and infection dynamics of HIV and HSV. Furthermore, we explore the intricate relationship between CT and HPV infection, with a particular emphasis on the heightened risk of cervical cancer. By consolidating the current body of knowledge, we provide valuable insights into the complex dynamics and implications of co-infection involving CT and sexually transmitted viruses.

Evolutionary Dynamics in the Genome of Ocular Chlamydia trachomatis Strains from Northern Tanzania, pre- and post- Mass Drug Administration

“…Trachoma is a blinding disease caused by repeated infection of the eyes with Chlamydia trachomatis (Ct) serovar (Sv) A, B, Ba and C [1,2]. Ct is the leading cause of bacterial sexually transmitted infections globally [3,4]. In 1998, the World Health Organisation (WHO) introduced the SAFE strategy to eliminate trachoma as a public health problem by 2020 [5,6].…”

Trachoma and the Importance of Sexual Infective Route in Developed Countries. Comment on Gallenga et al. Why the SAFE—S Strategy for Trachoma? Are Musca sorbens or Scatophaga stercoraria Really the Culprit?—A Brief Historical Review from an Italian Point of View. Pathogens 2023, 12, 1419

“…In fact, the WHO (World Health Organization) has reported that over one million people contract sexually transmitted infections daily [7]. Thus, Ct is far from being eliminated unless a sexual strategy is implemented in the SAFE program.…”