Waddlia chondrophila: from a bovine abortigenic agent to a potential cause of human adverse pregnancy outcomes

Waddlia chondrophila is a strict intracellular bacterium belonging to the Chlamydiales order, which also encompasses important human and animal pathogens, including Chlamydia trachomatis and Chlamydia psittaci. Like all other members of the order, W. chondrophila displays a biphasic developmental cycle, alternating between infectious extracellular and replicative intracellular forms.First isolated from a bovine aborted foetus, W. chondrophila was later demonstrated to be associated, in women, with adverse pregnancy outcomes, such as miscarriage. Furthermore, recent studies have demonstrated a high prevalence of anti-W. chondrophila antibodies in asymptomatic women who consulted doctors regarding infertility problems, and in the male patients of infertile couples. Additionally, a role for this bacterium in respiratory tract infections has been suggested, as it has also been recovered from respiratory samples.Although the cause of miscarriage is not identified in ∼50% of cases, nowadays, no systematic diagnostic testing for the presence of W. chondrophila is routinely performed. Implementing large-scale testing in women with reproductive health issues would undoubtedly increase our knowledge of W. chondrophila prevalence and its implications for disease outcomes.