Biology and pathogenicity of "Waddlia chondrophila"

Abstract

This thesis investigates the pathogenicity of a Chlamydia-related bacterium: Waddlia chondrophila, which is suspected to cause abortion in bovines as well as miscarriages in humans. Macrophages represent the first line of defense of the innate immunity against invading pathogens, we thus studied the interaction between W. chondrophila and human macrophages. We observed thal W. chondrophila multiplied very efficiently inside monocyte-derived macrophages.
Diagnostic tools to detect obligate intracellular bacteria are lacking so we developed a Waddtia specific realtime PCR based on the 163 rRNA encoding gene. Since W. chondrophrla could be involved in human miscarriage, we analyzed samples from women having miscarriage or uneventful pregnancy. Waddlia serologies results confirmed an association between the presence of W. chondrophrla antibodies and miscarriage (23.2% versus 14.6% in the control group, p-value 0.044).
As W. chondrophila's pathogenicity was suggested, we studied its antibiotic susceptibility. W. chondrophila revealed to be susceptible to macrolides and tetracylines but resistant to beta-lactams and fluoroquinolones. This resistance to fluoroquinolones could be explained by mutations in the quinolone resistance determining region of the gyrase (GyrA) and topoisomerase lV (ParC) encoding genes. ln conclusion, this thesis allowed to precise the role of W. chondrophila in human miscarriage. However, more studies will be necessary to fully understand the pathogenesis of W. chondrophila in adverse pregnancy outcomes.