Criblamydia sequanensis Harbors a Megaplasmid Encoding Arsenite Resistance.

Criblamydia sequanensis is an amoeba-resisting bacterium recently isolated from the Seine River. This Chlamydia-related bacterium harbors a genome of approximately 3 Mbp and a megaplasmid of 89,525 bp. The plasmid encodes several efflux systems and an operon for arsenite resistance. This first genome sequence within the Criblamydiaceae family enlarges our view on the evolution and the ecology of this important bacterial clade largely understudied so far.

Predator or prey? Chlamydophila abortus infections of a free-living amoebae, Acanthamoeba castellani 9GU.

Limited evidence exists to suggest that the ability to invade and escape protozoan host cell bactericidal activity extends to members of the Chlamydiaceae, intracellular pathogens of humans and animals and evolutionary descendants of amoeba-resisting Chlamydia-like organisms. PCR and microscopic analyses of Chlamydophila abortus infections of Acanthamoeba castellani revealed uptake of this chlamydial pathogen but, unlike the well-described inhabitant of A. castellani, Parachlamydia acanthamoebae, Cp. abortus did not appear to propagate and is likely digested by its amoebal host. These data raise doubts about the ability of free-living amoebae to serve as hosts and vectors of pathogenic members of the Chlamydiaceae but reveal opportunities, via comparative genomics, to understand virulence mechanisms used by Chlamydia-like organisms to avoid amoebal digestion.

Evidence for Parachlamydia in bovine abortion.

Bovine abortion of unknown infectious aetiology still remains a major economic problem. In this study, we focused on a new possible abortigenic agent called Parachlamydia acanthamoebae. Retrospective samples (n=235) taken from late-term abortions in cattle were investigated by real-time diagnostic PCR for Chlamydiaceae and Parachlamydia spp., respectively. Histological sections of cases positive by real-time PCR for any Chlamydia-related agent were further examined by immunohistochemistry using specific antibodies. Chlamydophila abortus was detected only in three cases (1.3%) by real-time PCR and ArrayTube Microarray playing a less important role in bovine abortion compared to the situation in small ruminants in Switzerland. By real-time PCR as many as 43 of 235 (18.3%) cases turned out to be positive for Parachlamydia. The presence of Parachlamydia within placental lesions was confirmed in 35 cases (81.4%) by immunohistochemistry. The main histopathological feature in parachlamydial abortion was purulent to necrotizing placentitis (25/43). Parachlamydia should be considered as a new abortigenic agent in Swiss cattle. Since Parachlamydia may be involved in lower respiratory tract infections in humans, bovine abortion material should be handled with care given the possible zoonotic risk.