Novel Chlamydia species isolated from snakes are temperature-sensitive and exhibit decreased susceptibility to azithromycin

Chlamydia species have recently been recognized as emerging pathogens in snakes. However, isolation of novel snake chlamydiae is critical and their growth characteristics are largely unknown. In this study, two novel chlamydial species are described: Chlamydia serpentis and Chlamydia poikilothermis, isolated after attempts on 23 cloacal and choanal swabs from 18 PCR-positive captive snakes originating from different Swiss snake collections. Isolation success, growth curve and infectivity rates over a 48-hour time period were dependent on temperature (37 °C for C. serpentis, 28 °C for C. poikilothermis). C. serpentis and C. poikilothermis were sensitive to tetracycline and moxifloxacin during evaluation by in vitro antibiotic susceptibility assay but intermediate to resistant (2–4 μg/ml) to azithromycin. Whole genome sequencing of the isolates provided proof of the novel species status, and gives insights into the evolution of these branches of genus Chlamydia.