IN-VITRO SURVIVAL CHARACTERISTICS OF KOALA CHLAMYDIAE

Chlamydia is a significant cause of disease in the koala. The mechanis m of transmission of the urogenital strain of koala Chlamydia (Type II ) is assumed to be via sexual contact; however, the mechanism of trans mission of the conjunctival strain (Type I) is less certain. In this s tudy the extracellular stability of both koala chlamydial strains, Typ es I, and II, were compared with that of an avian C. psittaci strain. Koala and avian strains were subjected to various pH, temperature and desiccation conditions and were also placed on the surface of Eucalypt us spp. leaves. Koala Types I and II, as well as avian psittacosis ele mentary bodies, survived 4 hours' exposure to solutions of pH 4.0-10.0 . Koala Type I survived best at pH 7.2-7.5 whereas Type II preferred a pH of 7.0-7.2. Koala Type I elementary bodies were inactivated after 5 min at 56 degrees C, but at lower temperatures (18-23 degrees C) the elementary bodies remained viable for up to 28 days. Koala Type I ele mentary bodies also survived for 2-4 days after drying, whereas avian chlamydiae persisted slightly longer (4-6 days). The koala Type I isol ate maintained infectivity for cell culture after 3 days' exposure on the leaves of Eucalyptus tereticornis. These results indicate that the koala Type I isolate is able to survive extreme conditions for signif icant time periods and suggest that non-sexual transmission of this ch lamydiae may be possible.