In vitro Survival Characteristics of Koala Chlamydiae
Catherine M. RushA and Peter TimrnsAB
ACentre for Molecular Biotechnology, School of Life Science, Queensland University of Technology, Box 2434, Brisbane, Qld 4001, Australia.
BTo whom correspondence should be addressed.
Chlamydia is a significant cause of disease in the koala. The mechanism of transmission of the urogenital strain of koala Chlamydia (Type II) is assumed to be via sexual contact; however, the mechanism of transmission of the conjunctival strain (Type I) is less certain. In this study the extracellular stability of both koala chlamydial strains, Types 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 Eucalyptus spp. leaves. Koala Types I and II, as well as avian psittacosis elementary 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°C, but at lower temperatures (18-23°C) the elementary bodies remained viable for up to 28 days. Koala Type I elementary bodies also survived for 2-4 days after drying, whereas avian chlamydiae persisted slightly longer (4-6 days). The koala Type I isolate 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 significant time periods and suggest that non-sexual transmission of this chlamydiae may be possible.