Culture of sheep Chlamydia in a sheep fibroblast cell culture.

Abortion and enteric isolates of Chlamydia psittaci from sheep differed in their growth in a fibroblastic cell culture derived from the small intestine of a lamb. Twenty abortion isolates, each from a different farm, produced large inclusions which could be passaged several times whereas 10 enteric isolates each from different farms (but from some of the farms of origin of the abortion isolates) produced sparse inclusions which could not be passaged. This appears to be a rapid method of distinguishing abortion and enteric isolates and may indicate different nutritional requirements or be related to the invasiveness of the isolates.