The adverse effect of dilution on the infectivity of Fusobacterium necrophorum culture.

Dilution had an adverse effect on the infectivity of 24 h cultures of a strain of Fusobacterium necrophorum, which became apparent at or near the minimum lethal dose. Thus in mice inoculated subcutaneously the mortality produced by 0.01 ml of undiluted culture was almost invariably greater than that produced by 0.1 ml of a 1 in 10 dilution. The explanation appeared to lie in the increased physical separation of bacterial cells that was the inevitable consequence of dilution.