Effects of embryo-freezing and thawing techniques on the survivability of Brucella abortus

A suspension of a pathogenic strain (2308) of Brucella abortus was aliquoted, centrifuged, resuspended in 6 treatment media and quantitated. Ten 1-ml samples of each treatment were subjected to a standard embryo-freezing technique. The treatments were selected to examine the effects of 1) freezing and thawing, 2) cryoprotectants and 3) antibiotics on the survivability of Brucella suspended in embryo-support media. Five samples of each treatment were thawed and quantitated after a 2-wk storage period and five samples were thawed and quantitated after a 6-mo storage period. Means and percent reductions were determined for each treatment. There was no statistical difference between means at 2 wk and 6 mo within any treatment. Freezing and thawing caused a 64% reduction in the number of viable Brucella . The addition of antibiotics caused a 99.9% reduction in viability of the organism. Glycerol protected the organism during freezing and thawing in the absence of antibiotics but did not interfere with the high percent reduction seen when antibiotics were present. Dimethylsulfoxide (DMSO), however, not only protected the organism during freezing and thawing but also appeared to negate the effects of the antibiotics.