Observation on the bacterial population of the os cervix of the ewe before and after embryo death.

Bacterial samples were isolated from the os cervix of mature Merino ewes during a normal oestrous cycle and after colchicine treatment which killed the 25-day old embryos. The population of bacteria was small during the oestrous cycle and consisted of Achromobacter spp. Alcaligenes spp, Corynebacterium spp, Bacillus spp and Escherichia coli. There was a significant increase in the numbers of bacteria isolated and a change in the proportions of the bacteria isolated from ewes after embryo death. Much greater numbers of potentially pathogenic organisms, including Pasteurella multocida, Corynebacterium pyogenes, Staphylococcus spp and Streptococcus spp were isolated after embryos were killed. It is suggested that persistence of potential pathogens in the vagina may impair fertility in ewes at the first oestrus after embryo death.