Bovine bacterial abortion caused by Escherichia coli infection

Abstract

A 3‐year‐old, 500 kg Holstein cow aborted at 7 months of gestation. On histological evaluation of the fetal lungs, abundant neutrophils infiltrated the alveolar spaces, bronchi and bronchioles with intralesional Gram‐negative bacteria, immunolabelled with Escherichia coli immunohistochemistry. Aerobic bacterial culture of lung and abomasal contents yielded a pure growth of E. coli . The E. coli strain isolated was associated with the virulence gene fim H, phylogenetic group B1, and was serotype 08:H9. Abortions in cattle are sporadically triggered by opportunistic bacteria such as E. coli, Trueperella pyogenes, Staphylococcus aureus, Bacillus spp ., Histophilus somni and Streptococcus spp. Given the commensal and opportunistic nature of these bacteria, diagnosis must always rely on the isolation of nearly pure or pure E. coli cultures from tissue samples and fetal fluids, along with the presence of histopathological changes in the fetus or placenta and the exclusion of other abortive agents.