Equine abortion associated with Enterobacter agglomerans.

The research article is about a study that investigates the role of Enterobacter agglomerans in causing horse abortions, providing information on the pathology and microbiology of the cases.

Study Background

• The researchers focused on the role of Enterobacter agglomerans, previously known as Erwinia herbicola, in causing horse abortions.
• Enterobacter agglomerans is a bacterium in the family Enterobacteriaceae that is widely found in the environment and is known to live on plant surfaces. Although usually a saprophyte (an organism living on dead or decaying organic matter), it can also act as an opportunistic pathogen in humans, causing severe and occasionally fatal infections.
• Previous routine diagnostic investigations on aborted horse fetuses showed that Enterobacter agglomerans were frequently detected, often exclusively, leading the researchers to hypothesize that it was the primary pathogen involved in horse abortions.

Materials and methods

• During the study, specimens from horse abortion cases were received at the institution for testing. Field autopsies were performed on twelve of the specimens by private practice veterinarians.
• Various tissue samples, including some from fetuses and fetal membranes, were collected for histological examination. The samples were processed and sectioned and stained with several different methods.
• Small pieces of the formalin-fixed fetal lung and chorioallantois, a combined fetal membrane, were further examined using electron microscopy after being post fixed in glutaraldehyde and osmium tetroxide and embedded in Spurr’s resin.
• For bacteriological culture, primarily lung, liver, heart blood, and stomach from 15 fetuses as well as the fetal membranes from 3 of the fetuses were plated on several types of media. Two other fetal samples were not cultured, but swabs were taken following abortion and processed.

Results

• Of the 108 horse abortion cases investigated between August 1978 to May 1980, Enterobacter agglomerans was isolated from either the fetus or fetal membranes in 17 cases.
• The gestational age at which abortions occurred ranged between 180 and 320 days, with an average of 260 days. Crown-rump lengths varied between 60 and 95 cm.
• The noticeable pathological changes in the affected fetuses were minimal. Gross changes, when present, included enlarged and friable livers with orange-yellow discoloration and lung abnormalities.