Clinical, pathological, and genetic characterization of Listeria monocytogenes causing sepsis and necrotizing typhlocolitis and hepatitis in a foal.

The research is about a case study of a five-week old filly who was infected by a virulent strain of Listeria monocytogenes, which caused her severe health issues and eventually led to her euthanization.

Infection and Condition of the Filly

• The filly was from an American Quarter Horse species and born in a properly managed breeding facility. The mother did not have any complications during and after birth.
• At 8 hours old, the immune system of the filly was developed adequately. However, she later showed symptoms like intermittent, mild diarrhea that was controlled using gastrointestinal protectants and probiotics.
• The health condition of the filly deteriorated due to the infection despite aggressive treatment, leading her to be humanely put down.

Postmortem Examination and Findings

• An autopsy of the filly was carried out post euthanasia which revealed the presence of severe hepatitis with necrosis and fibrinonecrotic typhlitis and colitis.
• Examination of the filly’s blood, liver, lungs, cecum (the first part of the large intestine), and colon confirmed that it was the Listeria monocytogenes bacterium.
• The bacterium was found in the blood, as well as in key organs, demonstrating the spread of the infection throughout the filly’s body which may have caused her lethargy, fever, ataxia (lack of voluntary coordination of muscle movements), and seizure activity.

Genetic Investigation of the Bacterium

• The bacterium was further identified using a technique called multiplex polymerase chain reaction (PCR). This method showed that the bacterium, which was responsible for the condition of the filly, was a virulent strain of Listeria monocytogenes.
• This information is important as it can assist in understanding the disease’s transmission, clinical manifestation, response to treatment, and potential prevention in the future.

This research offers insights into the pathological impact of a specific virulent strain of Listeria monocytogenes on equine patients, which can help in devising efficient therapeutic strategies.