# Tricuspid valve endocarditis in a horse owner, caused by Streptococcus equi subsp. zooepidemicus

## TL;DR

A horse owner developed a rare heart infection caused by bacteria linked to animals, highlighting the importance of considering animal exposure in diagnosing such cases.

## Contribution

This is the first reported case of tricuspid valve endocarditis caused by Streptococcus equi subsp. zooepidemicus in a human.

## Key findings

- The patient's infection was caused by a strain of Streptococcus equi subsp. zooepidemicus genetically linked to a Brazilian outbreak.
- The infection required valve replacement and repair despite antibiotic treatment.
- The case emphasizes the importance of exposure history in diagnosing zoonotic infections.

## Abstract

Streptococcus equi subsp. zooepidemicus (SESZ) are zoonotic group C streptococci primarily acquired from contact with horses and other animals, such as llamas. They are unusual causes of infection in humans and rarely cause infective endocarditis.

A 58-year-old woman presented with fever, malaise, and polyarthritis. Clinical evaluation diagnosed native tricuspid valve SESZ endocarditis. The SESZ isolate was genetically closely related to a clone causing an outbreak of post-streptococcal glomerulonephritis linked to the consumption of unpasteurized cheese in Brazil. The patient had no exposure to unpasteurized cheese but rode horses. Her infection course was notable for persistent fever despite combination antibiotic therapy. Resolution of her symptoms ultimately required tricuspid valve and aortic valve replacement and mitral valve repair.

This is the first reported case of native tricuspid valve SESZ endocarditis. The case demonstrates the natural history of this rare disease and illustrates the importance of taking an exposure history.