Tricuspid valve endocarditis in a horse owner, caused by Streptococcus equi subsp. zooepidemicus.
Abstract: subsp. (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. Unassigned: 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. Unassigned: 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.
Copyright © 2025 Roy et al.
Publication Date: 2025-07-31 PubMed ID: 41244977PubMed Central: PMC12530231DOI: 10.1128/asmcr.00059-25Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
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Summary
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Overview
- This research article reports the first known case of tricuspid valve endocarditis in a human caused by Streptococcus equi subsp. zooepidemicus (SESZ), a bacterium usually associated with animals such as horses.
- The study highlights the zoonotic potential of SESZ, the diagnostic challenges, and the clinical course requiring surgical intervention.
Background on Streptococcus equi subsp. zooepidemicus (SESZ)
- SESZ is a subspecies of group C streptococci commonly found in animals, particularly horses and llamas.
- It is considered zoonotic, meaning it can be transmitted from animals to humans, but such infections are rare.
- In humans, SESZ rarely causes serious infections such as infective endocarditis, an infection of the inner lining of the heart valves.
Patient Presentation and Diagnosis
- The case involved a 58-year-old woman presenting with symptoms of fever, malaise, and polyarthritis (inflammation in multiple joints).
- Clinical evaluation identified that the infection had affected her native tricuspid valve, one of the heart’s valves, leading to SESZ endocarditis.
- Genetic analysis of the SESZ strain isolated from the patient showed a close relationship to a clone involved in an outbreak of post-streptococcal glomerulonephritis (a kidney disease) in Brazil linked to unpasteurized cheese.
- The patient had no history of consuming unpasteurized cheese but was a horse rider, implying possible zoonotic transmission via contact with horses.
Clinical Course and Treatment
- The patient experienced persistent fever even while receiving combination antibiotic therapy, indicating a complicated infection.
- Due to the poor response to medication, surgical intervention was necessary, including replacement of the tricuspid and aortic valves and repair of the mitral valve.
- The case illustrates that SESZ endocarditis can be severe, requiring more than just antibiotics for resolution.
Significance and Implications
- This report is notable as the first documented case of native tricuspid valve endocarditis caused by SESZ in a human, expanding understanding of the clinical spectrum of SESZ infections.
- It highlights the importance of detailed exposure histories, particularly animal contact, in diagnosing rare causes of infective endocarditis.
- The case underscores the zoonotic risk posed by SESZ in horse owners and the potential for transmission through close animal contact rather than food sources alone.
- Clinicians should consider SESZ as a possible pathogen in patients with infective endocarditis who have animal exposure, especially when standard antibiotic treatments fail.
Cite This Article
APA
Roy CN, Wiechmann CE, Dev A, Walther BK, Musser JM, Olsen RJ, Beres SB, Axell-House DB.
(2025).
Tricuspid valve endocarditis in a horse owner, caused by Streptococcus equi subsp. zooepidemicus.
ASM Case Rep, 1(5), e00059-25.
https://doi.org/10.1128/asmcr.00059-25 Publication
Researcher Affiliations
- Department of Medicine, Houston Methodist Hospital, Houston, Texas, USA.
- Department of Medicine, Houston Methodist Hospital, Houston, Texas, USA.
- Department of Medicine, Houston Methodist Hospital, Houston, Texas, USA.
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA.
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA.
- Center for Infectious Diseases, Houston Methodist Research Institute, Houston, Texas, USA.
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College and Cornell-Presbyterian Medical Center, New York, New York, USA.
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA.
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA.
- Center for Infectious Diseases, Houston Methodist Research Institute, Houston, Texas, USA.
- Division of Infectious Diseases, Department of Medicine, Houston Methodist Hospital, Houston, Texas, USA.
- Department of Medicine, Weill Cornell Medical College, New York, New York, USA.
Conflict of Interest Statement
The authors declare no conflict of interest.
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