Streptococcus equi Subspecies zooepidemicus Endocarditis and Meningitis in a 62-Year-Old Horse Rider Patient: A Case Report and Literature Review

Abstract

The present article presents a case report and literature review concerning the Streptococcus equi subspecies zooepidemicus (SEZ), a rare zoonotic pathogen in humans. The case involves a 62-year-old man with no prior heart disease, presenting with endocarditis, pneumonia, and meningitis following close contact with a horse. The patient underwent urgent aortic valve replacement due to severe valvular damage caused by the infection. Blood and cerebrospinal fluid cultures confirmed the presence of SEZ, and the patient was treated with a combination of antibiotics, followed by a successful step-down to oral therapy using linezolid. A review of 25 additional Streptococcus equi endocarditis cases highlights the rarity of the condition, its association with animal contact, and its tendency to cause multi-site infections, such as pneumonia and meningitis. Early diagnosis, appropriate antibiotic therapy, and, in severe cases, surgical intervention are critical for a favorable outcome. This report emphasizes the importance of recognizing zoonotic infections in at-risk populations and the potential need for public health surveillance in these scenarios.

Keywords: Streptococcus equi; antibiotic therapy; aortic valve replacement; infective endocarditis; meningitis; pneumonia; zoonosis; zoonotic infection.

Figure 1

Chest X-ray shows multiple bilaterally diffused areas of predominantly perihilar interstitial–alveolar involvement, with near-complete opacification of both lungs.

Figure 2

TTE reveals mobile vegetation on aortic valve measuring (a) 8.63 mm and (b) 18.48 mm. Left Ventricle (LV), Ascending Aorta (AsAo).