Case Report : Streptococcus equi subspecies zooepidemicus bacteriemia and spondylodiscitis following direct contact with a horse.

Overview

• This case report documents a rare human infection caused by Streptococcus equi subspecies zooepidemicus, which occurred after direct contact with a horse and led to bloodstream infection and spondylodiscitis (spinal infection).

Background

• Pathogen: Streptococcus equi subspecies zooepidemicus is a bacterium commonly found in horses, colonizing their respiratory tracts and oral cavities.
• Zoonotic nature: It can occasionally infect humans, though such infections are rare.
• Typical human infections: When humans do get infected, it often manifests as bacteremia (bacteria in the blood), meningitis (infection of the membranes around the brain), or pneumonia (lung infection).
• Transmission: Typically linked to exposure to horses or consumption of unpasteurized dairy products.

Case Description

• Patient: An 88-year-old individual who had direct and exclusive contact with a live horse.
• Symptoms and clinical presentation: Developed bacteremia and spondylodiscitis, an infection involving the intervertebral discs and adjacent vertebrae of the spine.
• Diagnostic methods:
  • Blood cultures were used to detect and identify Streptococcus equi subspecies zooepidemicus in the bloodstream.
  • Magnetic resonance imaging (MRI) confirmed the presence of spondylodiscitis by visualizing inflammation and damage in the spinal structures.

Treatment and Outcome

• Antibiotic therapy: The patient underwent a lengthy antibiotic treatment course consisting of:
  • 45 days of intravenous ceftriaxone, a broad-spectrum cephalosporin antibiotic.
  • Followed by 10 days of oral levofloxacin, a fluoroquinolone antibiotic.
• Result: The patient showed favorable clinical evolution, meaning improvement and resolution of the infection.

Significance and Conclusions

• Novelty: This is reported as the first known case of spondylodiscitis caused by Streptococcus equi subspecies zooepidemicus linked directly and exclusively to contact with a live horse.
• Clinical implications: Healthcare providers should consider asking about horse exposure when diagnosing invasive streptococcal infections given the zoonotic potential.
• Awareness: Highlighting such rare zoonotic infections helps improve diagnosis, management, and prevention strategies in patients with relevant animal contact histories.