Horse to human: Streptococcus equi septicemia presenting as endogenous endophthalmitis.

Horse to human: Streptococcus equi septicemia presenting as endogenous endophthalmitis involves a rare systemic infection transmitted from a horse leading to vision loss, which was successfully treated with prompt medical and surgical intervention.

Introduction and Background

• The research focuses on a rare systemic infection caused by Streptococcus equi, a bacterium typically transmitted from horses to humans.
• This study highlights a case where the infection presented as endogenous endophthalmitis, a severe eye infection leading to vision loss.
• Endogenous endophthalmitis is an infection inside the eye originating from the bloodstream, which in this case was complicated by septicemia (blood infection).

Case Description

• The patient was a healthy polo player and horse trainer, suggesting close contact with horses, potentially providing the source of infection.
• He presented with loss of vision in the right eye, which raised suspicion of endogenous endophthalmitis secondary to septicemia.
• Blood cultures and vitreous (eye fluid) cultures rapidly identified Streptococcus equi as the causative agent.

Treatment Approach

• The treatment involved immediate administration of intravenous (systemic) antibiotics to control the septicemia.
• The patient underwent three vitrectomies, which are surgical procedures to remove the infected vitreous gel from inside the eye to reduce infection and inflammation.
• Two intravitreal antibiotic injections (direct antibiotic delivery into the eye) were given during the first week to manage local infection.
• This combined systemic and localized therapy aimed to eradicate the infection and prevent complications such as retinal detachment.

Outcomes

• The systemic infection was promptly controlled without progression to meningitis, a potentially fatal complication commonly associated with this bacterium.
• The patient’s vision in the affected eye recovered to near normal, achieving 20/30 visual acuity three months after infection.
• This positive outcome contrasts with previous reports where delayed or less aggressive treatment led to poor visual prognosis or death.

Significance and Conclusions

• The case illustrates the critical importance of early diagnosis by ophthalmologists when encountering endogenous endophthalmitis, particularly in patients with potential zoonotic (animal-to-human) exposures.
• Immediate and repeated surgical intervention combined with both intravitreal and systemic antibiotics can be lifesaving and vision-preserving.
• Recognizing rare pathogens like Streptococcus equi in systemic infections is crucial for guiding targeted therapy and improving patient outcomes.
• The study expands clinical awareness about this rare but serious condition and supports aggressive treatment protocols for similar cases.