Systemic Streptococcus equi infection in a horse handler–a case of human strangles.

The research article discusses a case of a horse handler contracting bacteremia and cellulitis due to Streptococcus equi, a bacteria usually seen in horses causing a severe respiratory disease named strangles. This human infection case is unique due to the rarity of human transmission of this bacteria.

Case Description

• A 56-year-old man who had worked for two decades as a horse handler arrived at the hospital with a four-day history of swelling and pain on the right side of his face. He had also experienced fevers, night sweats, and rigors two days before hospital admission.
• The facial swelling began at the angle of the right mandible (jawbone), spread to involve the right parotid (salivary gland), and sub-maxillary (under the jaw) region.
• Redness and swelling spreads into his neck and chest area. Additionally, he had a persistent dry cough.
• Upon physical examination, the patient was disheveled but in no distress. The right side of his face was erythematous (red), warm, and considerably swollen. Erythema and mild induration (hardening of an area of the body due to inflammation) were also noted over the anterior chest and abdomen.
• His initial blood tests displayed an elevated leukocyte count (indicative of inflammation or infection).
• An aspirated wound sample revealed Gram-positive cocci in chains and Gram-negative rods (types of bacteria), and two blood cultures grew a β-hemolytic Streptococcus sensitive to bacitracin.
• These organisms were identified as group C Streptococcus equi based on the lack of fermentation of trehalose, lactose, and sorbitol.
• The patient was treated with penicillin and required surgical drainage of infected fluid from his face. His condition improved gradually over the span of two weeks, with the resolution of cellulitis three weeks after admission.

Significance of This Case

• This case underscores the rarity and potential severity of zoonotic infections, or infections that can be transmitted from animals to humans. The patient presumably contracted the Streptococcus equi infection through his close contact with horses in his work as a handler.
• Although none of the horses at the stable were recently ill, it’s essential to note that zoonotic diseases can be transmitted even if animals are asymptomatic.
• This case contributes to the limited evidence of human infection with Streptococcus equi and emphasizes the need for heightened awareness among individuals with close and frequent contact with horses.