This is a 65–year–old male with diabetes and hypertension who presented to the emergency room with a complaint of right shoulder pain. He was also found to be febrile to 101.5 F with a tender, erythematous and swollen shoulder. A shoulder arthrocentesis was attempted but was unsuccessful in aspirating synovial fluid. Blood cultures were drawn and the patient left the emergency room against medical advice. The blood cultures grew positive for gram positive cocci and the patient was called to return to the emergency room. Further questioning revealed that he had a subjective fever for 3–4 weeks, mild fatigue, but otherwise no localizing signs or symptoms of infection other than his shoulder pain. He also noted that he lived on a ranch with horses, with one particular horse that had been sick with “distemper,” who had to be isolated from the rest of the animals. The patient was initially started on vancomycin and ceftriaxone until speciation of the blood culture revealed streptococcus equi. The patient was continued on ceftriaxone alone. His AC joint fluid analysis revealed WBC 3490, PMN 95%, and grew strep equi. The glenohumoral joint aspiration was unsuccessful in aspirating fluid after three separate attempts. The patient’s fever and leukocytosis resolved by day 2 of antibiotics, CRP decreased from 38.2 to 8.94, and a TTE revealed no vegetations. The patient was discharged with a 4–week course of IV ceftriaxone.
Streptococcus equi from group C streptococci is the etiologic agent for the upper respiratory disease in horses commonly referred to as strangles or distemper. The clinical signs in horses are fever, usually Lymphadenopathy, Mucopurulent nasal discharge, Pharyngitis and upper airway stridor. Subsequently, there is swelling of cervical nodes, which can drain purulent material. Transmission is direct horse–to–horse contact. Human infections are rare, but have been described in case reports. The clinical presentations in humans include pharyngitis, septicemia, meningitis, purulent arthritis and endocarditis. Poststreptococcal glomerulonephritis has also been described in connection with human infections The source of human infection is often traced back to contact with horses. Our case lived in a ranch, and bred horses. There were three cases of strangles in his horses, which they all had pustules with draining pus. Patient later commented that he did not use gloves in several occasions when he was cleaning the pustules. We believe that he got infected through direct contact, and the bacteremia caused the arthritis. He was treated successfully, and repeat cultures were negative.
Physicians should be aware of Streptococcus equi infection in humans. While a rare cause for infection in humans, should be considered in patients who have contact with horses.