The patient is a 61-year-old, Native American female with history of bioprosthetic mitral valve, presenting with increased dyspnea, cough, diarrhea, and fever for two weeks. Ceftriaxone and azithromycin were started for right middle lobe infiltrate seen on chest X-ray and suspected pneumonia.
Initial physical examination revealed a new prominent murmur and blood cultures were positive for Streptococcus zooepidemicus. She denied intravenous drug use, was HIV negative, had no neutropenia, nor was she taking immunosuppressive medications. TTE was performed and showed a large mobile vegetation adherent to the atrial surface of the posterior mitral valve leaflet, measuring 1 cm in diameter.
On detailed physical exam the patient was found to have flat, painless macules on the tips of her fingers, likely Janeway lesions, which are rarely seen in clinical practice. Her S. zooepidemicus culture was sensitive to ceftriaxone, which will be continued for 6 weeks with repeat TTE after completion of her antibiotic course.
On further questioning the patient disclosed she is retired but keeps a stable and had recent superficial perinasal wounds while in continuous contact with her horses and dog. The horses did not show any signs of respiratory illness. However, the patient’s dog had three weeks of bilateral mucopurulent nasal discharge, lower respiratory tract symptoms and a new murmur. Of note, the dog had free access to the horses. Discussion with the dog’s veterinarian revealed the dog was started on clindamycin, but no blood cultures had been drawn. The decision to start clindamycin was actually determined from the admitted patient’s sensitivity results.
Discussion:
Streptococcus zooepidemicus is a Lancefield group C streptococcus and zoonotic pathogen for those in close contact with horses, or who consume homemade cheese or unpasteurized milk. S. zooepidemicusis a member of the normal upper respiratory, skin, and urogenital equine flora. It is not considered a part of human or canine normal flora.
Streptococcus Zooepidermicus rarely infects humans, and usually spreads from animals via direct contact. Most human cases occur sporadically. Symptoms are initially flu-like with fever, chills, and prostration. The incubation period is usually short; 1-3 days. Gastrointestinal symptoms are common, although gastrointestinal tract infection itself is uncommon. More severe human infections have been associated with consumption of unpasteurized milk, often from cows with mastitis. Cases of endocarditis, meningitis, septic arthritis and post-streptococcal glomerulonephritis have been reported with this organism.
Conclusions:
The importance of conducting a thorough history and physical examination cannot be overstated, especially when practicing in rural locations with patient populations who are risk for zoonotic infections. Furthermore, by communicating with all healthcare allied professions, even veterinarians, we can better understand the pathogens and risk exposures our patients face in unique settings.