While playing in the park, an 8-year-old girl is bitten in the leg by a neighbor’s cat. She presents the next day with fever and bone pain localized to her right calf. X-ray reveals a lytic lesion of the right tibia. Results of the bone culture are pending. You expect the infecting organism to be ?
Correct Answer: Pasteurella multocida
Description: This patient has osteomyelitis due to a cat bite that penetrated the periosteum. Whenever you see dog or cat bites in a question stem, consider Pasteurella multocida as a primary cause of wound infection. This organism is a sho, encapsulated, gram-negative rod demonstrating bipolar staining. Rapidly arising cellulitis is paicularly indicative of this organism. Brucella melitensis is a small, acapsular, gram-negative rod that causes brucellosis (undulant fever) and is associated with contact with goats or sheep. Brucella abous and Brucella suis are variants associated with contact with cows and pigs, respectively. The organisms enter the body through the skin or through contaminated dairy products, such as unpasteurized impoed goat's milk or cheeses. Eikenella corrodens is commonly found in human bites. It is a gram-negative rod that is pa of the normal flora of the human mouth. Francisella tularensis is a small, pleomorphic, gram-negative rod that causes tularemia (rabbit fever). It occurs most commonly in rural areas. Ref: Ray C.G., Ryan K.J. (2010). Chapter 36. Plague and Other Bacterial Zoonotic Diseases. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.
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