Infectious Aortitis and Mycotic Abdominal Aneurysm Secondary to Cat Bite Injury

A recent report describes a case of infectious aortitis and resultant mycotic abdominal aneurysm that arose as rare complications of exposure to Pasteurella multocida from a cat bite in a male patient.

Dennis Dane Cho, from the University of Toronto, Ontario, Canada, and colleagues published their clinical case report online in the World Journal of Clinical Cases.

“We suspect that the non-dermal complications of cat bites are underappreciated in the ED [emergency department],” the authors write. “Given how frequently animal bites are encountered in the ED, emergency physicians should be aware of aortitis and mycotic aneurysm as a delayed sequelae of cat bites.”

The 68-year-old man presented to the ED after falling at home. At the time of presentation, he appeared generally unwell, had generalized abdominal pain, and was wheezing. He had also been experiencing chills, and had lost approximately 22 lbs of his body weight in the past two weeks. He reported that, four weeks previously, a cat had bitten his right thumb and he had received antibiotics to treat the resultant cellulitis. However, at the time of presentation to the ED, the skin wound appeared to have resolved. The patient also reported a history of heavy alcohol use.

Nevertheless, many clinical findings in the patient suggested a diagnosis of sepsis. The man was tachycardic (120 beats per minute), hypotensive (80/60 mmHg), and hypoxemic (86% oxygen saturation). Pertinent laboratory findings included an elevated white blood cell count and elevated lactate level. The patient also had renal failure with a creatinine level of 197 μg/L and an elevated urea level of 31 mmol/L.

Ultrasound examination also identified a large, 10 cm-wide aneurysm in the abdominal aorta, and a computed tomography scan showed that the aneurysm had ruptured. The patient underwent surgery, which included washout of the aortic bed and repair of the aorta with a tube graft. The patient also received intravenous antibiotic therapy. Microbial culture of samples of the patient’s blood and aorta yielded growth of the bacterium Pasteurella multocida.

Despite aggressive treatment, the patient’s condition deteriorated and he died two weeks after surgery.

Pasteurella multocida is commonly found in pets' mouths. And, although cat bites are less common than dog bites, cat bites more frequently become infected. This is because cats have sharp, narrow teeth that can penetrate more deeply than a dog’s teeth, and thereby carry bacteria deeper into the wound. These puncture wounds also rapidly seal over, allowing bacteria from the cat’s mouth to become trapped below the injured person’s skin, multiply, and spread in the adjacent tissues.

According to the authors, cases of animal bites are common, comprising 330,000 ED visits per year in the United States, and resulting in 10,000 hospitalizations and 20 deaths. Although aortitis is a rare and delayed complication of pasteurellosis, they stress that it should be considered in a septic patient with a history of a bite injury, especially in a one who is immunocompromised—as in the case of this patient with a history of heavy alcohol use. “A high index of suspicion is necessary to facilitate early imaging, antibiotics, and surgical management,” the authors conclude.

Dr. Parry graduated from the University of Liverpool, England in 1997 and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals, and has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.