Case 50

1. Presented by Harsimar Kaur, MBBS and reviewed by Karen Carroll, MD.

An adult patient presented to the hospital following a cat bite. According to the patient, they were bitten by a feral cat. Over the day the patient noted increased redness and swelling to the area and significant pain. The patient was febrile and tachycardic. The patient's hand examination showed 3 cm wound with crusting drainage surrounded by erythema on the dorsum of the left hand (Figure A). The patient's left hand range of motion was limited by pain, but allowed passive extension. Laboratory results showed that the patient had leukocytosis, with white blood count elevated at 15,000/ cubic mm. Blood cultures were drawn and the patient was started on ampicillin-sulbactam. The patient underwent bedside drainage of the wound by plastic surgery and received tetanus prophylaxis as well.

Gram stain performed on a positive blood culture showed gram negative rods (Figures B and C).

Figure A: Image showing cat bite wound on the dorsum of patient's hand.

Figures B and C: Gram stain performed on positive blood culture shows gram negative rods.

Question: What is the most likely cause of the patient's infection?