Case of the Month - January 2023 A 13-year-old girl presented to the Emergency Room with a swollen and painful left thumb. Eight days earlier, she had picked out a hangnail from the medial side of the thumb, resulting in the swelling and pain. She had been prescribed amoxicillin-clavulanate, with no improvement. Physical examination revealed a tender circumferential swelling of the right thumb from the flexion joint to the tip, with a paronychia 1 cm in length and fluctuance extending proximally for an additional 0.5 cm. The wound was incised, and the drainage was sent for culture. The culture grew a moderate quantity of small, nonhemolytic colonies that showed “pitting” appearance on blood (Figure 1) and chocolate (Figure 2) agar. There was no growth on MacConkey agar. The colonies were oxidase-positive and smelled like bleach. What is the organism? Figure 1. Growth on blood agar. Figure 2. Growth on chocolate agar.
