Case of the Month - September 2019 Case of the month archive A 61 year old man with long history of chronic rhinosinusitis presented to the clinic. He had sinus problems since childhood, mainly on the right side. The patient states that he received multiple vaccinations during his childhood, but not sure what they are. He has had mild improvement in his symptoms while on azelastine (an antihistamine), fluticasone (a steroid), and saline nasal rinses. He was tested for allergies in the past and results came back negative. Nasal endoscopy results are notable for partially truncated and middle turbinates, green crusting on both lateral nasal walls, mucopurulence from both maxillary sinuses, and crusting and mucopurulence in both sphenoethomoidal recesses. Results of cultures obtained during endoscopy and sent to the Microbiology Laboratory are shown in the figures below, with descriptions. What is the organism? Figure 1: white, dry colonies growing from a subculture onto 5% sheep blood agar. The organism is catalase-positive. Figure 2: black colonies on cysteine-tellurite medium. Figure 3: Gram stain showing Gram-positive, short and slightly curved rods, with rounded edges arranged in palisades of parallel cells or in pairs of cells occasionally forming “L” shapes.