Smooth gray colonies were isolated from an infected cat scratch on BAP and CHOC. The organism showed no growth on MAC. Gram stain revealed small gram-negative coccobacilli. You would expect this organism to be

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The organism described is likely Pasteurella multocida, a small gram-negative coccobacillus commonly isolated from animal infections, such as cat scratches. It is known to grow on Blood Agar Plate (BAP) and Chocolate Agar (CHOC) but not on MacConkey Agar (MAC), indicating it does not ferment lactose. Pasteurella multocida is both oxidase and catalase positive.

Smooth Gray Colonies Were Isolated from an Infected Cat Scratch