Pasteurella multocida lab profile: Oxidase positive; OF test (O+/F+); nonmotile; no growth on MAC.

Pasteurella multocida lab profile: Oxidase positive; OF test (O+/F+); nonmotile; no growth on MAC.

• A. Oxidase positive; OF test (O+/F+); nonmotile; no growth on MAC
• B. Oxidase positive; OF test (O+/F-); motile; growth on MAC
• C. Oxidase negative; OF test (O+/F+); nonmotile; growth on MAC
• D. Oxidase positive; OF test (O-/F+); nonmotile; no growth on MAC

Answer: (A)

Pasteurella multocida has a lab profile that fits this set of traits: it is oxidase positive, the OF test shows a fermentative pattern (O+/F+), it is nonmotile, and it does not grow on MacConkey agar. Oxidase positivity helps distinguish it from oxidase-negative Gram-negative rods. A fermentative OF result (O+/F+) means the organism can metabolize glucose both with and without oxygen, which is typical for Pasteurella rather than strictly oxidative or strictly fermentative organisms. Being nonmotile matches its characteristic lack of flagellar movement. The lack of growth on MacConkey agar reflects its poor growth or failure to thrive on that medium, which is consistent with Pasteurella’s growth preferences. The other profiles fail to match at least one of these key traits (oxidase status, OF pattern, motility, or MAC growth), making A the best fit.

Pasteurella multocida has a lab profile that fits this set of traits: it is oxidase positive, the OF test shows a fermentative pattern (O+/F+), it is nonmotile, and it does not grow on MacConkey agar. Oxidase positivity helps distinguish it from oxidase-negative Gram-negative rods. A fermentative OF result (O+/F+) means the organism can metabolize glucose both with and without oxygen, which is typical for Pasteurella rather than strictly oxidative or strictly fermentative organisms. Being nonmotile matches its characteristic lack of flagellar movement. The lack of growth on MacConkey agar reflects its poor growth or failure to thrive on that medium, which is consistent with Pasteurella’s growth preferences. The other profiles fail to match at least one of these key traits (oxidase status, OF pattern, motility, or MAC growth), making A the best fit.