Which organism matches the following profile: short Gram-negative bacillus; oxidase variable; X factor positive; V factor negative; XV factor positive; porphyrins negative?

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This profile is pointing to a fastidious, X-factor–dependent g negative organism with a unique pattern of growth factors and porphyrin metabolism. X factor positivity means it needs heme (often supplied by blood components) to grow, while V factor negativity indicates it does not rely on NAD for growth. The XV factor result being positive shows that growth is observed when both X and V factors are present, a pattern that helps distinguish certain Haemophilus species. The porphyrin test being negative means the organism cannot synthesize its own heme and must obtain it from the environment. Taken together, these traits describe Haemophilus ducreyi, the chancroid pathogen, which is a short gram‑negative bacillus with variable oxidase activity, X-factor dependence, lack of V-factor requirement, XV-factor growth pattern, and porphyrin negativity. The other organisms listed do not fit this combination of gram stain pattern and specific factor requirements.