Haemophilus influenzae biogroup aegyptius requires which growth factors, and what is its delta-aminolevulinic acid status?

• A. Indole negative; Requires V factor; ALA negative
• B. Indole negative; Requires X and V factors; ALA positive
• C. Indole positive; Requires X and V factors; ALA negative
• D. Indole negative; Requires X and V factors; ALA negative

Answer: (D)

Growth relies on external heme and NAD; Haemophilus species that require both X factor (hemin) and V factor (NAD) must have access to these nutrients in the medium to grow. The biogroup aegyptius variant of Haemophilus influenzae is indole negative, which fits the typical profile of this genus. Its delta-aminolevulinic acid status being negative means it does not produce porphyrins in the standard ALA (delta-ALA) test, and exogenous ALA does not alter its phenotype in this context. Putting those traits together, this organism is indole negative, requires X and V factors, and is negative for the delta-ALA test.