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

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

Answer: (D)

Haemophilus influenzae biogroup aegyptius is a fastidious bacterium that must have both X (hemin) and V (NAD) factors to grow. On media lacking these nutrients, it won’t appear unless those factors are provided, which is why chocolate agar or media supplemented with X and V support its growth. The delta-aminolevulinic acid status refers to whether the organism needs ALA supplementation to synthesize heme. A negative status means it does not require external ALA for growth, indicating it does not depend on ALA supplementation to obtain heme. Putting these together, this organism both needs X and V and does not require ALA supplementation, which aligns with the described characterization.