Haemophilus aegyptius requires which factors?

• A. Requires X factor
• B. Requires V factor
• C. Requires X and V factor
• D. Aminolevulinic acid positive

Answer: (C)

Haemophilus species are fastidious bacteria that need specific growth factors. X factor is hemin, and V factor is NAD. Haemophilus aegyptius requires both of these factors to grow, so you’ll see colonies on media that provide both—such as chocolate agar, where red blood cells are lysed and release X and V, or on media supplemented with both factors. If only one factor is present, growth is poor or absent. The aminolevulinic acid test is a separate biochemical characteristic and does not define the growth factor requirement here. So the correct understanding is that Haemophilus aegyptius needs both X and V factors.