X and V Factor Disks are paper disks impregnated with X (hemin) and V (nicotinamide adenine dinucleotide – NAD) growth factors. They are used for the differentiation of Haemophilus species.
X and V Factor Disks
Haemophilus influenzae require both X and V factor to grow while Haemophilus parainfluenzae requires V factor only for grow. Haemophilus ducreyi requires only X factor without need of V factor. We usually use Mueller Hinton Agar for the disk test.
Haemophilus influenzae growth around X – V Factors Disk
Here is a table for Haemophilus species growth Around X – and V-Factor Disks:
Haemophilus species growth dependent on X and V Factor
