The growth pattern known as satellitism is associated with which organism?

The growth pattern known as satellitism is associated with which organism?

• A. Haemophilus influenzae
• B. Burkholderia pseudomallei
• C. Campylobacter jejuni
• D. Yersinia pestis

Answer: (A)

Satellitism describes Haemophilus influenzae growing as tiny colonies around a helper organism on blood agar. This happens because H. influenzae requires two growth factors: X factor (hemin) and V factor (NAD). On standard blood agar, these factors aren’t freely available, so the bacterium won’t grow well by itself. If a neighboring organism such as Staphylococcus aureus is present, it releases NAD and, through hemolysis or diffusion, creates a local environment rich in X and V factors. In that setting, Haemophilus influenzae forms small satellite colonies around the helper organism. This classic pattern points to Haemophilus influenzae, whereas the other listed bacteria do not display this satellitism on routine blood agar.