Which organism grows around the V factor but not the X factor on factor V/X enriched media and is implicated in respiratory infections?

Prepare for the CAMLPR Microbiology Test. Utilize flashcards and engaging multiple-choice questions, each equipped with descriptions and explanations. Ready yourself for an excellent performance!

Growth factor requirements on X (hemin) and V (NAD) media reveal which Haemophilus species can thrive where the needed nutrients are available. Some Haemophilus strains grow only when both X and V are present, while others require V only and will grow as satellites around a source of V factor (often provided by Staphylococcus aureus colonies) but do not grow where X is the limiting factor. This satellite phenomenon is the clue. Haemophilus parainfluenzae is the organism that grows around V factor sources without needing X, so on factor V/X enriched media you’ll see colonies radiating from a V factor source rather than appearing where X is present. It’s a respiratory tract inhabitant and can be implicated in respiratory infections. By contrast, Haemophilus influenzae needs both X and V to grow and won’t show this V-only satellite pattern; Neisseria gonorrhoeae does not rely on X or V, and Legionella pneumophila requires a specialized medium with cysteine and iron, not X/V factors.