What is the recommended medium for recovery of Mycoplasma pneumoniae from clinical specimens?

• A. Charcoal yeast extract medium
• B. Fletcher semisolid medium
• C. Middlebrook
• D. SP4 agar

Answer: (D)

Growth of Mycoplasma pneumoniae requires a rich, cholesterol-containing medium because these organisms lack a cell wall and need sterols for membrane stability. SP4 agar is a specialized medium formulated to support the growth of Mycoplasma species, including M. pneumoniae, by providing the necessary nutrients and cholesterol (sterol source) along with amino acids and serum components. In clinical specimens, this medium enables recovery and visible colony formation, which often presents as tiny colonies with a fried-egg appearance after a prolonged incubation in a CO2-enriched environment. Other media listed are used for different organisms (charcoal yeast extract for Legionella; Middlebrook for mycobacteria) or are older alternatives, but SP4 agar is the standard choice for recovering M. pneumoniae from clinical samples.