Which statement about mycoplasmas is true?

Which statement about mycoplasmas is true?

• A. Grow on routine nonselective culture media
• B. Resistant to penicillin
• C. Not able to survive extracellularly
• D. Easily stained using the Gram stain

Answer: (B)

Mycoplasmas lack a peptidoglycan cell wall, so antibiotics that target cell wall synthesis have no target to hit. Penicillin works by inhibiting enzymes involved in cross-linking the cell wall, but without a wall, there is nothing for penicillin to affect, making these organisms resistant. That’s why the statement about resistance to penicillin is true. In addition, they don’t grow on routine nonselective culture media and require specialized, cholesterol-containing media; they also don’t stain reliably with Gram stain because Gram staining depends on cell wall structure, which mycoplasmas do not have. They can survive outside of host cells under appropriate conditions, so the notion that they cannot survive extracellularly isn’t accurate.

Mycoplasmas lack a peptidoglycan cell wall, so antibiotics that target cell wall synthesis have no target to hit. Penicillin works by inhibiting enzymes involved in cross-linking the cell wall, but without a wall, there is nothing for penicillin to affect, making these organisms resistant. That’s why the statement about resistance to penicillin is true.

In addition, they don’t grow on routine nonselective culture media and require specialized, cholesterol-containing media; they also don’t stain reliably with Gram stain because Gram staining depends on cell wall structure, which mycoplasmas do not have. They can survive outside of host cells under appropriate conditions, so the notion that they cannot survive extracellularly isn’t accurate.