Which test is used to screen for Mycoplasma pneumoniae isolates?

Which test is used to screen for Mycoplasma pneumoniae isolates?

• A. Lysis of red blood cells
• B. Acid-fast stain
• C. Gram stain
• D. Catalase test

Answer: (A)

Mycoplasma pneumoniae is unique because it lacks a cell wall, so it doesn’t stain well with Gram stain and isn’t acid-fast. A classic way to screen for and identify this organism in culture is the hemadsorption test: red blood cells are added to colonies grown on specialized, cholesterol-containing media (like Eaton’s agar), and if Mycoplasma pneumoniae is present the red blood cells adhere to the surface of the colonies. This RBC adsorption is a characteristic clue for the organism and helps distinguish it from others. Lysis of red blood cells isn’t a reliable screening feature for this pathogen, and acid-fast staining or Gram staining aren’t useful for detecting Mycoplasma because of its lack of a cell wall. Catalase testing isn’t diagnostic for Mycoplasma pneumoniae either. For confirmation, serology or PCR can be used alongside the culture-based hemadsorption observation.

Mycoplasma pneumoniae is unique because it lacks a cell wall, so it doesn’t stain well with Gram stain and isn’t acid-fast. A classic way to screen for and identify this organism in culture is the hemadsorption test: red blood cells are added to colonies grown on specialized, cholesterol-containing media (like Eaton’s agar), and if Mycoplasma pneumoniae is present the red blood cells adhere to the surface of the colonies. This RBC adsorption is a characteristic clue for the organism and helps distinguish it from others.

Lysis of red blood cells isn’t a reliable screening feature for this pathogen, and acid-fast staining or Gram staining aren’t useful for detecting Mycoplasma because of its lack of a cell wall. Catalase testing isn’t diagnostic for Mycoplasma pneumoniae either. For confirmation, serology or PCR can be used alongside the culture-based hemadsorption observation.