Special Test Procedures for the Mollicutes
Specific challenges are present with laboratory testing of these bacteria - routine light microscopy cannot be used to detect them, and these very tiny bacteria can pass through filters designed to remove bacteria. In addition, they do not produce visible turbidity in typical liquid growth media.
Stains
The Gram stain is not useful, as organisms without cell walls will not stain; however, the Gram stain may help to rule out other infectious bacteria. (For example, seeing a predominance of "typical" gram-negative bacteria or coccobacilli on a Gram stain of lung tissue might prompt the microbiologist to rule out Haemophilus - or any other commonly encountered pathogenic gram-negative bacteria - on subsequent culture.)
Acridine orange or a fluorescent stain may help somewhat to demonstrate organisms, but these stains are not specific (staining all types of nucleic acids). Remember, the cell wall-deficient bacteria measure approximately 0.3 x 0.8 μm, making them visible primarily with an electron microscope.
The patient's symptoms will help guide the provider to order proper test procedures for the identification of Mollicutes in clinical specimens. The Gram stain (and routine culture) reports will assist the provider by ruling out more commonly encountered pathogenic bacteria.
