Diagnostic Methods

Clinical laboratories can provide diagnostic testing for Mycoplasma pneumoniae infections using culture, serology, or nucleic acid amplification methods (see chart below).

Unique characteristics that impact diagnostic methods

M. pneumoniae differs from other bacteria in ways that impact the methods used for diagnosis of infection:

It can pass through filters typically used to remove bacteria.
Light microscopy cannot detect it.
It does not produce visible turbidity in liquid growth media. In order to get a visual confirmation of growth, M. pneumoniae cultures require specialized media.

Diagnostic options

Currently, molecular test methods are widely used in clinical and public health laboratories. There are multiple commercially available molecular test kits cleared by the U.S. Food and Drug Administration (FDA) for the detection of M. pneumoniae. Most of these kits are used for detection of multiple respiratory pathogens, including M. pneumoniae. When additional or specialized testing is necessary, local or state public health laboratories can provide diagnostic support or forward specimens to CDC.

Advantages, disadvantages, and availability of select M. pneumoniae diagnostic methods

Advantages

Kits are commercially available
High sensitivity and specificity
Rapid time to results
Results can be obtained in time to guide treatment decisions
Strain typing and antimicrobial susceptibility determination possible (at CDC and other specialized laboratories only)

Disadvantages

Expensive
Requires specialized expertise and equipment

Test setting

Clinical services
- Real-time polymerase chain reaction (PCR) testing, including multiple FDA-approved products, at clinical laboratories¹
- State and local departments of public health may offer these diagnostic tests for the detection of M. pneumoniae
CDC
- Multiplex real-time PCR for detection of M. pneumoniae, Chlamydia pneumoniae, and Legionella species in various specimen types^2,3
- PCR-based test for macrolide susceptibility

Footnotes
¹ Acceptable specimen types and other acceptance criteria vary by testing laboratory
² Other tests performed at CDC for special investigations include: culture, P1 adhesin typing, multiple-locus variable number tandem repeat analysis (MLVA) typing, whole genome sequencing
³ FDA approved tests may be single analyte (for detection of M. pneumoniae only) or multiple analyte (for simultaneous detection of multiple respiratory pathogens).

Advantages

Recovered isolates are ideal for genotyping and antimicrobial susceptibilities testing

Disadvantages

Time-consuming and slow (may take weeks to obtain isolate)
Requires specialized expertise
High potential for false negatives
Time to results not optimal for treatment decisions

Test setting

Specialized reference laboratories only; not for routine diagnosis

Advantages

Kits are commercially available
Quantitation possible

Disadvantages

Lacks specificity
Multiple patient visits required to collect acute and convalescent paired sera specimens (time-sensitive sampling)
Time to results not optimal for treatment decisions

Test setting

Clinical services
- Sera provided to a clinical laboratory testing service for enzyme immunoassay (EIA) testing