Diagnostic Methods

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

Currently, there are multiple commercially available 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, Disadvantages, and Availability of Select M. pneumoniae Diagnostic Methods
Method Advantages Disadvantages Test Setting
Culture
  • Recovered isolates are ideal for genotyping and antimicrobial susceptibilities testing
  • 100% specificity when a positive result is obtained1
  • 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
  • Specialized reference laboratories only; not for routine diagnosis
Serology
  • Commercially available kits
  • Quantitation possible
  • 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
  • Clinical services: Sera provided to a clinical laboratory testing service for enzyme immunoassay (EIA) testing2
Molecular
  • Commercially available kits
  • High sensitivity and specificity
  • Rapid
  • Results can be obtained in time to guide treatment decisions
  • Strain typing and antimicrobial susceptibility determination possible
  • Expensive
  • Requires specialized expertise and equipment
  • Not standardized
  • Lack of clinical and comparative validation
  • Limited FDA approval
  • Clinical services: NP, OP, or sputum provided to a clinical laboratory testing service for real-time PCR testing, including multiple FDA approved products3
  • CDC: (1) Multiplex real-time PCR for detection of  M. pneumoniaeChlamydia pneumoniae, and Legionella species in NP swab, OP swab, sputum, tissue, or CSF2,4 (2) PCR-based test for macrolide susceptibility
  • Commercial/FDA approved: There are 5 assays currently available.5

1 Provided that appropriate additional procedures are used to identify the recovered isolate to species level.

2 Other tests performed at CDC for special investigations include: culture, strain typing, P1 adhesin typing, multiple-locus variable number tandem repeat analysis (MLVA) typing, whole genome sequencing.

3 State and local departments of public health may offer these diagnostic tests for the detection of M. pneumoniae.

4 FDA approved tests may be single analyte (for detection of M. pneumoniae only) or multiple analyte (for simultaneous detection of multiple respiratory pathogens).

5 Of the five currently available assays, four of them are multi-analyte and only one is single analyte (specific to M. pneumoniae).

 

NP—nasopharyngeal, OP—oropharyngeal, CSF—cerebrospinal fluid, PCR—polymerase chain reaction

 

References