Susceptibility test methods
Most infections are treated empirically. Because of the complex requirements for these organisms, only a few specialized laboratories perform susceptibility testing. The following methods have been used for conventional testing of bacteria in the medical laboratory, and most may be used for testing Mollicutes21 - although this has proven to be time-consuming, requiring quality control strains and proper growth requirements:
- Agar dilution - used as a reference method, but not practical for most labs
- Agar disc diffusion - not useful; no correlation with minimum inhibitory concentration testing
(MICs) - Agar gradient diffusion (Etest) - comparable MIC results, although the method is not well standardized; useful for most specialized labs, and used with SP4 broth/agar
- Broth microdilution technique using a microtiter plate - the most practical and widely used method for determining MICs; labor-intensive
Note: The Centers for Disease Control and Prevention (CDC) will provide special susceptibility testing called, "Mycoplasma pneumoniae Macrolide Susceptibility Genotyping" using PCR, but only by special request.
21. Carroll KC, Pfaller MA, Karlowsky JA, Landry ML, McAdam AJ, Patel R, & Pritt, BS, eds. Manual of Clinical Microbiology. 13th edition. ASM Press. 2023.
