Establishment and evaluation of standard strain of macrolide-resistant Mycoplasma pneumonia

Objective To establish standard strain of macrolide-resistant Mycoplasma pneumoniae (Mp) according to the Technical Requirements for Evaluation of National Standard Strains of Pathogenic Microorganisms(WS/T 812—2022), accelerate the progress of Mp research, and promote the construction of a national pathogenic microbial resource conservation system.

Methods The Mp standard strain was identified by 16S rDNA sequencing and specific gene PCR detection. The biological characteristics of standard strains were clarified through observation of colony morphology, genotyping, activity determination, MIC value determination and drug resistance gene detection, as well as strain stability and activity evaluation.

Results The standard strain was identified by 16S rDNA sequencing and specific gene PCR as Mp strain, and its colony morphology and various molecular biological characteristics were stable after successive generations. Minimum inhibitory concentration values of the standard strain in vitro ranged from ≥256 μg/mL, 128 μg/mL to ≥256 μg/mL and 8 μg/mL to 32 μg/mL for erythromycin, clarithromycin and azithromycin, respectively. The standard strain exhibited the 23S rDNA gene A2063G mutation at the genetic level. The standard strain can be stored stably for 12 months at −80 ℃. After thawing, the standard strain should be incubated as soon as possible, avoiding storage at 4 ℃ or room temperature and avoiding more than two freeze-thaws during use.

Conclusion This study established and evaluated standard strain of macrolide-resistant Mp（CHPC 1.13907）, providing an important material basis for Mp disease prevention and control, scientific research, drug development and vaccine development.