Novel strategy for typing Mycoplasma pneumoniae isolates by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry coupled with ClinProTools.

The typing of Mycoplasma pneumoniae mainly relies on the detection of nucleic acid, which is limited by the use of a single gene target, complex operation procedures, and a lengthy assay time. Here, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) coupled to ClinProTools was used to discover MALDI-TOF MS biomarker peaks and to generate a classification model based on a genetic algorithm (GA) to differentiate between type 1 and type 2 M. pneumoniae isolates. Twenty-five M. pneumoniae strains were used to construct an analysis model, and 43 Mycoplasma strains were used for validation. For the GA typing model, the cross-validation values, which reflect the ability of the model to handle variability among the test spectra and the recognition capability value, which reflects the model's ability to correctly identify its component spectra, were all 100%. This model contained 7 biomarker peaks (m/z 3,318.8, 3,215.0, 5,091.8, 5,766.8, 6,337.1, 6,431.1, and 6,979.9) used to correctly identify 31 type 1 and 7 type 2 M. pneumoniae isolates from 43 Mycoplasma strains with a sensitivity and specificity of 100%. The strain distribution map and principle component analysis based on the GA classification model also clearly showed that the type 1 and type 2 M. pneumoniae isolates can be divided into two categories based on their peptide mass fingerprints. With the obvious advantages of being rapid, highly accurate, and highly sensitive and having a low cost and high throughput, MALDI-TOF MS ClinProTools is a powerful and reliable tool for M. pneumoniae typing.