Fig. 1

Mass spectrum results showing the sensitivity of the detection of Mycoplasma pneumoniae. A negative control, B–E M pneumoniae strain diluted to 10, 100, 1000, and 10,000 copies/μl, respectively. The arrow on the left side of the spectrum results indicates the position of the extension primer peak, the arrow on the right side indicates the position of the extension product, and the peak at approximate 5235 Da is the non-extended primer of HCoV. When concentrations of the negative control and pathogen were 10 copies/μl, there was only an extension primer peak and no extension product peak. At plasmid concentrations of 100, 1000, and 10,000 copies/μl, extension product peaks appeared, and the extension primer peaks became smaller or absent due to consumption. Thus, the detection sensitivity for M. pneumoniae was 100 copies/μl