Results
A total of 1237 specimens from children with CAP in the year of 2020 were tested. We detected M. pneumoniae by real-time qPCR in 121 (9.8%) of all specimens. Fig. 1 shows the testing results in different months of the year. The number of M. pneumoniae -positive specimens fluctuated from 1 to 49 in each month. Of allM.pneumoniae -positive strains,116 (96%) were macrolide resistant by detecting point-mutations in 23S rRNA. All of 23S rRNA mutations were A2063G, one of them was heterozygous mutation.
All of positive specimens, including 116 macrolide resistant M. pneumoniae (MRMP) and 5 macrolide-susceptible M. pneumoniae(MSMP), were further analyzed by MLVA typing. However, there was 11 MRMP and 1 MSMP samples unable to fulfill MLVA typing, and it was probably because the levels of M.pneumoniae nucleic acid were too low. Finally they were excluded in analysis.
As a result, the majority (60/105, 57%) of strains in the MRMP group could be matched to MLVA type 4-5-7-2 by the 4-loci typing scheme,45 strains in the MRMP group were 3-4-6-2. On the other hand, all of strains in the MSMP group were 3-4-6-2(Table 2). The independence test showed that MLVA types had no relationship with macrolide-resistant mutation (P>0.05).The distribution of MLVA types among MRMP and MSMP is showed in Fig 2.