Research Article: Comparison of the molecular characteristics of Mycoplasma pneumoniae from children across different regions of China

Date Published: August 23, 2018

Publisher: Public Library of Science

Author(s): Guanhua Xue, Ming Li, Na Wang, Jing Zhao, Bei Wang, Zhimin Ren, Chao Yan, Chengqing Wu, Yang Liu, He Sun, Min Xu, Hongmei Sun, Daniela Flavia Hozbor.


Previous molecular characterization of Mycoplasma pneumoniae in China focused only on one or two cities. In this study, we characterized 835 samples from patients suspected to be infected with M. pneumoniae; these samples were collected in 2016 from pediatric patients from different regions of China. Multiple locus variable number tandem repeat analysis (MLVA), P1-restriction fragment length polymorphism (RFLP) analysis, and sequencing of the domain V of 23S rRNA were performed to compare genotype distribution across different locations. Two-hundred-and-thirteen samples tested positive for M. pneumoniae by PCR. P1 types were identified in 154 samples: 78.6% were type I and 21.4% were type II. Type I was the most prevalent genotype in five locations, except Nanjing where type II was the most common type (p < 0.01). Five distinct MLVA types were identified in the 172 samples. Genotype M4-5-7-2 was predominant at all locations, except Nanjing where type 3-5-6-2 was the most common (p < 0.01). Macrolide resistance-associated mutations were identified in 186 (76.3%) samples. The resistance rate differed with the location. This study showed that genotypes and macrolide resistance rate differed across China. The most prevalent genotype in China remains M4-5-7-2/P1-1. The resistance rate decreased, along with changes to the M4-5-7-2 genotype.

Partial Text

Mycoplasma pneumoniae is a common cause of respiratory infections, accounting for approximately 10–30% of all cases of community-acquired pneumonia (CAP); the prevalence increased to 50% in recent years [1]. The clinical presentation of M. pneumoniae infection widely varies, ranging from self-limiting to severe pneumonia, with extrapulmonary complications in children and adults [2].

To better understand the recent endemic outbreaks as well as the molecular characteristics of M. pneumoniae strains found in China, we collected samples from six cities across the country in 2016. In China, the total detection rate was 25.51% in 2016, which is still higher compared to that in the previous non-epidemic years [21]. This indicated a new epidemic in some areas of China, which is consistent with our previous finding that the infection rate has been increasing from late 2015 [7]. Such a trend was observed in Japan and England in 2015 [6, 8] and in Central Slovenia in 2014 [22]. It is necessary to acquire more data from other sites to survey this trend. In this study, the detection rate at different locations was similar (>27%), except in the Heilongjiang province in northeast China (11.43%). The reasons underlying the low detection rate in this area are unclear. Sample types and transport methods might be two of the reasons, because all samples collected from Heilongjiang province were swabs, and the general consensus of several studies is that sputum is the best specimen for M. pneumonia, the other specimen types varied in different studies [23–25]. Also, as distinct study protocols used by site, the transport medium and methods were different. It can also affect the detection rate. Besides, colder climate can be another reason. In fact, a previous study showed that M. pneumoniae infection positively correlated with temperature, and that the infection rate of M. pneumoniae gradually increased with the increase in the minimum temperature [26].




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