Epidemiology and molecular identification of mycoplasma pneumoniae associated with respiratory infections in Zhejiang province, China, 2008‐2017

Abstract Introduction Mycoplasma pneumoniae is a common cause of respiratory infections in humans. The aim of this study was to investigate the infection of Mycoplasma pneumoniae (MP) in patients with acute respiratory tract infections in Zhejiang Province from 2008 to 2017, and to provide evidence for the early diagnosis and prevention of MP pneumonia. Methods MP‐DNA was detected in nasopharyngeal swabs of patients with acute respiratory tract infection by real‐time fluorescent PCR (TaqMan probe). Statistical analysis and epidemiological investigation were carried out on the test results. Results There were 10 296 patients with acute respiratory tract infection in Zhejiang Provincial People's Hospital from 2008 to 2017, including 4387 females and 5909 males. A total of 1251 MP‐DNA–positive patients were detected, with a total positive rate of 12.2% (1251/10296). Among 1251 patients with MP infection, 571 were female positive, with an average positive rate of 13.0% (571/4387), and 680 were male positive, with a positive rate of 11.5% (680/5909). From 2008 to 2017, the positive rates were 22.8% (33 cases), 20.9% (211 cases), 20.9% (350 cases), 5.5% (70 cases), 11.7% (136 cases), 15.2% (190 cases), 7.8% (94 cases), 5.9% (62 cases), 7.8% (56 cases), and 6.0% (49 cases), respectively. Of 1251 MP‐DNA–positive patients, 1243 (99.4%) were younger than 18 years old. Conclusions Mycoplasma pneumoniae infection mainly occurs from late summer to autumn and in the age below 18 years, suggesting that early diagnosis and prevention of MP infection in adolescents should be emphasized.


| INTRODUC TI ON
Mycoplasma pneumonia (MP) is one of the most important pathogens of respiratory tract infection, and it is mainly transmitted by respiratory droplets. 1,2 It belongs to the class of flexible membranes.
Mycoplasma is the smallest pathogenic microorganism between bacteria and viruses that can live independently. It has no cell wall and is naturally resistant to antibiotics acting on the cell wall. 3 MP can cause acute, chronic respiratory infections, bronchitis, asthma, and other respiratory diseases. 4,5 It can also cause encephalitis, nephritis, myocarditis, and other extrapulmonary complications through blood dissemination or immune mechanism, especially in children's health. 6,7 In order to grasp the epidemic situation of MP infection in

| Specimen sources
Clinical data were collected from the information system of Zhejiang Provincial People's Hospital Inspection Center. This study was ap- were collected from male patients. The throat swab specimens were placed in a sterile closed tube and stored at −20°C for testing. The 10 296 patients were divided into six age groups: <18 years old, 18- 29 years old, 30-39 years old, 40-49 years old, 50-59 years old, and ≥60 years old.

| The testing of MP
The samples were washed thoroughly by adding 1 mL sterile normal Lightcycler 480 was used for amplification reaction. The reaction procedure was preheated at 93 ℃ for 2 minutes, reacted at 93℃ for 5 seconds, and reacted at 57℃ for 45 seconds, with 40 cycles. The sensitivity of the kit was 1.0 × 10 4 copies, and the linear range was 1.0 × 10 4 ~ 1.0 × 10 8 copies. If the amplification curve is S type and the CT value < 40, the sample is positive for Mycoplasma pneumoniae (+); if the CT is blank or the growth curve is not S type, it is negative for Mycoplasma pneumoniae (<500 copies).

| Statistical analysis
Categorical variables were described with counts and percentages.
The chi-square test was used in comparisons of categorical variables. Statistical analyses were performed with SPSS 17.0 software. P value <.05 was considered significant. ( Figure 1B). The monthly cases for the total study period are shown in Figure 1C. There were four peaks with the positive rate of MP over 16%, increased from late summer to autumn, and lasted for 4 to 5 months. The lowest positive rate of MP was seen as 6.27% in January.  (Table. 2). Among them, the number of patients with acute respiratory tract infection was the highest and the incidence of M. pneumoniae infection was the highest in the age group < 18 years old. The results are shown in Table 3.  in different regions. [21][22][23] The infection rate of MP in this area is at a low level, which is related to the high medical level in this area.

| D ISCUSS I ON
Judging from the degree of seasonal prevalence, this result shows that the positive cases of MP are mainly concentrated in summer, of which more positive rates are shown from July to October. In areas with moderate temperatures, outbreaks of MP infections are mainly concentrated in summer or early autumn. 24 Therefore, this area should pay more attention to the clinical concern of MP incidence from July to October, rather than the cold season with

| CON CLUS IONS
The

ACK N OWLED G M ENTS
The open-access funding was provided by the National Natural

Science Foundation of China and Zhejiang health and Health
Committee. We are grateful to Yan Zhou for the help with data collection and collation.

E TH I C A L A PPROVA L
This study was approved by the local ethics committee of Zhejiang Provincial People's Hospital. The study has been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki.

CO M PLI A N CE WITH E TH I C A L S TA N DA R DS
The authors declare that they have compliance with ethical standards.