Mycoplasma pneumoniae triggers pneumonia epidemic in autumn and winter in Beijing: a multicentre, population-based epidemiological study between 2015 and 2020

Abstract

ABSTRACTThe objective of this paper is to explore the characteristics of Mycoplasma pneumoniae (MP) epidemics in Beijing, China. Patients with acute respiratory tract infection (ARTI) were enrolled from 35 sentinel hospitals in Beijing, 2015-2020. Their medical records were reviewed and respiratory specimens were collected for assay for nucleic acids of 24 respiratory pathogens, including MP. The genotypes of MP were analysed using a real-time PCR method. The domain V of 23s rRNA gene was sequenced to identify macrolide-resistant mutations. A total of 41,677 specimens of ARTI patients were included, with an MP positive rate of 6.16%. MP prevalence mainly occurred between August and January, and peaked in October. The increase in the MP detection rate was coincident with the elevation of the reported number of patients with pneumonia in the 35 sentinel hospitals. One or more respiratory pathogens were co-detected in 27.1% of the MP-positive patients. Type 1 MP remained predominant, and the macrolide-resistant rate of MP had exceeded over 90%. A2063G mutation accounted for 99.0% of macrolide-resistant MP infections. MP epidemic in Beijing mainly occurred between August and January with a remarkable high macrolide-resistant rate. MP is one of the important contributors to the pneumonia epidemic in autumn and winter in Beijing.

Keywords: Mycoplasma pneumoniae; Mycoplasma pneumoniae pneumonia; acute respiratory tract infection; macrolide-resistant Mycoplasma pneumoniae; surveillance.

Figure 1.

MP prevalence among all-aged patients with acute respiratory tract infection in Beijing, China, from January 1, 2015, to December 31, 2020. (A) The number of patients with acute respiratory tract infection and MP positive rates by month. (B) Average percentage of positive detections for MP among all aged patients with acute respiratory tract infections per month. (C) MP season duration and peak by year. The grey bars (panels A and B) denote the number of MP-negative cases. The blue bars (panels A and B) represent the MP-positive cases. The solid lines (panels A and B) indicate the percentage of MP-positive cases among the total cases included in this study, where the orange part represents the non-epidemic period and the yellow part represents the popular period. The dash lines (panels A and B) denote the threshold of MP-positive rate (5%) assigned in this study. The blue horizontal lines (panel C) indicate the MP season duration, and the black dot represents the MP epidemic peak. MP, Mycoplasma pneumoniae.

Figure 2.

MP prevalence among patients with acute respiratory tract infections (ARTI) in Beijing, China, from January 1, 2015, to December 31, 2020, by age, or by sex, or by severity of illness. (A) MP infections among patients with ARTI by age. The light grey bars denote the total number of ARTI cases included in this study. The dark black line indicates the percentage of MP-positive cases among total cases. (B) Analysis of nonlinear influence of age on the risk of MP infection (P < 0.001). (C) Analysis of nonlinear influence of age on the risk of MP infection among patients with SCAP. (D) MP infections among patients with ARTI by severity of illness. The rug plot (panel B and C) along the x-axis shows the observed values; grey shading indicates 95% CIs. The dark black bars (panel D) indicate the percentage of MP-positive cases among total cases.

Figure 3.

Co-detected pattern and interactions of MP and other respiratory pathogens in patients with acute respiratory tract infection in Beijing, China, from January 1, 2015, to December 31, 2020. (A) Co-detected pattern of MP and other respiratory pathogens. Co-detected rates were calculated pairwise. A total of 30 indicators were included (15 respiratory virus-related, 13 respiratory bacteria-related and MP, Chlamydia pneumoniae; except influenza virus A). For pathogens “X” and “Y”, the numerator was the number of patients in whom “X” and “Y” were co-detected, and the denominator was the total number of patients who were both tested “X” and “Y”. Bigger size and darker colour of the circles indicate higher co-detected rates between two pathogens. (B) The interactions among MP and other pathogens were estimated by host-scale logistic regressions. Positive interactions with two-sided P-value <0.05 are denoted with orange bars and the negative interactions with two-sided P-value <0.05 are denoted with blue bars. The P values were not adjusted for multiple comparisons. The length of the coloured bars and the adjacent number indicate the odds ratio (OR) of the interaction. The interaction was determined as significant both without adjusting for multiple pathogens and with adjusting for multiple pathogens. Influenza virus AH1N1 2009 pandemic and AH3N2 (AH1N1, AH3N2), influenza virus B (FLU B), respiratory syncytial virus (RSV), parainfluenza virus 1, 2, 3, and 4 (PIV 1, 2, 3, 4), adenovirus (AdV), human rhinovirus (HRV), human metapneumovirus (HMPV), human coronavirus 229E/NL63, OC43/HKU1 (CoV 229E/NL63, OC43/HKU1), human bocavirus (HBoV), human enterovirus (EV).

Figure 4.

The reported numbers of patients with upper respiratory tract infection (URTI) or community-acquired pneumonia (CAP) presented to 35 sentinel hospitals in Beijing, China, from January 1, 2017, to December 31, 2020; the positive detection rates of each of 11 respiratory pathogens, including MP, by month. (A) The reported numbers of patients with URTI by month. (B) The positive rates of MP and influenza virus among patients with URTI by month. (C) The positive rates of nine respiratory viruses among patients with URTI by month. (D) The reported numbers of patients with CAP by month. (E) The positive rates of MP and CP among patients with CAP by month. (F) The positive rates of nine respiratory viruses among patients with CAP by month. (G) The pathogenic spectrum of CAPs in pneumonia epidemic season. The red arrow (panels A and D) denotes the time point of implementation of public health measures against the COVID-19 pandemic in Beijing. URTI, upper respiratory tract infection; CAP, community-acquired pneumonia.

Figure 5.

Time trend of the prevalence of two genotypes of MP, Beijing, China, 2008–2020. The grey bars denote the proportion of type 1 MP among total MP-positive cases, and the red bars denote type 2. The data on the prevalence of the two genotypes between 2008 and 2018, based on previous studies[1–3]. The black horizontal dash represents the threshold (20%) of the proportion of type 2.

Figure 6.

Time trend of MRMP prevalence in Beijing, China, 2008–2020. The grey bars indicate the overall proportion of MRMP among total MP-positive patients. The black line denotes the MRMP proportion among patients infected with type 1 MP, and the red line denotes that in patients infected by type 2 MP. The data on the MRMP prevalence in Beijing between 2008 and 2018 were retrieved from multiple previous studies[1–3]. MRMP, macrolide-resistant Mycoplasma pneumoniae.