Characterizing the epidemiology of Mycoplasma pneumoniae infections in China in 2022-2024: a nationwide cross-sectional study of over 1.6 million cases

Abstract

Mycoplasma pneumoniae (MP) is a leading cause of community-acquired pneumonia (CAP), accounting for 10-40% of cases in children. In China, the high prevalence of macrolide-resistant MP (MRMP) and recurrent MP epidemics place a significant burden on the healthcare system. Leveraging data from over 1.6 million cases, this study provides a comprehensive analysis of the epidemiological characteristics of MP across China. Seasonal patterns analysis revealed three distinct transmission zones in China. Transmission Zone 1 exhibited two annual epidemic peaks, while Zones 2 and 3 showed a single annual peak of distinct timings. Notably, winter travel to popular tourist destinations appears to influence MP infection patterns in China. Age- and sex- specific analysis indicated male newborns aged [0-1) years face a 1.67 times higher risk of MP infection compared to females. Conversely, females aged [23-38) years have a higher infection risk, likely due to their caregiving roles. The proportion of MRMP surged from 80.00% to 93.02% between July 2023 and May 2024, with a median growth rate of 10.21%. This rapid increase contrasts sharply with the modest 5.3% rise observed from 2011 to 2019, and we attribute this escalation in part to the growing prevalence of the T1-3R clade strain in China. These findings have important implications for the identification of high-risk population, place, and time for more targeted efforts of prevention and treatment. Furthermore, the rapidly increased proportion of MRMP in the 2023-2024 season raises a concerning signal regarding antibiotic use.

Keywords: China; Mycoplasma pneumoniae; age- and sex- specific; macrolide-resistant; transmission zones.

Figure 1.

Seasonal pattern and transmission zones of MP in 29 provinces. (a) K-means clustering results of epidemic trends in different provinces, Dim1 and Dim2 represent the first and second dimensions after dimensionality reduction, respectively, where Dim1 explains the largest variance (47.9%) in the data, and Dim2 explains the second-largest variance (30.8%). (b) Cluster distribution on the map of China. (c) Onset months (green dots), epidemic months (red dots), and non-epidemic months (blue dots) in different provinces and clusters. Gray lines represent the AAP trend charts for different provinces, the fitted line represents the epidemic trend for clusters 1 (red), 2 (green), and 3 (blue). Red arrows indicate epidemic peaks.

Figure 2.

Age-sex specific risk analysis of MP Infections. (a and b) Comparative analysis of ARI (a) or MP infection (b) risk between males and females. The x-axis represents age. The red bars denote the number of female cases, while the blue bars denote male cases. The green line represents the risk ratio of ARI (a) or MP (b) infection between males and females (RR-ARI-MF or RR-MP-MF). Values greater than 1 indicates higher infection risk in males, whereas less than 1 indicates higher risk in females. The red boxes mark the age range corresponding to the peak fertility years in females. (c): Three graphs illustrating positivity rates and case numbers for total cases, URTI cases, and LRTI cases. The x-axis represents age. The blue bars represent all ARIs case numbers, the red bars represent MP-positive case numbers, and the green line represents MP positivity rate. (d) Risk assessment of MP infections across different age groups. The x-axis represents different age groups, the y-axis represents the OR values, the red line represents the OR values for different age groups.

Figure 3.

Correlation between changes in Macrolide resistance rates and major epidemic clades of MP. (a) Proportion of MRMP in different provinces across the country in July 2023 and May 2024. (b) Trend chart of MRMP proportions in 29 provinces nationwide from July 2023 to May 2024. The green line represents the median resistance rate trend across 29 provinces for different months, with the upper edge of the green shaded area representing the 75th and 25th percentile of resistance rates. (c) Phylogenetic tree of MP. The two genomes marked with asterisks are strains isolated in this study. The branch information and resistance status of the genomes are annotated on the right side of the phylogenetic tree, with red indicating resistance and blue indicating susceptibility. (d) Comparison of macrolide resistance rates in different clades of MP.