A-287 Mycoplasma pneumoniae outbreak in 2023: Post pandemic resurgence of an atypical bacterial pathogen

Abstract Background Mycoplasma pnuemoniae is an atypical fastidious bacteria known to cause respiratory infections of both upper and lower tract, with a wide range of clinical presentations. M. pnuemoniae is one of the major causes of community acquired pneumonias worldwide. Almost all of the M pnuemoniae outbreak incidences have been reported in closed- community or congregate settings, such as schools, universities and colleges, and hospitals and long-term care facilities. Since the clinical symptoms of M pneumoniae overlap with other pneumonia causing pathogens, detection via multiplex PCR remains paramount for accurate and timely diagnosis to curb the infection spread. In the present study we demonstrate an unexpected increase in the detection of M. pneumoniae in the outpatient population, during 2023, as compared to the previous two years. In addition, a detailed analysis of the ICD10 diagnostic codes associated with the outbreak is also presented. Methods Respiratory samples (oropharyngeal, nasopharyngeal, sputum and EBL) summited to the HealthTrackRX laboratories were tested for the presence of M. pneumoniae and other respiratory bacterial and viral pathogens using the nanofluidic OpenArray qPCR platform (ThermoFisher, California, USA). Patient data was analyzed on the basis of age, gender and geographical location. Data was also classified in the basis of ICD10 diagnostic codes associated with the patient samples. All statistical analysis was performed using R version 3.6.0 (R Foundation for Statistical Computing). Results A total of 541,267 samples were submitted for testing at the HealthTrackRX facilities between January 1, 2021 and December 31, 2023. Only 13 samples tested positive for M. pneumoniae between 2021 (0.004%, n =3/61,498) and 2022 (0.006%, n = 10/165,423). The positivity rate of M. pneumoniae in 2023 increased to 0.19% (n = 621/314,346). The highest proportion of M. pneumoniae cases were detected from Georgia (26.8%), followed by Ohio (21.7%), Texas (8.5%) and California (6.4%). Most of the outbreak appears to be concentrated in large urban settings. Median age of the patients testing positive for M. pneumoniae was 10 (interquartile range IQR 8-18) years. Gender classification of the positive samples showed an almost equal distribution between females (49.8%) and males (50.1%). Co-infecting pathogens detected in samples positive for M. pneumoniae were similar in proportion to the M. pneumoniae negative population. The co-detected pathogens at a statistically significant difference were lower than the negative population. Survey of the ICD-10 codes submitted in conjunction with the samples suggest that the current outbreak is mostly associated with upper respiratory tract infections. Conclusions The present study shows an unprecedented increase in the detection of M. pneumoniae in the outpatient population in the United States during 2023. Our analysis suggests that this outbreak was not associated with any other bacterial or viral respiratory pathogen but appears to be case of “immunity debt” caused by the COVID19 pandemic. The outbreak of this atypical pathogen was concentrated in the pediatric population in large urban areas. Our study highlights the importance of performing continuous surveillance of respiratory pathogens, especially in the altered epidemiological landscape of the post COVID world.