An outbreak of Mycoplasma pneumoniae infections in Louisville, KY: Clinical practice and public health implications.

Background After the COVID-19 pandemic, a re-emerging of Mycoplasma pneumoniae infections has been reported globally. The objective of this study is to define the epidemiology of M. pneumoniae in the city of Louisville. Methods All cases of M. pneumoniae infection since January 1, 2017 until December 31, 2024 were evaluated. A baseline cohort from January 1, 2017 to March 31, 2020 was used to develop the expected upper control limits for detecting infection. Infections were aggregated by annual quarter and depicted in c-charts. Results An outbreak was identified starting in the fourth quarter of 2023, when the number of infections due to M. pneumoniae exceeded the upper control limit set by the baseline cohort. The current outbreak has affected 925 patients with M. pneumonaie infection. Conclusions We documented a current outbreak of M. pneumoniae infections in Louisville, starting in the fourth quarter of 2023. This outbreak of respiratory infections due to an atypical pathogen has implications for clinicians and public health professionals. This outbreak highlights the importance of active surveillance of respiratory pathogens.