During the COVID-19 pandemic, a significant decline in Mycoplasma pneumoniae was observed; however, M. pneumoniae re-emerged globally in 2023. Here, we describe a current outbreak of M. pneumoniae infections in the United States (US). More than 287 million patient records from all 50 states in the US were reviewed to identify patients with a M. pneumoniae diagnosis between 1 January 2017 and 30 September 2024. A c-chart was created by calculating the mean and standard error (SE) of cases during the pre-COVID-19 pandemic period, with the upper control limit (UCL) set at 3 SE above the mean. The presence of an outbreak was defined as counts above the UCL. Cumulative excess cases were used to estimate the magnitude of the outbreak, and the fold increase was calculated. A US outbreak of M. pneumoniae began at the end of 2023, resulting in 9708 excess cases corresponding to a 9.0-fold increase over the baseline UCL. The outbreak is ongoing, affects both children and adults, and includes patients with M. pneumoniae community-acquired pneumonia requiring hospitalization. This US outbreak of M. pneumoniae has significant implications for the management of patients with respiratory infections during the current pneumonia season.

Detection of viral RNA in nasopharyngeal (NP) samples by reverse transcription polymerase chain reaction (RT-PCR) is the standard diagnostic test for influenza or respiratory syncytial virus (RSV) in hospitalized patients with community-acquired pneumonia (CAP). This study compared the sensitivity of RT-PCR using NP swab, saliva, and sputum samples for the diagnosis of CAP due to influenza or RSV. A total of 60 patients were evaluated, of which 40 (67%) had influenza CAP, 19 (32%) had RSV CAP, and one patient (1%) had both RSV and influenza CAP. RT-PCR on NP swab, saliva, and sputum samples was performed using the Luminex ARIES platform. In patients with influenza CAP, the sensitivity was 34% for NP swabs, 68% for saliva, and 71% for sputum. In patients with RSV CAP, the sensitivity was 60% for NP swabs, 75% for saliva, and 85% for sputum. RT-PCR of nasopharyngeal swab samples was associated with a significant number of false negative results. A negative NP swab RT-PCR test should not be used to rule out CAP due to influenza or RSV. Saliva and sputum samples should be considered when performing a microbiological work-up in patients with suspected influenza or RSV CAP.

During the COVID-19 pandemic, a significant decline in Mycoplasma pneumoniae was observed. However, M. pneumoniae reemerged globally in 2023. Here we describe a current outbreak of M. pneumoniae infections in the United States (US). More than 287 million patient records from all 50 states in the US were reviewed to identify patients with a M. pneumoniae diagnosis between January 1, 2017, and September 30, 2024. A C-chart was created by calculating the mean and standard error (SE) of cases during the pre-COVID-19 pandemic period, with the upper control limit (UCL) set at 3 SE above the mean. The presence of an outbreak was defined as counts above the UCL. Cumulative excess cases were used to estimate the magnitude of the outbreak, and the fold increase was calculated. A US outbreak of M. pneumoniae began at the end of 2023, resulting in 9,708 excess cases corresponding to a 9.0-fold increase over the baseline UCL. The outbreak is ongoing and is affecting both children and adults, including patients with M. pneumoniae community-acquired pneumonia requiring hospitalization. The current US outbreak of M. pneumoniae has significant implications for the management of patients with respiratory infections during the current pneumonia season.