Resurgence of <i>Mycoplasma pneumoniae</i> After COVID-19 Pandemic

Source: Danner MT, Binns HC, Nguyen K, et al. Resurgence of pediatric mycoplasma pneumoniae infections in southeast Texas, November 2023–June 2024. J Pediatric Infect Dis Soc. 2025;14(1):piae119; doi: 10.1093/jpids/piae119.Investigators from Baylor College of Medicine, Houston, TX, conducted a retrospective study to describe the clinical characteristics of children with Mycoplasma pneumoniae infection during a resurgence of cases beginning in late 2023. Study participants were patients <18 years old seen at sites that are part of the Texas Children’s Hospital (TCH) network. The network includes 4 hospitals and emergency departments, 12 urgent care centers, and 72 primary care clinics. The investigators tracked the monthly number and positivity rate of PCR and IgM tests for M. pneumoniae during the period January 2020 to June 2024. Using ICD-10 codes, the monthly number of patients diagnosed with upper respiratory infection (URI) and community-acquired pneumonia (CAP) also were tracked. The medical records of patients with “confirmed” M. pneumoniae disease between November 2023 and June 2024 were reviewed and demographic and clinical data abstracted. Children were classified as a confirmed case if they had a positive respiratory PCR for M. pneumoniae or a diagnosis of reactive infectious mucocutaneous eruption (RIME) and a positive IgM.During the period of January to October 2020, the monthly number of patients with CAP or URI ranged from 1.1 thousand to 16.7 thousand, with a monthly number of PCR tests for M. pneumoniae that averaged <50; there were a few scattered children with a positive PCR. However, between November 2020 and October 2023, despite increased testing, there were 0 positive M. pneumoniae PCR assays. Beginning in November 2023, the PCR positivity rate increased quickly, reaching 18.3% in June 2024, with more than 200 tests that month. During this period, the monthly number of patients diagnosed with URI and CAP ranged from 8.8 thousand to 15.7 thousand. There were a total of 152 patients with a positive PCR or serum IgM test during this period, and 81 confirmed M. pneumoniae cases, including 60 with respiratory illness and 16 with RIME. The median age of those with respiratory illness was 8.5 years; 17 (28%) were <5 years old. Of the 60 children with laboratory-confirmed M. pneumoniae respiratory illness, 41 (68%) were hospitalized, of whom 29 (71%) required supplemental oxygen, and 13 (32%) were admitted to the ICU. Among 55 patients with respiratory imaging, 24 (43%) had a focal infiltrate or consolidation. The median age of patients diagnosed with RIME was 11.5 years. Most children with RIME presented with mouth sores and conjunctivitis.The authors conclude that many children with M. pneumoniae infection during the resurgence had severe respiratory disease.Dr Brady has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.Masking and social distancing during the COVID-19 pandemic led to declines in pediatric respiratory viral infections.1 With the lifting of these non-pharmaceutical interventions after the pandemic, respiratory infections2 and diseases with infection-triggered pathogenesis, including Kawasaki disease, surged. (See AAP Grand Rounds. 2025;53[3]:27.)3 Both the current authors and the Centers for Disease Control and Prevention (CDC)’s National Syndromic Surveillance Program (NSSP) reported a reemergence of M. pneumoniae infections in children and adolescents in the United States after the COVID-19 pandemic.4The current authors reported severe respiratory disease in many children. The study, conducted at an academic medical center, required laboratory confirmation of cases and may have led to more severe presentations. Those with mild illness may not have been tested, and therefore were underestimated. The authors also called attention to the extrapulmonary manifestations of M. pneumoniae infection. A prior commentary (See AAP Grand Rounds. 2020;43[4]:41)5 reviewed skin and mucous membrane disease associated with M. pneumoniae. RIME features include involvement of 2 or 3 mucosal sites, usually mouth and eyes, and a rash that varies from vesiculobullous to targetoid to morbilliform.6In the current study, 28% of children were less than 5 years of age. When the CDC analyzed NSSP data in late 2024, they observed an increase in M. pneumoniae infections in 0–1-year-old and 2–4-year-old children.7 Although M. pneumoniae historically has been thought to affect older children and adolescents, with the availability of multiplex respiratory PCR panels, disease is now being reported in all age groups.Like influenza and respiratory syncytial virus,1 M. pneumoniae infections have resurged after the COVID-19 pandemic. Consider M. pneumoniae infection in children with CAP who do not respond to amoxicillin and in those with mucocutaneous disease.Peripheral and central nervous system disease also have been reported with M. pneumoniae infections.8 Although their pathophysiology and treatment remain, as yet, undefined, clinician awareness may increase their diagnosis in patients with unexplained acute neurologic disease.