Frequency and Clinical Presentation of Mucocutaneous Disease Due to Mycoplasma pneumoniae Infection in Children With Community-Acquired Pneumonia.

Importance: The diagnosis of Mycoplasma pneumoniae infection as the cause of mucocutaneous disease is challenging because current diagnostic tests are not able to differentiate M pneumoniae infection from carriage.
Objective: To examine the frequency and clinical presentation of M pneumoniae-induced mucocutaneous disease in children with community-acquired pneumonia (CAP) using improved diagnostics.
Design, Setting, and Participants: This prospective, longitudinal cohort study included 152 children aged 3 to 18 years with CAP enrolled in a CAP study from May 1, 2016, to April 30, 2017, at the University Children's Hospital Zurich. Children were inpatients or outpatients with clinically defined CAP according to the British Thoracic Society guidelines. Data analysis was performed from July 10, 2017, to June 29, 2018.
Main Outcomes and Measures: Frequency and clinical presentation of M pneumoniae-induced mucocutaneous disease in childhood CAP. Mycoplasma pneumoniae infection was diagnosed by polymerase chain reaction (PCR) of oropharyngeal samples and confirmed with the measurement of specific peripheral blood IgM antibody-secreting cells by enzyme-linked immunospot assay to differentiate M pneumoniae-infected patients from carriers with CAP caused by other pathogens. Mucocutaneous disease was defined as any eruptive lesion that involved skin and/or mucous membranes occurring during the CAP episode.
Results: Among 152 enrolled children with CAP (median [interquartile range] age, 5.7 [4.3-8.9] years; 84 [55.3%] male), 44 (28.9%) tested positive for M pneumoniae by PCR; of these, 10 children (22.7%) developed mucocutaneous lesions. All 10 patients with mucocutaneous eruptions tested positive for specific IgM antibody-secreting cells. Skin manifestations were found in 3 cases (2.8%) of M pneumoniae PCR-negative CAP (P < .001). The spectrum of M pneumoniae-induced mucocutaneous disease included M pneumoniae-induced rash and mucositis (3 cases [6.8%]), urticaria (2 cases [4.5%]), and maculopapular skin eruptions (5 cases [11.4%]). Two patients had ocular involvement as the sole mucosal manifestation (bilateral anterior uveitis and nonpurulent conjunctivitis). Patients with M pneumoniae-induced mucocutaneous disease had longer duration of prodromal fever (median [interquartile range], 10.5 [8.3-11.8] vs 7.0 [5.5-9.5] days; P = .02) and higher C-reactive protein levels (median [interquartile range], 31 [22-59] vs 16 [7-23] mg/L; P = .04) than patients with CAP due to M pneumoniae without mucocutaneous manifestations. They were also more likely to require oxygen (5 [50%] vs 1 [5%]; P = .007), to require hospitalization (7 [70%] vs 4 [19%]; P = .01), and to develop long-term sequelae (3 [30%] vs 0; P = .03).
Conclusions and Relevance: Mucocutaneous disease occurred significantly more frequently in children with CAP due to M pneumoniae than in children with CAP of other origins. Mycoplasma pneumoniae-induced mucocutaneous disease was associated with increased systemic inflammation, morbidity, and a higher risk of long-term sequelae.