Abstract: Background It is difficult to dignose mycoplasma pneumoniae encephalitis (MPE) and the available medicine is limited. Objective To summarize the clinical features, diagnosis and treatment of children diagnosed with MPE. DesignCase series report. Methods The clinical manifestations, laboratory examination and imaging changes, treatment and outcomes in consecutively hospitalized patients diagnosed with MPE from January 2017 to December 2019 were retrospectively analyzed. Main outcome measures Recurrence or relapse. Results A total of 4 patients were all boys without any other underlying diseases. All of them mainly presented with fever and nervous system abnormality, 2 of whom had respiratory symptoms and 1 developed gastrointestinal symptoms. Serum mycoplasma pneumoniae (MP) IgM antibody detection was positive and other common pathogens were negative in all cases. As to cerebrospinal fluid test, 3 cases showed increased nucleated cell number, 1 case had weak positive protein and 1 case presented increased cerebrospinal fluid immunoglobulin. Multiple lesions in cranial magnetic resonance imaging (MRI) and abnormal electroencephalographic (EEG) were showed in all patients. Only one patient's condition was gradually worsened after 2 times of methylprednisolone and three times of intravenous immunoglobulin (IVIG) treatment, but the following condition was improved after three weeks of levofloxacin therapy combined with methylprednisolone pulse treatment and maintenance therapy. The other three patients' conditions were improved after receiving three weeks of levofloxacin therapy combined with IVIG pulse treatment and glucocorticoid. Follow-up after discharge showed that all patients' conditions continued to improve without recurrence or relapse. Conclusion The diagnosis of MPE can be established based on positive serological MP-IgM and the clinical manifestations and imaging features of encephalitis after other common pathogens were excluded. Levofloxacin combined with glucocorticoid and gamma globulin can achieve obvious efficacy and improve the prognosis of MPE.

Key words: Children, Mycoplasma pneumoniae encephalitis, Levofloxacin, Immune globulin, Methanone nylon