Mycoplasma Infection as a cause of Persistent Fever after Intravenous Immunoglobulin Treatment of Patients with Kawasaki Disease: Frequency and Clinical Impact

BACKGROUND Mycoplasma is a common cause of respiratory infections and may require differential diagnosis from Kawasaki disease (KD). In this study, we investigated the frequency and clinical manifestations of mycoplasma infection in patients with KD. MATERIALS AND METHODS Medical records of 375 in-patients admitted for treatment during the acute stage of KD, were collected, and reviewed retrospectively. Of these patients, 152 (40.5%) were also tested for recent mycoplasma infection. Patients with positive results (anti-mycoplasma IgM Ab >1:640 or cold agglutinin >1:64) were designated as the case group (n = 37, 24.3%) whereas those with negative results were designated as the control group (n = 115, 75.7%). Clinical findings of the two groups were compared. RESULTS Patients in the case group were older than those in the control group (mean age, 48.2 ± 32.1 months, vs. 31.7 ± 21.7 months; P = 0.001). There were significant differences between the case and control groups in the changes in the extremities (78.3% vs. 57.4%, respectively; P = 0.031), and in fever duration (6.5 ± 2.5 days vs. 5.4 ± 1.5 days; P = 0.047). Of the 37 patients with positive mycoplasma testing, 7 (18.9%) had persistent fever even after the symptoms and signs of systemic inflammation (acute phase of KD) had been resolved. These patients were positive for mycoplasma infection during further evaluation of persistent fever, and all of them responded to macrolide antibiotics. CONCLUSIONS We found that mycoplasma infection is somewhat related to KD. When fever persists after resolution of the acute stage of KD, mycoplasma infection may be considered as a possible cause of fever in preschool-aged children.