Prevalence of Mycoplasma IgM in children with lower respiratory tract illness

Background:  Few data are available for the recent occurrence of Mycoplasma infections in children in Japan. The purpose of the present study was therefore to identify the prevalence of Mycoplasma infections in children in Japan.
Methods:  IgM antibodies to M. pneumoniae were prospectively determined using the Meridian ImmunoCard Mycoplasma test in hospitalized patients with lower respiratory tract infections between January 2004 and June 2007. A total of 858 hospitalized patients aged 0–15 years (445 male, 413 female), diagnosed as having acute pneumonia or bronchitis, were enrolled. The number of patients with pneumonia or bronchitis was 331 (male/female, 167/164) and 527 (male/female/ 278/249), respectively. Two hundred and five of the 858 patients (23.9%) were ImmunoCard positive. Of the 205 patients, 121 children and 84 children were diagnosed as having pneumonia and bronchitis, respectively. One hundred and forty-three of the 727 patients (19.7%) <5 years of age were ImmunoCard test positive.
Conclusions:  M. pneumoniae infection is not rare in children aged <5 years in Japan.