Mycoplasma pneumoniae Infection in Hospitalized Children with Acute Pneumonia under the Mycoplasma Epidemic

Since October 2000, Mycoplasma pneumonia has been a recurring epidemic in Japan. To become clear the importance of Mycoplasma pneumoniae infection in children, we investigated cross-sectionally M. pneumoniae infection by serology in the hospitalized children age under seven years with acute pneumonia retrospectively reviewing pediatric patients of the four studies about lower respiratory tract infection which we had been treated during 2001 to 2003. Firstly, we found M. pneumoniae infection in 75 patients (33.8%) among a total of 222 patients with asthma exacerbation and acute pneumonia in 2001. Second, we had evaluated a total of 46 hospitalized children with acute pneumonia for M. pneumoniae infection in November 2002 and 18 patients (39.1%) were found. Thirdly, we found M. pneumoniae infection in 8 patients (34.8%) among 23 patients with respiratory syncitial virus and acute pneumonia age under two years during October 2002 to April 2003. Fourthly, we found M. pneumoniae infection in 19 patients (35.8%) among 53 patients with asthma exacerbation and acute pneumonia during January from June in 2003. Even only among the patients age under two years M. pneumoniae infection was found to be 24.3% (16/70), 27.8% (5/8), 34.8% (8/23) and 33.3% (7/21), respectively. These findings demonstrate that M. pneumoniae is common pathogen of acute pneumonia even in infants and young children under Mycoplasma epidemic. Not only typical bacteria and but also M. pneumoniae should be considered as important pathogens in the treatment of acute pneumonia in infants and young children under Mycoplasma epidemic.