Study of Exchange Phenomenon of Mycoplasma pneumoniae in Children from 1997-2002

Purpose:Mycoplasma pneumoniae(M. pneumoniae) is classified into two groups(I and II) by difference of DNA sequences in P1 protein. Between these two groups, there are some different immune responses and disease severity. M. pneumoniae pneumonia have epidemic outbreaks occurring every three to seven years and these outbreaks are related with rising of either group I or II. We studied cases of M. pneumoniae pneumonia during the past six years(November 1996-October 2002), to evaluate the prevalence and yearly distribution of each group. Methods:We enrolled 504 patients out of 547 patients, who were admitted to the Department of Pediatrics, Sung-Ae and Kwangmyung Sung-Ae General Hospital from November 1996 to October 2002. They were diagnosed as M. pneumoniae pneumonia by clinical characteristics and indirect particle agglutination test of M. pneumoniae. To classify into two groups, the group specific polymerase chain reaction amplification were performed using specific oligonucleotide primers designed for P1 gene genotyping. Results:Group I(91.7%) occured more frequently than group II(8.3%) during the study period. There were outbreaks of M. pneumoniae pneumonia in 1997 and 2000, which showed epidemics of M. pneumoniae pneumonia were occuring every three or four years, but there was no exchange phenomenon between the two groups. Conclusion:Group I was more prevalent than group II with a three years cycle of epidemic outbreak from 1997 to 2002 in Korea. But, six years of research is a relatively short time to compare immune responses, disease severity and exchange phenomenon between the two groups. Further follow-up study will be needed for the epidemiologic and clinical studies of M. pneumoniae in Korea. (Korean J Pediatr 2004;47:24-30)