Mycoplasma pneumoniae pneumonia has been to be developed frequently in school age children and adolescence and hard to see under 3 year-old children. But it seems to be increased in number of patients with Mycoplasma pneumoniae pneumonia under 3-year old in clinical practice in these .days. We have aimed to examine the characteristics of clinical findings of Mycoplasma pneumonia under 3 year-old children.

We had performed retrospective review of medical records of 30 patients with Mycoplasmal pneumonia under 3-year old children who admitted to Department of Pediatrics, Kyunghee University Hospital from Jan. 1994 to Dec. 1997. The diagnostic criteriae was Cold agglutinin titer>1:64 or Mycoplasma antibody titer>1:80.

Mycoplasmal pneumonia was 30 out of 235 cases(12.7%) of total pneumonia under 3 year old children. Male female ratio was 1.3 : 1 and age distributions were 0~1y : 0, 1~2y : 8, 2~3y : 22 cases. Clinical symptoms and signs were cough(100.0%), sputum(83.3%), fever(80.0%) rhinorrhea(33.3%), vomiting(33.3%), moist rale(86.7%), decreased breathing sound(26.7%), wheezing(20.0%), and pharyngeal injection(30.0%). Thirteen out of 30 cases(43.3%) had unilateral infiltration, 10 cases(33.4%) had bilateral infiltration, 1 case(3.3%) had pleural effusion, and 6 cases(20.0%) had negative findings on chest radiography and there was no cases of atelectasis. On laboratory findings, 6 out of 30 cases(20.0%) had leukocytosis, 1 case(3.3%) had neutrophilia, 10 cases(30.0%) had eosinophilia, 17 cases(56.7%) had increased ESR, and 18 cases(60.6%) had positive CRP. Positive cold agglutinin titers(>1 : 64) were 19 cases(63.3%), and positive mycoplasma antibody(M-ab) titers(>1 : 80) were 27 cases(93.3%). Mycoplasma antibody test was more valuable than cold agglutinin test for the diagnosis of Mycoplasmal pneumonia and there was no correlation between cold agglutinin titer and mycoplasma antibody titer. Mycoplasma-polymerase chain reaction(M-PCR) was done with 13 cases, 12 out of 13 cases(92.3%) were positive. M-PCR test was valuable to the diagnosis of Mycoplasmal pneumonia but it will be needed to further study for their clinical application. Among 30 cases, 5 cases(16.7%) had complications, 3 cases(10.0%) had skin rash, 1 case(3.3%) had pleural effusion, 1 case(3.3%) had arthralgia, but all complications were mild and recovered without residual sequelae.

The occurrence of Mycoplasmal pneumonia under 3 year-old children was not rare from this study. Clinical characteristics of Mycoplasmal pneumonia under 3-year old were normal radiologic findings in many cases, low complication rate, mild clinical course, and tend to rapid recovery compared with general manifestations of Mycoplasmal infectionsin children and adolescence. There were likely to be missed patients with Mycoplasmal pneumonia which did not diagnose by conventional serologic tests that had low sensitivity and specificity. We have to pay attention to the Mycoplasmal infection of the young children with pneumonia during epidemic periods of Mycoplasmal infection.