Recent data regarding the clinical epidemiologic characteristics of Mycoplasma pneumoniae pneumonia in Korean adults are insufficient. This study was conducted in order to compare epidemics in different ages and to identify the clinical characteristics in adults.

We investigated patients who visited Korea University Guro Hospital from January to December 2011 due to community acquired pneumonia and underwent mycoplasma antibody tests. M. pneumoniae pneumonia was diagnosed if mycoplasma antibody titer was ≥1:320 at any time, seroconversion or 4-fold rise was seen at convalescent phase. Patients under the age of 19 were classified as child and adolescent, otherwise adult. We investigated the number of monthly cases in all patients and reviewed the medical records of adult patients.

A total of 249 young patients aged ≤18 years and 29 adults were diagnosed with M. pneumoniae pneumonia. Among young patients, 75.5% were concentrated in the 0-6 years age group and 58.6% of adults belonged to the 26-40 years age group. The number of young patients began to increase in July and continued to increase in December, while the number of adult patients began to increase in August and occurred continuously until December. The correlation coefficient of the epidemic trend between the two groups was 0.682 (P=0.015). Median age of adult patients was 33.3 years. Fever was observed in all patients and 25 patients (86.2%) complained of purulent sputum. The average white blood cell count was 7,066/mm³. The average values for aspartate aminotransferase, alanine aminotransferase, creatinine, and sodium were within the normal range. In chest X-ray study, ipsilateral lower patchy consolidation was found in 24 patients (82.8%). Twenty one adult patients (72.4%) were hospitalized. The mean duration of hospitalization was 7.3 days. Twenty three patients (79.3%) were initially treated with combinations of third generation cephalosporin and macrolide. Among them, five patients (17.2%) showed poor responses. Six cases (20.7%) were initially treated with quinolone, and treatment was maintained until the end without changing antibiotics. Development of cryptogenic organizing pneumonia occurred in one case and there was no occurrence of death.

When M. pneumoniae pneumonia is epidemic among children and adolescents, it should also be suspected in adult patients with community-acquired pneumonia. Some patients showed poor responses to macrolide. Overall, it appears that additional studies are needed for evaluation of the effectiveness of macrolide in treatment of M. pneumoniae pneumonia in adults.