[Mycoplasma pneumonia of identical twin sisters with different clinical courses depending on the treatment]

Mycoplasma pneumoniae (M. pneumoniae) pneumonia is a common disease which usually shows a good prognosis, however, it can develop a very serious state such as respiratory distress syndrome. We experienced 2 cases with M. pneumoniae pneumonia from identical twin sisters. Case 1, who was 22 years-old and was the senior sister of the twin, complained of fever and cough on August 1st, 1999. Her chest radiograph revealed consolidation in the right lung. When she was admitted to our hospital on August 11, she revealed severe hypoxemia and the titer to M. pneumoniae was markedly elevated. She was diagnosed as M. pneumoniae pneumonia with acute respiratory distress syndrome and treated with clarithromycin and methylprednisolone. Although it was necessary for her to be in the intensive care unit for 8 days, her condition gradually improved and was discharged on the 30th of September. Case 2, who was the younger sister of Case 1, complained cough and fever on August 21, 1999. Her chest radiograph showed consolidation in the left lung. She was treated by sparfloxacin because the intrafamilial infection of M. pneumoniae was most likely. The diagnosis was confirmed by the increased antibody-titer to M. pneumoniae later. There have been several reports that hyperimmune reaction may be related with the worse course of M. pneumoniae pnuemonia. However, the clinical courses of twin sisters, who should be very similar in their immune response to the same antigen, were very different from each other. The time of administration of effective antibiotics seemed to be a crucial factor to determine their courses. These results emphasized the importance of early diagnosis of the patients with M. pneumoniae pneumonia and the adequate chemotherapy to prevent developing severe respiratory failure.