Community-acquired macrolide-resistant Mycoplasma pneumoniae pneumonia in patients more than 18 years of age.

A macrolide-resistant Mycoplasma pneumoniae strain was isolated from two patients with community-acquired pneumonia. The pneumonia severity score of both patients was mild, and rapid clinical improvement was seen after administration of fluoroquinolone. Clinical features of macrolide-resistant M. pneumoniae pneumonia were identical to those of macrolide-sensitive M. pneumoniae pneumonia. An A-to-G transition at position 2063 and 2064, respectively, in domain V of the 23S rRNA gene was identified. The minimum inhibitory concentration of erythromycin of these isolates was greatly elevated. In Japan, macrolide-resistant M. pneumoniae infections are common in pediatric patients but not in adults. However, physicians should pay attention to macrolide-resistant M. pneumoniae not only in children but also in adults.