Transmission of macrolide-resistant Mycoplasma pneumoniae within a family.

Outbreaks of Mycoplasma pneumoniae have occurred in closed surroundings, including among families, university students, in military camps, and in schools, but available data on outbreaks of macrolide-resistant (MR) M. pneumoniae are limited. We encountered a family outbreak of MR M. pneumoniae pneumonia in four sisters (16, 14, 10, and 8 years of age). M. pneumoniae was isolated from all four patients, and an A-to-G transition at position 2063 in domain V of the 23S rRNA gene was identified. Although three of four patients received azithromycin, which is the first-choice antimycoplasmal agent, this agent was not effective. All isolates had an identical antibiotic susceptibility pattern. The MIC values for 14- and 15-membered macrolides, such as erythromycin, clarithromycin, and azithromycin, were >128, >128, and 64 μg/ml, respectively. On admission, all four patients were diagnosed with suspected M. pneumoniae pneumonia using the Japanese Respiratory Society (JRS) guidelines scoring system. We carried out culture and polymerase chain reaction tests for the detection of M. pneumoniae in their parents (mother, 49 years old, and father, 56 years old) four times, but no M. pneumoniae organism was detected using either test. In conclusion, MR M. pneumoniae strains can occur in outbreaks in closed surroundings, such as within families, as well as macrolide-sensitive strains. To prevent outbreaks of M. pneumoniae infection, especially MR M. pneumoniae, in closed populations, physicians should pay careful attention to the potential occurrence of infections involving MR M. pneumoniae.