Characterization of macrolide resistance in Mycoplasma pneumoniae isolated from children in Shanghai, China.

One hundred Mycoplasma pneumoniae strains were isolated from pediatric patients from March 2008 to July 2009. Of 100 isolates, 90 (90%) were resistant to erythromycin (MICs >128 microg/mL for 88 strains and 64 microg/mL for 2 strains), azithromycin, and clarithromycin. Fluoroquinolones and tetracyclines maintain good activities against clinical M. pneumoniae isolates. Of 90 macrolide-resistant M. pneumoniae strains, 88 (98%) harbored an A-to-G transition mutation at position 2063 in 23S rRNA genes, and the remaining 2 showed either A2064G or A2063T mutation; the latter point mutation is newly discovered and reported. Ninety-three (93%) clinical isolates were classified into the P1 gene restriction fragment length polymorphism (RFLP) type I, and 7 (7%) were type II.