Nested PCR-linked capillary electrophoresis and single-strand conformation polymorphisms for detection of macrolide-resistant Mycoplasma pneumoniae in Beijing, China.

Mycoplasma pneumoniae is usually susceptible to macrolides, but macrolide-resistant strains have been found frequently in recent years. Mutations in domain V of the 23S rRNA gene of M. pneumoniae interfere with the binding of macrolides to rRNA and mediate macrolide resistance. In this study, we developed a rapid and inexpensive method that combines nested PCR (nPCR), single-strand conformation polymorphisms (SSCPs), and capillary electrophoresis (CE) to detect macrolide-resistant mutants directly from throat swabs. nPCR was used to specifically amplify M. pneumoniae 23S rRNA gene fragments containing mutations, and amplicons were analyzed by CE-SSCP for macrolide resistance mutations, with results confirmed by sequencing. From January to December 2009, 665 throat swabs were collected in Beijing, China, yielding 110 samples that tested positive for M. pneumoniae by nPCR and serological testing. We randomly selected 64 positive throat swabs for CE-SSCP analysis. The A2063G mutation was found in 57 samples, and a coexisting T2611C mutation was identified in 1 sample. An A2063T mutation was identified in 1 sample. The total mutation rate was 91%. All mutant samples identified by nPCR-CE-SSCP were sequenced. The nPCR-CE-SSCP method could identify macrolide-resistant mutants directly from clinical samples. This is the first report of an nPCR-CE-SSCP assay for the detection of dominant mutations that confer macrolide resistance on M. pneumoniae. This approach would allow clinicians to choose appropriate therapy rapidly and could be used as a screening method for genetic mutations related to antibiotic resistance.