Transmission of azithromycin-resistant gene, erm(T), of Gram-positive bacteria origin to Klebsiella pneumoniae.

The erm(T) gene encodes the 23 s rRNA methyltransferase and confers erythromycin resistance in Gram-positive bacteria, while has rarely been identified in Gram-negative bacteria. In this study, we identified a small IncQ1 plasmid of 6135 bp harboring the erm(T) gene in a clinical K. pneumoniae strain and confirmed the role of the erm(T) gene in mediating azithromycin resistance. This plasmid was found to be generated by incorporating the erm(T) gene from mobile elements into an IncQ1 plasmid. Our data indicated the spread of the erm(T) gene from Gram-positive bacteria to Gram-negative bacteria and the clonal spread of the ST11-KL47 type K. pneumoniae strains carrying this plasmid. Generation of this kind of multi-host plasmid will promote the dissemination of the erm(T) gene among Gram-negative bacteria and result in failures of azithromycin in treating bacterial infections.