Clonal Spread of 16S rRNA Methyltransferase-Producing ST37 with High Prevalence of ESBLs from Companion Animals in China.

We screened 30 isolates from dogs and cats at a single animal hospital in Guangdong Province, China. Among them, 12 strains possessed high-level resistance to amikacin and gentamicin and these were screened for 16S rRNA methyltransferase (16S-RMTase) genes. And then the genes positive isolates were detected for ESBLs (extended spectrum β-lactamases) and analyzed by pulsed-field gel electrophoresis, multilocus sequence typing, PCR-based replicon typing and plasmid analysis. The genetic profiles of were also determined by PCR mapping. The twelve 16S-RMTase gene-positive isolates were (11/30) and (2/30) with one isolate carrying both genes. Extended spectrum β-lactamases genes were represented by (9/12), (2/12) and (1/12). The twelve 16S-RMTase containing strains were grouped into five clonal patterns and ST37 was the most prevalent sequence type. Ten -bearing plasmids conjugated successfully and all belonged to IncN and IncF (F33:A-:B-) incompatibility groups. Nine of the transconjugants carried a 97 kb plasmid and the other harbored both ∼60 and ∼200 kb plasmids. and were present on the same plasmid and indicated the co-transfer of these two genes, with the gene showing highly relevant relationships with IS and Tn. Our findings suggested a high prevalence of 16S-RMTase genes in ST37 from dogs and cats. Additional studies are needed to trace the evolutionary path of this type of resistance among the isolates, and to determine whether they have been transferred to humans.