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

Abstract

We screened 30 <i>Klebsiella pneumoniae</i> isolates from dogs and cats at a single animal hospital in Guangdong Province, China. Among them, 12 <i>K. pneumoniae</i> 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 <i>rmtB</i> were also determined by PCR mapping. The twelve 16S-RMTase gene-positive isolates were <i>rmtB</i> (11/30) and <i>armA</i> (2/30) with one isolate carrying both genes. Extended spectrum β-lactamases genes were represented by <i>bla</i>_CTX-M-55 (9/12), <i>bla</i>_CTX-M-27 (2/12) and <i>bla</i>_CTX-M-14 (1/12). The twelve 16S-RMTase containing strains were grouped into five clonal patterns and ST37 was the most prevalent sequence type. Ten <i>rmtB</i>-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. <i>rmtB</i> and <i>bla</i>_CTX-M-55 were present on the same plasmid and indicated the co-transfer of these two genes, with the <i>rmtB</i> gene showing highly relevant relationships with IS<i>26</i> and Tn<i>3</i>. Our findings suggested a high prevalence of 16S-RMTase genes in <i>K. pneumonia</i> ST37 from dogs and cats. Additional studies are needed to trace the evolutionary path of this type of resistance among the <i>K. pneumonia</i> isolates, and to determine whether they have been transferred to humans.