Abstract

16S rRNA methylase-mediated high-level resistance to aminoglycosides has been reported recently in clinical isolates of Gram-negative bacilli from several countries. Five (2.5%, 5/198) of 198 isolates of Proteus mirabilis from a teaching hospital in Wenzhou, China, were positive for 16S rRNA methylase genes (one for armA, four forrmtB) and highly resistant to gentamicin, amikacin and tobramycin (MICs, ≥ 256 μg/ml). One of five isolates harboring 16S rRNA methyalse genes were extended-spectrum β-lactamases (ESBL) producer. The plasmids harboring 16S rRNA methylase genes from four out of five donors were transferred into the recipients,Escherichia coli J53. Among five isolates harboring armA and rmtB, the armA gene and the rmtB genes were located on the plasmids, as determined by Southern hybridization. The present study investigated the prevalence of 16S rRNA methylase genes in clinical isolates of P. mirabilis in China for the first time.

Key words: Proteus mirabilis, 16S rRNA methylase, plasmid.