Acquisition of 16S rRNA methylase gene in Pseudomonas aeruginosa

Keiko Yokoyama, Yohei Doi, Kunikazu Yamane, Hiroshi Kurokawa, Naohiro Shibata, Keigo Shibayama, Tetsuya Yagi, Haru Kato, Yoshichika Arakawa

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Abstract

Background: Bacteria develop resistance to aminoglycosides by producing aminoglycoside-modifying enzymes such as acetyltransferase, phosphorylase, and adenyltransferase. These enzymes, however, cannot confer consistent resistance to various aminoglycosides because of their substrate specificity. Notwithstanding, a Pseudomonas aeruginosa strain AR-2 showing high-level resistance (minimum inhibitory concentration >1024 mg/L) to various aminoglycosides was isolated clinically. We aimed to clone and characterise the genetic determinant of this resistance. Methods: We used conventional methods for DNA manipulation, susceptibility testing, and gene analyses to clone and characterise the genetic determinant of the resistance seen. PCR detection of the gene was also done on a stock of P aeruginosa strains that were isolated clinically since 1997. Findings: An aminoglycoside-resistance gene, designated rmtA, was identified in P aeruginosa AR-2. The Escherichia coli transformant and transconjugant harbouring the rmtA gene showed very high-level resistance to various aminoglycosides, including amikacin, tobramycin, isepamicin, arbekacin, kanamycin, and gentamicin. The 756-bp nucleotide rmtA gene encoded a protein, RmtA. This protein showed considerable similarity to the 16S rRNA methylases of aminoglycoside-producing actinomycetes, which protect bacterial 16S rRNA from intrinsic aminoglycosides by methylation. Incorporation of radiolabelled methyl groups into the 30S ribosome was detected in the presence of RmtA. Of 1113 clinically isolated P aeruginosa strains, nine carried the rmtA gene, as shown by PCR analyses. Interpretation: Our findings strongly suggest intergeneric lateral gene transfer of 16S rRNA methylase gene from some aminoglycoside-producing microorganisms to P aeruginosa. Further dissemination of the rmtA gene in nosocomial bacteria could be a matter of concern in the future.

Original languageEnglish
Pages (from-to)1888-1893
Number of pages6
JournalLancet
Volume362
Issue number9399
DOIs
Publication statusPublished - 06-12-2003
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Medicine(all)

Cite this

Yokoyama, K., Doi, Y., Yamane, K., Kurokawa, H., Shibata, N., Shibayama, K., Yagi, T., Kato, H., & Arakawa, Y. (2003). Acquisition of 16S rRNA methylase gene in Pseudomonas aeruginosa. Lancet, 362(9399), 1888-1893. https://doi.org/10.1016/S0140-6736(03)14959-8