Loop-mediated isothermal amplification assay for 16S rRNA methylase genes in Gram-negative bacteria.

Abstract

Using the loop-mediated isothermal amplification (LAMP) method, we developed a rapid assay for detection of 16S rRNA methylase genes (rmtA, rmtB, and armA), and investigated 16S rRNA methylase-producing strains among clinical isolates. Primer Explorer V3 software was used to design the LAMP primers. LAMP primers were prepared for each gene, including two outer primers (F3 and B3), two inner primers (FIP and BIP), and two loop primers (LF and LB). Detection was performed with the Loopamp DNA amplification kit. For all three genes (rmtA, rmtB, and armA), 10(2) copies/tube could be detected with a reaction time of 60 min. When nine bacterial species (65 strains saved in National Institute of Infectious Diseases) were tested, which had been confirmed to possess rmtA, rmtB, or armA by PCR and DNA sequencing, the genes were detected correctly in these bacteria with no false negative or false positive results. Among 8447 clinical isolates isolated at 36 medical institutions, the LAMP method was conducted for 191 strains that were resistant to aminoglycosides based on the results of antimicrobial susceptibility tests. Eight strains were found to produce 16S rRNA methylase (0.09%), with rmtB being identified in three strains (0.06%) of 4929 isolates of Enterobacteriaceae, rmtA in three strains (0.10%) of 3284 isolates of Pseudomonas aeruginosa, and armA in two strains (0.85%) of 234 isolates of Acinetobacter spp. At present, the incidence of strains possessing 16S rRNA methylase genes is very low in Japan. However, when Gram-negative bacteria showing high resistance to aminoglycosides are isolated by clinical laboratories, it seems very important to investigate the status of 16S rRNA methylase gene-harboring bacilli and monitor their trends among Japanese clinical settings.

• Authors: Mitsuaki Nagasawa, Mitsuo Kaku, Kazunari Kamachi, Keigo Shibayama, Yoshichika Arakawa, Keizo Yamaguchi, Yoshikazu Ishii
• Journal: Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy (J Infect Chemother) Vol. 20 Issue 10 Pg. 635-8 (Oct 2014) ISSN: 1437-7780 [Electronic] Netherlands
• PMID: 25179393 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Chemical References

• Aminoglycosides
• DNA Primers
• DNA, Bacterial
• RNA, Ribosomal, 16S
• Methyltransferases

Topics

• Acinetobacter (genetics)
• Aminoglycosides (pharmacology)
• DNA Primers
• DNA, Bacterial (analysis)
• Drug Resistance, Bacterial (genetics)
• Enterobacteriaceae (genetics)
• Gram-Negative Bacteria (drug effects, genetics)
• Gram-Negative Bacterial Infections (microbiology)
• Humans
• Methyltransferases (genetics)
• Nucleic Acid Amplification Techniques (methods)
• Pseudomonas aeruginosa (genetics)
• RNA, Ribosomal, 16S (genetics)
• Sensitivity and Specificity
• Time Factors