This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Zong, Z.
Right arrow Articles by Iredell, J. R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Zong, Z.
Right arrow Articles by Iredell, J. R.

 Previous Article  |  Next Article 

Antimicrobial Agents and Chemotherapy, February 2008, p. 794-795, Vol. 52, No. 2
0066-4804/08/$08.00+0     doi:10.1128/AAC.01399-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

LETTER TO THE EDITOR

RmtC 16S rRNA Methyltransferase in Australia{triangledown}


arrow
LETTER
 
Proteus mirabilis isolate JIE273 was recovered in March 2007 from the urine of an inpatient at Blacktown Hospital, Sydney. In vitro susceptibility tests (Phoenix NMIC/ID-101 panel; BD, Franklin Lakes, NJ) indicated that JIE273 was susceptible to imipenem (MIC, ≤2 µg/ml), cefoxitin (MIC, ≤4 µg/ml), amoxicillin-clavulanate (MIC, ≤4/2 µg/ml), and ticarcillin-clavulanate (MIC, ≤2/2 µg/ml). It had "intermediate" susceptibility to ticarcillin (MIC, 32 µg/ml) but was resistant to ampicillin (MIC, >16 µg/ml), cephalothin (MIC, >16 µg/ml), cefuroxime (MIC, >16 µg/ml), cefotaxime (MIC, >32 µg/ml), ceftriaxone (MIC, >32 µg/ml), ceftazidime (MIC, >16 µg/ml), aztreonam (MIC, >16 µg/ml), trimethoprim-sulfamethoxazole (MIC, >2/38 µg/ml), ciprofloxacin (MIC, >2 µg/ml), levofloxacin (MIC, >4 µg/ml), and nalidixic acid (MIC, >32 µg/ml).

JIE273 was also highly resistant to amikacin, gentamicin, and tobramycin, and this was confirmed by E-test (AB Biodisk, Solna, Sweden) at >256, >1,024, and >256 µg/ml, respectively, suggesting the presence of a 16S rRNA methyltransferase (3). PCR screening of JIE273 for armA (8), rmtA (17), rmtB (19), rmtC (18), and rmtD (5) revealed rmtC only. This gene was originally discovered in P. mirabilis ARS68 in Japan in 2003 (16) and, to our knowledge, has not been reported elsewhere. The patient harboring JIE273 was born in and had recently returned to India but had no history of travel to Japan.

The PCR product obtained with primers ISEcpIR-F (5'-CAATGTGTGAGAAGCAGTCTAAA-3') and rmtC-down (5'-GCGAGGTGTGTTAGAATTTGC-3') contained a gene and flanking sequences identical to those of the original rmtC sequence with GenBank accession no. AB194779 (15). ISEcp1 has been previously shown to promote both the expression and transposition of rmtC (15), and an additional PCR with ISEcp1-5' (6) and RMTC-R rmtC (18) confirmed a complete, uninterrupted copy of ISEcp1 adjacent to rmtC, as in ARS68.

The rmtC gene was transferred from ARS68 to Escherichia coli by electroporation but not conjugation (16). Attempts to transfer rmtC from JIE273 to a rifampin-resistant variant of E. coli DH5{alpha} (DH5{alpha}Rf) by a filter-based (14) or a broth-based (2) conjugation method with selection on amikacin (16 µg/ml) and rifampin (80 µg/ml) were unsuccessful. Repeated attempts to obtain amikacin-resistant (MIC, >16 µg/ml) transformants of E. coli DH5{alpha} by electroporation with DNA prepared from JIE273 by alkaline lysis (13) were also unsuccessful, despite successful transfer of control plasmids.

A "keyhole" effect in a double-disc synergy test (9) with 30-µg cefotaxime, ceftazidime, and aztreonam discs placed 15 mm from a 20/10-µg amoxicillin-clavulanate disc (Bio-Rad, Hercules, CA) suggested an extended-spectrum β-lactamase in JIE273. Known associations between 16S RNA methylases and extended-spectrum β-lactamase genes (3) include blaCTX-M and/or blaSHV with armA or rmtB (19). Neither the blaCTX-M (10), nor the blaSHV (12), nor the blaTEM (1) gene was amplified from JIE273, but a blaVEB (11) amplicon was obtained. A single nucleotide change from blaVEB-4 (GenBank accession no. EF136375) predicts only a conservative substitution (Ile18Val) in the leader peptide. This β-lactamase was designated VEB-6 (http://www.lahey.org/Studies/), and we believe it is the first report of a blaVEB-like gene in Australia.

The general problem of resistance to β-lactams, including carbapenems, is significantly exacerbated by aminoglycoside resistance, since they are often employed together in the treatment of the critically ill. In contrast to patterns observed elsewhere (4), amikacin susceptibility is currently preserved in gentamicin- and tobramycin-resistant isolates with transmissible metalloenzymes in Australia (7). However, the emergence of genes such as rmtC with a broad aminoglycoside resistance spectrum (including amikacin) will limit our future options for dealing with all β-lactamases.


arrow
Nucleotide sequence accession numbers.
 
The nucleotide sequence of the rmtC gene has been submitted to GenBank under accession no. EU144360, and the blaVEB-6 gene has been assigned accession no. EU259884.


arrow
ACKNOWLEDGMENTS
 
Z.Z. is supported by an Endeavor International Postgraduate Research Scholarship from the Australian Government Department of Education, Science and Training and by the Department of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China. S.R.P. is partly supported by a Centre of Clinical Research Excellence grant from the National Health and Medical Research Council of Australia (264625).


arrow
FOOTNOTES
 
{triangledown} Published ahead of print on 19 November 2007. Back


arrow
REFERENCES
 
    1
  1. Caniça, M. M., C. Y. Lu, R. Krishnamoorthy, and G. C. Paul. 1997. Molecular diversity and evolution of blaTEM genes encoding β-lactamases resistant to clavulanic acid in clinical E. coli. J. Mol. Evol. 44:57-65.[CrossRef][Medline]
    2. 2
  2. Coque, T. M., A. Oliver, J. C. Perez-Diaz, F. Baquero, and R. Canton. 2002. Genes encoding TEM-4, SHV-2, and CTX-M-10 extended-spectrum β-lactamases are carried by multiple Klebsiella pneumoniae clones in a single hospital (Madrid, 1989 to 2000). Antimicrob. Agents Chemother. 46:500-510.[Abstract/Free Full Text]
    3. 3
  3. Doi, Y., and Y. Arakawa. 2007. 16S ribosomal RNA methylation: emerging resistance mechanism against aminoglycosides. Clin. Infect. Dis. 45:88-94.[CrossRef][Medline]
    4. 4
  4. Doi, Y., D. de Oliveira Garcia, J. Adams, and D. L. Paterson. 2007. Coproduction of novel 16S rRNA methylase RmtD and metallo-β-lactamase SPM-1 in a panresistant Pseudomonas aeruginosa isolate from Brazil. Antimicrob. Agents Chemother. 51:852-856.[Abstract/Free Full Text]
    5. 5
  5. Doi, Y., A. C. Ghilardi, J. Adams, D. de Oliveira Garcia, and D. L. Paterson. 2007. High prevalence of metallo-β-lactamase and 16S rRNA methylase coproduction among imipenem-resistant Pseudomonas aeruginosa isolates in Brazil. Antimicrob. Agents Chemother. 51:3388-3390.[Abstract/Free Full Text]
    6. 6
  6. Eckert, C., V. Gautier, and G. Arlet. 2006. DNA sequence analysis of the genetic environment of various blaCTX-M genes. J. Antimicrob. Chemother. 57:14-23.[Abstract/Free Full Text]
    7. 7
  7. Espedido, B., J. Iredell, L. Thomas, and A. Zelynski. 2005. Wide dissemination of a carbapenemase plasmid among gram-negative bacteria: implications of the variable phenotype. J. Clin. Microbiol. 43:4918-4919.[Free Full Text]
    8. 8
  8. Galimand, M., P. Courvalin, and T. Lambert. 2003. Plasmid-mediated high-level resistance to aminoglycosides in Enterobacteriaceae due to 16S rRNA methylation. Antimicrob. Agents Chemother. 47:2565-2571.[Abstract/Free Full Text]
    9. 9
  9. Jarlier, V., M. H. Nicolas, G. Fournier, and A. Philippon. 1988. Extended broad-spectrum β-lactamases conferring transferable resistance to newer β-lactam agents in Enterobacteriaceae: hospital prevalence and susceptibility patterns. Rev. Infect. Dis. 10:867-878.[Medline]
    10. 10
  10. Mulvey, M. R., G. Soule, D. Boyd, W. Demczuk, and R. Ahmed. 2003. Characterization of the first extended-spectrum β-lactamase-producing Salmonella isolate identified in Canada. J. Clin. Microbiol. 41:460-462.[Abstract/Free Full Text]
    11. 11
  11. Naas, T., P. Bogaerts, C. Bauraing, Y. Degheldre, Y. Glupczynski, and P. Nordmann. 2006. Emergence of PER and VEB extended-spectrum β-lactamases in Acinetobacter baumannii in Belgium. J. Antimicrob. Chemother. 58:178-182.[Abstract/Free Full Text]
    12. 12
  12. Nüesch-Inderbinen, M. T., H. Hächler, and F. H. Kayser. 1996. Detection of genes coding for extended-spectrum SHV β-lactamases in clinical isolates by a molecular genetic method, and comparison with the E test. Eur. J. Clin. Microbiol. Infect. Dis. 15:398-402.[CrossRef][Medline]
    13. 13
  13. Sambrook, J., and D. W. Russell. 2001. Molecular cloning: a laboratory manual, 3rd ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY.
    14. 14
  14. Valenzuela, J. K., L. Thomas, S. R. Partridge, T. van der Reijden, L. Dijkshoorn, and J. Iredell. 2007. Horizontal gene transfer within a polyclonal outbreak of carbapenem-resistant Acinetobacter baumannii. J. Clin. Microbiol. 45:453-460.[Abstract/Free Full Text]
    15. 15
  15. Wachino, J., K. Yamane, K. Kimura, N. Shibata, S. Suzuki, Y. Ike, and Y. Arakawa. 2006. Mode of transposition and expression of 16S rRNA methyltransferase gene rmtC accompanied by ISEcp1. Antimicrob. Agents Chemother. 50:3212-3215.[Abstract/Free Full Text]
    16. 16
  16. Wachino, J., K. Yamane, K. Shibayama, H. Kurokawa, N. Shibata, S. Suzuki, Y. Doi, K. Kimura, Y. Ike, and Y. Arakawa. 2006. Novel plasmid-mediated 16S rRNA methylase, RmtC, found in a Proteus mirabilis isolate demonstrating extraordinary high-level resistance against various aminoglycosides. Antimicrob. Agents Chemother. 50:178-184.[Abstract/Free Full Text]
    17. 17
  17. Yamane, K., Y. Doi, K. Yokoyama, T. Yagi, H. Kurokawa, N. Shibata, K. Shibayama, H. Kato, and Y. Arakawa. 2004. Genetic environments of the rmtA gene in Pseudomonas aeruginosa clinical isolates. Antimicrob. Agents Chemother. 48:2069-2074.[Abstract/Free Full Text]
    18. 18
  18. Yamane, K., J. Wachino, S. Suzuki, H. Kato, K. Shibayama, K. Kimura, K. Kumiko, I. Satoshi, Y. Ozawa, K. Toshifumi, and Y. Arakawa. 2007. 16S rRNA methylase-producing, gram-negative pathogens, Japan. Emerg. Infect. Dis. 13:642-646.[Medline]
    19. 19
  19. Yan, J. J., J. J. Wu, W. C. Ko, S. H. Tsai, C. L. Chuang, H. M. Wu, Y. J. Lu, and J. D. Li. 2004. Plasmid-mediated 16S rRNA methylases conferring high-level aminoglycoside resistance in Escherichia coli and Klebsiella pneumoniae isolates from two Taiwanese hospitals. J. Antimicrob. Chemother. 54:1007-1012.[Abstract/Free Full Text]
Zhiyong Zong
Sally R. Partridge
Jonathan R. Iredell*
Centre for Infectious Diseases and Microbiology
University of Sydney, Westmead Hospital
Sydney, New South Wales 2145, Australia

* Phone: 61-2-9845-6255, Fax: 61-2-9891-5317, E-mail: jon.iredell{at}swahs.health.nsw.gov.au

Antimicrobial Agents and Chemotherapy, February 2008, p. 794-795, Vol. 52, No. 2
0066-4804/08/$08.00+0     doi:10.1128/AAC.01399-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Folster, J. P., Rickert, R., Barzilay, E. J., Whichard, J. M. (2009). Identification of the Aminoglycoside Resistance Determinants armA and rmtC among Non-Typhi Salmonella Isolates from Humans in the United States. Antimicrob. Agents Chemother. 53: 4563-4564 [Full Text]  
  • Zong, Z., Partridge, S. R., Iredell, J. R. (2009). A blaVEB-1 Variant, blaVEB-6, Associated with Repeated Elements in a Complex Genetic Structure. Antimicrob. Agents Chemother. 53: 1693-1697 [Abstract] [Full Text]  

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Zong, Z.
Right arrow Articles by Iredell, J. R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Zong, Z.
Right arrow Articles by Iredell, J. R.

Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»