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Antimicrobial Agents and Chemotherapy, April 2005, p. 1666-1667, Vol. 49, No. 4
0066-4804/05/$08.00+0 doi:10.1128/AAC.49.4.1666-1667.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
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Nucleotide Sequence of IS1678, an Insertion Sequence in the vanA Cluster of Enterococci
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Resistance to glycopeptide antibiotics in enterococci is mediated most frequently by the vanA gene cluster, which is found in both humans and animals (1, 8). This vanA gene cluster is carried on transposon Tn1546 or by closely related elements that contain vanR, vanS, vanH, vanA, vanX, and vanZ (1). Detailed molecular analyses of Tn1546-like elements in enterococcal isolates have revealed the presence of variations. These variations include the integration of insertion sequences (ISs) with or without a deletion around the insertion site, point mutations, and deletions (2, 6). Until now, six kinds of IS elements had been found in Tn1546-like elements: IS1542, IS19, IS1216V, IS1251, IS1216V-IS3-like, and IS1476 (3, 5, 9). For the first time, we report here an IS element located in Tn1546-like elements. This IS element has been detected in the vanX-vanY intergenic region of a poultry isolate of Enterococcus faecium, which is resistant to vancomycin.
Six vanA enterococci, which were isolated from poultry feces between 1998 and 1999 in Korea, were investigated by PCR with primers specific for regions flanking the vanX-vanY region (7). E. faecium BM4147 with a prototype of Tn1546 was used as a control. Three isolates (SN119-1, SN128-1, and SN154-1) produced PCR amplicons larger than that produced by E. faecium BM4147, and the PCR amplicons from the three isolates were purified and sequenced. Two isolates, SN119-1 and SN128-1, had integration of IS1216V in the vanX-vanY intergenic region, while one isolate, SN154-1, had an unknown sequence in the vanX-vanY intergenic region which has the characteristics of an IS element. This previously unknown IS element has been now designated IS1678.
IS1678 is characterized by (i) its size of 1,678 bp, which is larger than that of the other ISs found in the Tn1546-like element; (ii) its 1,320-bp open reading frame (ORF) for encoding a putative 440-amino-acid protein; (iii) its 24-bp terminal imperfect inverted repeating sequences; (iv) its 5-bp duplication of target DNA; and (v) its ORF showing high homology at amino acid levels with transposases of other IS elements in gram-positive bacteria, as reported in the GenBank database (Fig. 1). A BLAST search yielded the highest scores of identity with the transposase in Bacillus halodurans (52%) (GenBank accession no. NP_244854) and with the IS1380-SpnI transposase in Streptococcus pneunoniae (41%) (4). There were no similar IS elements at the DNA sequence level.
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FIG. 1. Schematic representation of the IS1678 located in the vanX-vanY intergenic region of E. faecium SN154-1. IS1678 is boxed. Imperfect inverted repeats, 24 bp each, are underlined. Repeated nucleotides are indicated in boldface. The 5-bp direct repeats generated by target duplication are double underlined. The positions of the first nucleotide upstream and the first nucleotide downstream from the IS insertion sites, which are based on the sequence of Tn1546, are depicted.
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1,024) and teicoplanin (MIC = 128). In summary, we have found a new IS-like element, IS1678, in the vanX-vanY intergenic region of E. faecium that was isolated from poultry and that shows vancomycin resistance. Fifty-two vanA enterococci that were isolated from poultry meat and feces in 2003 were also investigated, but all enterococci had the same amplicons the same size as those in E. faecium BM4147, except one isolate, M44, which had no amplicons (W. K. Jung, J. Y. Lim, N. H. Kwon, J. M. Kim, S. K. Hong, H. C. Koo, S. H. Kim, Y. Ike, K. Tanimoto, and Y. K. Park, unpublished data).
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TopLetterNucleotide sequence accession...References |
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The complete nucleotide sequence of IS1678 can be found in GenBank under accession no. AY859490.
This study was supported by the Technology Development Program for Agriculture and Forestry, Ministry of Agriculture and Forestry, Republic of Korea (grant No. 201102032SB010), and in part by the Brain Korea 21 project in Agricultural Biotechnology.
We thank K. Tanimoto, Laboratory of Bacterial Drug Resistance, Gunma University School of Medicine, Japan, for helpful discussions.
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TopLetterNucleotide sequence accession...References |
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- Arthur, M., C. Molinas, F. Depardieu, and P. Courvalin. 1993. Characterization of Tn1546, a Tn3-related transposon conferring glycopeptide resistance by synthesis of depsipeptide peptidoglycan precursors in Enterococcus faecium BM4147. J. Bacteriol. 175:117-127.
[Abstract/Free Full Text] - Brown, A. R., A. C. Townsley, and S. G. Amyes. 2001. Diversity of Tn1546 elements in clinical isolates of glycopeptide-resistant enterococci from Scottish hospitals. Antimicrob. Agents Chemother. 45:1309-1311.
[Abstract/Free Full Text] - Huh, J. Y., W. G. Lee, K. Lee, W. S. Shin, and J. H. Yoo. 2004. Distribution of insertion sequences associated with Tn1546-like elements among Enterococcus faecium isolates from patients in Korea. J. Clin. Microbiol. 42:1897-1902.
[Abstract/Free Full Text] - Iannelli, F., M. R. Oggioni, and G. Pozzi. 2002. Allelic variation in the highly polymorphic locus pspC of Streptococcus pneumoniae. Gene 284:63-71.[CrossRef][Medline]
- MacKinnon, M. G., M. A. Drebot, and G. J. Tyrrell. 1997. Identification and characterization of IS1476, an insertion sequence-like element that disrupts VanY function in a vancomycin-resistant Enterococcus faecium strain. Antimicrob. Agents Chemother. 41:1805-1807.[Abstract]
- Schouten, M. A., R. J. Willems, W. A. Kraak, J. Top, J. A. Hoogkamp-Korstanje, and A. Voss. 2001. Molecular analysis of Tn1546-like elements in vancomycin-resistant enterococci isolated from patients in Europe shows geographic transposon type clustering. Antimicrob. Agents Chemother. 45:986-989.
[Abstract/Free Full Text] - Seo, K. S., J. Y. Lim, H. S. Yoo, W. K. Bae, and Y. H. Park. Comparison of vancomycin-resistant enterococci isolates from human, poultry and pigs in Korea. Vet. Microbiol., in press.
- van den Braak, N., A. van Belkum, M. van Keulen, J. Vliegenthart, H. A. Verbrug, and H. P. Endtz. 1998. Molecular characterization of vancomycin-resistant enterococci from hospitalized patients and poultry products in The Netherlands. J. Clin. Microbiol. 36:1927-1932.
[Abstract/Free Full Text] - Willems, R. J., J. Top, N. van den Braak, A. van Belkum, D. J. Mevius, G. Hendriks, M. van Santen-Verheuvel, and J. D. A. van Embden. 1999. Molecular diversity and evolutionary relationships of Tn1546-like elements in enterococci from humans and animals. Antimicrob. Agents Chemother. 43:483-491.
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Woo Kyung Jung Soon Keun Hong Hye Cheong Koo Nam Hoon Kwon Yong Ho Park* Department of Microbiology, College of Veterinary Medicine, and School of Agricultural Biotechnology Seoul National University Sillim-dong, Gwanak-gu Seoul 151-742, Korea
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| * Phone: 82-2-880-1257,Fax: 82-2-871-7524,E-mail: yhp{at}snu.ac.kr |
Antimicrobial Agents and Chemotherapy, April 2005, p. 1666-1667, Vol. 49, No. 4
0066-4804/05/$08.00+0 doi:10.1128/AAC.49.4.1666-1667.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
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