Previous Article | Next Article 
Antimicrobial Agents and Chemotherapy, April 1999, p. 995-996, Vol. 43, No. 4
0066-4804/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
LETTERS TO THE EDITOR
Disruption of vanS by IS1216V in a
Clinical Isolate of Enterococcus faecium with
VanA Glycopeptide Resistance
 |
LETTER |
The elements that mediate VanA glycopeptide resistance in
enterococci are heterogeneous. Twenty-four distinct VanA elements were
identified among a collection of enterococci isolated from hospital
patients and nonhuman sources in the United Kingdom (9). Despite their diversity, all these elements showed extensive homology with the prototype VanA transposon, Tn1546, from
Enterococcus faecium BM4147 (2); specifically,
the vanRSHAX genes, which are critical for the expression of
glycopeptide resistance, were conserved in all 24 elements
(8).
We recently identified a blood culture isolate of E. faecium
(designated ARMRL 26) in which the vanRSHAX gene cluster was distinct from that observed in all the other United Kingdom strains examined. The strain yielded a long PCR (L-PCR) amplicon larger than
the expected size of 4.4 kb (8), and digestion of this amplicon with DdeI indicated loss of the 418-bp fragment
present in Tn1546 digests and the appearance of a new
fragment of ca. 1 kb (Fig. 1). As the
418-bp fragment results from digestion of Tn1546 at
nucleotide positions 5382 and 5800, the loss of this fragment suggested
an intragenic insertion located towards the 3' end of vanS.
Sequencing detected a copy of the insertion sequence IS1216V
(1) flanked by 8-bp direct repeats of GCTTCCAG
(corresponding to Tn1546 nucleotides 5761 to 5768) and
consistent with target site duplication following a transposition
event. Insertion at this position would be predicted to cause the loss
of 11 amino acids (AMPDLVDKRRS) from the C terminus of the VanS peptide
and their possible replacement by 10 amino acids
(GFCCKVLBKE) resulting from read-through of the
inserted IS1216V sequence. It is unlikely that this change
would affect the function of the VanS sensor peptide, because the
critical residues remain intact (7). Even if the insertion
did cause a functional change, VanS is not essential for expression of
glycopeptide resistance (3). Strain ARMRL 26 had a normal
VanA phenotype (vancomycin and teicoplanin MICs of >32 µg/ml).
View larger version (40K):
[in this window]
[in a new window]
|
FIG. 1.
Digestion with DdeI of vanRSHAX
L-PCR amplicons derived from E. faecium BM4147 containing
Tn1546 (lane a) or E. faecium ARMRL 26 (lane b).
Sizes are shown in base pairs.
|
|
To our knowledge, E. faecium ARMRL 26 is only the second
glycopeptide-resistant enterococcus in which an insertion has been identified within a van gene; disruption of vanY
by IS1476 has been reported previously (6). L-PCR
has been stated previously to be a useful method for fingerprinting and
comparing glycopeptide resistance elements for epidemiological and
evolutionary purposes (4, 8). This report further emphasizes
the ability of L-PCR to identify rapidly enterococci that have
insertions within the vanRSHAX gene cluster. It would
therefore detect readily strains that carry copies of IS1251
in the vanS-vanH intergenic region which have been
documented in the United States (5). Furthermore, restriction fragment length polymorphism analysis of the resulting amplicons can be used to pinpoint the likely position of the insertion and so permit relevant sequencing, allowing cost-effective analysis of
VanA elements to be undertaken.
| |
ACKNOWLEDGMENTS |
A. Darini was funded by a grant from the Fundacao de Amparo a
Pesquisa do Estado de Sao Paulo, Brazil.
| |
FOOTNOTES |
*
Phone: 44-181-200-4400
Fax: 44-181-200-7449
E-mail: nwoodford{at}phls.nhs.uk
| |
REFERENCES |
| 1.
|
Arthur, M.,
F. Depardieu,
G. Gerbaud,
M. Galimand,
R. Leclercq, and P. Courvalin.
1997.
The VanS sensor negatively controls VanR-mediated transcriptional activation of glycopeptide resistance genes in Tn1546 and related elements in the absence of induction.
J. Bacteriol.
179:97-106[Abstract/Free Full Text].
|
| 2.
|
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].
|
| 3.
|
Arthur, M.,
C. Molinas, and P. Courvalin.
1992.
The VanS-VanR two-component regulatory system controls synthesis of depsipeptide peptidoglycan precursors in Enterococcus faecium BM4147.
J. Bacteriol.
174:2582-2591[Abstract/Free Full Text].
|
| 4.
|
Haaheim, H.,
K. H. Dahl,
G. S. Simonsen,
O. Olsvik, and A. Sundsfjord.
1998.
Long PCRs of transposons in the structural analysis of genes encoding acquired glycopeptide resistance in enterococci.
BioTechniques
24:432-437[Medline].
|
| 5.
|
Handwerger, S.,
J. Skoble,
L. F. Discotto, and M. J. Pucci.
1995.
Heterogeneity of the vanA gene cluster in clinical isolates of enterococci from the northeastern United States.
Antimicrob. Agents Chemother.
39:362-368[Abstract/Free Full Text].
|
| 6.
|
MacKinnon, M. G.,
M. A. Drebot, and G. J. Tyrell.
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].
|
| 7.
|
Morel-Deville, F.,
F. Fauvel, and P. More.
1998.
Two-component signal-transducing systems involved in stress responses and vancomycin susceptibility in Lactobacillus sakei.
Microbiology
144:2873-2883[Abstract/Free Full Text].
|
| 8.
|
Palepou, M.-F. I.,
A.-M. A. Adebiyi,
C. H. Tremlett,
L. B. Jensen, and N. Woodford.
1998.
Molecular analysis of diverse elements mediating VanA glycopeptide resistance in enterococci.
J. Antimicrob. Chemother.
42:605-612[Abstract/Free Full Text].
|
| 9.
|
Woodford, N.,
A.-M. A. Adebiyi,
M.-F. I. Palepou, and B. D. Cookson.
1998.
Diversity of VanA glycopeptide resistance elements in enterococci from humans and nonhuman sources.
Antimicrob. Agents Chemother.
42:502-508[Abstract/Free Full Text].
|
| | | | |
Ana Lucia da Costa Darini
Marie-France I. Palepou
Dorothy James
Neil Woodford*
Antibiotic Resistance Monitoring
and Reference Laboratory
Central Public Health Laboratory
London NW9 5HT
United Kingdom
|
Antimicrobial Agents and Chemotherapy, April 1999, p. 995-996, Vol. 43, No. 4
0066-4804/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
-
Park, I. J., Lee, W. G., Shin, J. H., Lee, K. W., Woo, G. J.
(2008). VanB Phenotype-vanA Genotype Enterococcus faecium with Heterogeneous Expression of Teicoplanin Resistance. J. Clin. Microbiol.
46: 3091-3093
[Abstract]
[Full Text]
-
Novais, C., Freitas, A. R., Sousa, J. C., Baquero, F., Coque, T. M., Peixe, L. V.
(2008). Diversity of Tn1546 and Its Role in the Dissemination of Vancomycin-Resistant Enterococci in Portugal. Antimicrob. Agents Chemother.
52: 1001-1008
[Abstract]
[Full Text]
-
Robredo, B., Torres, C., Singh, K. V., Murray, B. E.
(2000). Molecular Analysis of Tn1546 in vanA-Containing Enterococcus spp. Isolated from Humans and Poultry. Antimicrob. Agents Chemother.
44: 2588-2589
[Full Text]
-
Donabedian, S., Hershberger, E., Thal, L. A., Chow, J. W., Clewell, D. B., Robinson-Dunn, B., Zervos, M. J.
(2000). PCR Fragment Length Polymorphism Analysis of Vancomycin-Resistant Enterococcus faecium. J. Clin. Microbiol.
38: 2885-2888
[Abstract]
[Full Text]
Top
Letter
References
