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Journal of Clinical Microbiology, November 1999, p. 3786-3787, Vol. 37, No. 11
0095-1137/99/$04.00+0
LETTERS TO THE EDITOR
Species versus Biotype Status
 |
LETTER |
I was very disappointed to see that the pointless discussion
regarding the species versus biotype status of Ara
and
Ara+ strains of Burkholderia pseudomallei
continues (3). My laboratory has performed a number of
studies on B. pseudomallei and B. pseudomallei-like strains, and we demonstrated using well-defined
criteria that these should be classified as two separate species
(1). In 1998, the International Journal of
Systematic Bacteriology published a manuscript, based upon
peer-reviewed studies from my laboratory, indicating tht B. pseudomallei-like strains should be awarded separate species
status and that this species should be named Burkholderia
thailandensis (2). The awarding of species status was
based upon significant differences between B. thailandensis and B. pseudomallei, including
distinctive nucleotide sequence differences in 16S rRNA (15 nucleotide dissimilarities), differences in lipopolysaccharide
composition [B. thailandensis synthesizes a repeating
disaccharide having the structure
3)-
-D-glucopyranose-(13)-6-deoxy-
-L-talopyranose-(1; B. pseudomallei strains also produce this repeating
disaccharide as well as a 1,3-linked homopolymer of
2-O-acetylated
6-deoxy--D-manno-heptopyranosyl residues
(4, 5)], differences in colonial morphology on Ashdown's
selective medium (B. thailandensis colonies are smooth and
glossy with a pink pigmentation, while B. pseudomallei colonies are rough and wrinkled with a dark
purple pigmentation [6]), biochemical
differences (B. thailandensis assimilates
L-arabinose, 5-keto-gluconate, and adonitol, and it does
not utilize erythritol and dulcitol as carbon sources; B. pseudomallei does not assimilate L-arabinose,
5-keto-gluconate, and adonitol, and it does utilize erythritol and
dulcitol as carbon sources [6]). B. thailandensis is not associated with human disease, and B. pseudomallei is associated with human disease (6),
B. thailandensis is avirulent for Syrian golden hamsters
(50% lethal dose [LD50] > 105), and
B. pseudomallei is virulent for Syrian golden hamsters (LD50 < 100) (2).
In November 1998, at the International Congress on Melioidosis held in
Bangkok, Thailand, the authors of the article recently published in the
Journal of Clinical Microbiology (3) presented data published in abstract form, showing that distinctive
nucleotide sequence differences in the 16S rRNA gene of
Ara+ and Ara B. pseudomallei could
be detected by a simple PCR system and that these nucleotide
diffferences appeared to be species specific (7).
Additionally, the same group proposed that the species name B. siamensis be given to this new species rather than B. thailandensis, since the former more appropriately describes the geographic location where the organism was first identified. The authors also indicated that Siam is the Thai name for Thailand, and the
taxon siamensis has been used to describe many indigenous species found in Thailand. As the species name B. thailandensis clearly has precedent over B. siamensis, this proposal was not accepted.
When will the madness end?
| |
FOOTNOTES |
*
Phone: (403) 220-2564 Fax:
(403) 283-5241 E-mail: woods{at}acs.ucalgary.ca
| |
REFERENCES |
| 1.
|
Brett, P. J.,
D. DeShazer, and D. E. Woods.
1997.
Characterization of Burkholderia pseudomallei and Burkholderia pseudomallei-like strains.
Epidemiol. Infect.
118:137-148[Medline].
|
| 2.
|
Brett, P. J.,
D. DeShazer, and D. E. Woods.
1998.
Burkholderia thailandensis sp. nov., a Burkholderia pseudomallei-like species.
Int. J. Syst. Bacteriol.
48:317-320[Abstract/Free Full Text].
|
| 3.
|
Dharakul, T.,
B. Tassaneetrithep,
S. Trakulsomboon, and S. Songsivilai.
1999.
Phylogenetic analysis of Ara+ and Ara Burkholderia pseudomallei isolates and development of a multiplex PCR procedure for rapid discrimination between the two biotypes.
J. Clin. Microbiol.
37:1906-1912[Abstract/Free Full Text].
|
| 4.
|
Knirel, Y. A.,
N. A. Paramonov,
A. S. Shaskov,
N. K. Kochetkov,
R. G. Yarullin,
S. M. Farber, and V. I. Efremko.
1992.
Structure of the polysaccharide chains of Pseudomonas pseudomallei lipopolysaccharides.
Carbohydr. Res.
233:185-193[Medline].
|
| 5.
|
Perry, M. B.,
L. L. MacLean,
T. Scholaardt,
L. E. Bryan, and M. Ho.
1995.
Structural characterization of the lipopolysaccharide O antigens of Burkholderia pseudomallei.
Infect. Immun.
63:3348-3352[Abstract].
|
| 6.
|
Suthiekanun, B.,
M. D. Smith,
D. A. B. Dance,
A. L. Walsh,
T. L. Pitt, and N. J. White.
1996.
Biochemical characteristics of clinical and environmental isolates of Burkholderia pseudomallei.
J. Med. Microbiol.
45:408-412[Abstract/Free Full Text].
|
| 7.
|
Tassaneetrithep, B.,
S. Songsivilai,
D. Kanistanon,
S. Trakulsomboon, and T. Dharakul.
1998.
Distinctive nucleotide sequence differences in the 16S rRNA gene of Ara+ and Ara Burkholderia pseudomallei, p. 148.
, abstr. P905. In Program and abstracts of the International Congress on Melioidosis.
|
| | | | |
Donald E. Woods*
Department of
Microbiology and Infectious Diseases
University of Calgary
Health Sciences Centre
3330 Hospital Drive,
NW
Calgary, Alberta T2N 4N1,
Canada
|
| |
AUTHOR'S REPLY |
Our study describes the 16S rRNA gene sequences of
Ara and Ara+ biotypes of B. pseudomallei (2). In fact from a total of 1,488 nucleotides there are 15 nucleotide differences, of which 11 are species or biotype specific (99.26% homology). Our interpretation is
that the degree of differences is smaller than the differences among
species in the genus Burkholderia. The data was discussed among those working in the melioidosis field. Therefore, based on this
evidence we took a conservative approach and used "Ara+
B. pseudomallei" as was commonly used prior to the
proposal of the new species named B. thailandensis in
1998 (1). In our article, however, the published reference
on B. thailandensis has been adequately cited in the
Discussion section (2). There is no reason not to use the
name B. thailandensis if the data being presented support
such a conclusion.
As for the status (species versus biotype) of Ara+
B. pseudomallei, Burkholderia-like
organisms, and B. thailandensis, it is well recognized
by the melioidosis community and me that such organisms differ from the
classical B. pseudomallei in several important aspects, as
described in the Discussion section (2). When such
differences occur, a new species name is proposed (as in this case by
Dr. Woods's group). It should be up to a group's scientific peers to
obtain their own data on the organism, and if it passes the
tests, the issuing of a new species and its name will be generally
accepted. This topic was brought into a discussion at the International
Congress in Melioidosis at the end of 1998 (3). In our
article (2), we presented the result on one aspect of the
topic while acknowledging the differences in several other aspects
reported by others.
The name B. siamensis requires no discussion since it was
not in the article published in 1998 (1) and was not used in our article (2) or elsewhere.
| |
FOOTNOTES |
*
Phone: (662) 4197000
Fax: (662) 418636
E-mail: sissv{at}mahidol.ac.th
| |
REFERENCES |
| 1.
|
Brett, P. J.,
D. DeShazer, and D. E. Woods.
1998.
Burkholderia thailandensis sp. nov., a Burkholderia pseudomallei-like species.
Int. J. Syst. Bacteriol.
48:317-320.
|
| 2.
|
Dharakul, T.,
B. Tassaneetrithep,
S. Trakulsomboon, and S. Songsivilai.
1999.
Phylogenetic analysis of Ara+ and Ara Burkholderia pseudomallei isolates and development of a multiplex PCR procedure for rapid discrimination between the two biotypes.
J. Clin. Microbiol.
37:1906-1912.
|
| 3.
|
Tassaneetrithep, B.,
S. Songsivilai,
D. Kanistanon,
S. Trakulsomboon, and T. Dharakul.
1998.
Distinctive nucleotide sequence differences in the 16S rRNA gene of Ara+ and Ara Burkholderia pseudomallei, p. 148.
, abstr. P905. In Program and abstracts of the International Congress on Melioidosis.
|
| | | | |
Sirirurg Songsivilai*
Department of Immunology
Faculty of Medicine Siriraj Hospital
Mahidol University
2 Prannok Rd.
Bangkok 10700, Thailand
|
Journal of Clinical Microbiology, November 1999, p. 3786-3787, Vol. 37, No. 11
0095-1137/99/$04.00+0
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