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Journal of Clinical Microbiology, November 2000, p. 4303-4303, Vol. 38, No. 11
0095-1137/00/$04.00+0
LETTERS TO THE EDITOR
String Test for Helicobacter pylori
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LETTER |
We were very pleased to read the paper by Samuels et al.
(5) on the usefulness of the gastric string test for culture
of Helicobacter pylori. At last, this nonendoscopic method
for culture of H. pylori is used and recommended to
colleagues in locations other than Europe. Samuels et al. mentioned
that we achieved a 50% culture success rate with the Entero-Test, when
in fact the success rate was 77.8% in the original article and 78.8%
in a letter reply, respectively (2, 3). In the first study
(2), the patients were not selected and had not been
previously defined as H. pylori positive. We evaluated the
endoscopic biopsy culture and the string test culture simultaneously,
using the same culture media. Kopanski et al. (1) also found
that the results of the string test culture were satisfactory in
comparison to those of endoscopic biopsy culture. The sensitivity of
the culture depends on many factors, such as the number and type of
plates used, incubation time, and conditions, etc. If the string is
inoculated in six plates, the sensitivity will obviously be higher than
if it is inoculated in only two plates. Nevertheless, we consider that it is essential to simplify the culture of Helicobacter.
Unfortunately, there are few laboratories that perform antimicrobial
testing of Helicobacter isolates, while others consider it
complex and time-consuming. In a recent paper (4), we stated that we are in favor of introducing routine antimicrobial
susceptibility testing of H. pylori and cited our experience
using the string test, pointing out its convenience and low cost. Up
till now, we have performed antimicrobial susceptibility testing for
over 800 strains of H. pylori obtained with the string test,
with inoculation of only two culture plates for the initial isolation.
Samuels et al. (5) suggested that posttreatment patients
first receive follow-up testing with the urea breath test (UBT) and the
string test be performed only when the UBT is positive. We consider
this approach to be very suitable. However, in recently diagnosed
patients who have not received any prior treatment, the need to perform
the UBT prior to the string test is uncertain.
We also agree with Samuels et al. that the string test is not useful as
a rapid urease test (CLOtest). In our experience, the main problem of
performing the CLOtest using the string is the high number of false
positives due to the presence of contaminant flora in the upper
respiratory tract.
Our first publication aimed to provide information on a nonendoscopic
method for culture of H. pylori. The article by Samuels et
al. will certainly facilitate the increased use of this method. As the
use of the string test becomes more frequent, more suggestions for
improvement, including the most cost-effective type and number of
culture plates, will be made.
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FOOTNOTES |
*
E-mail: labmikro{at}teleline.es
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REFERENCES |
| 1.
|
Kopanski, Z.,
M. Schlegel-Zawadzka,
B. Witkowska,
A. Cienciala, and J. Szczerba.
1996.
Role of the Enterotest in the diagnosis of Helicobacter pylori infections.
Eur. J. Med. Res.
1:520-522[Medline].
|
| 2.
|
Perez-Trallero, E.,
M. Montes,
M. Alcorta,
P. Zubillaga, and E. Tellería.
1995.
Non-endoscopic method to obtain Helicobacter pylori for culture.
Lancet
345:622-623[CrossRef][Medline].
|
| 3.
|
Perez-Trallero, E., and M. Montes.
1995.
String test for Helicobacter pylori.
Lancet
345:1580-1581[CrossRef][Medline].
|
| 4.
|
Pérez-Trallero, E.,
M. Montes,
M. Larrañaga, and J. I. Arenas.
1999.
How long for the routine Helicobacter pylori antimicrobial susceptibility testing? The usefulness of the string test to obtain Helicobacter for culture.
Am. J. Gastroenterol.
94:3075-3076[Medline].
|
| 5.
|
Samuels, A. L.,
H. M. Windsor,
G. Y. Ho,
L. D. Goodwin, and B. J. Marshall.
2000.
Culture of Helicobacter pylori from a gastric string may be an alternative to endoscopic biopsy.
J. Clin. Microbiol.
38:2438-2439[Abstract/Free Full Text].
|
| | | | |
Emilio Pérez-Trallero*
Milagrosa Montes
Microbiology Department
Complejo Hospitalario Donostia
P° Dr. Beguiristain s/n
20014 San Sebastián, Spain
|
| |
AUTHORS' REPLY |
We note the important comments of Perez-Trallero and Montes above
regarding the usefulness of the string test for noninvasive recovery of
H. pylori. Our work (2) was based on their
previous results, although, with more intensive laboratory methods, we were able to achieve a very high sensitivity (97%). Thus, the string
test could be used as the main test for H. pylori, either for initial diagnosis or for follow-up posttreatment. However, we do
not believe that culture and sensitivity are essential for initial
diagnosis since current therapies give cure rates of greater than 80%
(3). Therefore, initial diagnosis with serology or a simple
UBT (1) is adequate for most patients. On the other hand,
the string test can play an important role in patients who fail
antibiotic therapy, in which case sensitivity testing is worthwhile.
Even in follow-up, however, we believe that patients prefer the 10-min
UBT, after which only the 20% of patients who are still H. pylori positive need undergo the string test. We reiterate the
findings in our study that patients preferred the string test over endoscopy.
We do agree that there is room for improvement in the string test
methodology, which is still rather labor-intensive, requiring so many
culture plates.
| |
FOOTNOTES |
| |
REFERENCES |
| 1.
|
Peura, D. A.,
D. J. Pambianco,
K. R. Dye,
C. Lind,
H. F. Frierson,
S. R. Hoffman,
M. J. Combs,
E. Guilfoyle, and B. J. Marshall.
1996.
Microdose 14C-urea breath test offers diagnosis of Helicobacter pylori in 10 minutes.
Am. J. Gastroenterol.
91:233-238[Medline].
|
| 2.
|
Samuels, A. L.,
H. M. Windsor,
G. Y. Ho,
L. D. Goodwin, and B. J. Marshall.
2000.
Culture of Helicobacter pylori from a gastric string may be an alternative to endoscopic biopsy.
J. Clin. Microbiol.
38:2438-2439.
|
| 3.
|
Van Oijen, A. H. A. M.,
A. L. Verbeek,
J. B. M. J. Jansen, and W. A. De Boer.
2000.
Treatment of Helicobacter pylori infection with ranitidine bismuth citrate- or proton pump inhibitor-based triple therapies.
Aliment. Pharmacol. Ther.
14:991-999[Medline].
|
| | | | |
Barry J. Marshall
Helen M. Windsor
Department of Microbiology
University of Western Australia
QEII Medical Centre
Hospital Ave.
Nedlands, Perth 6907
Australia
|
Journal of Clinical Microbiology, November 2000, p. 4303-4303, Vol. 38, No. 11
0095-1137/00/$04.00+0
This article has been cited by other articles:
-
Megraud, F., Lehours, P.
(2007). Helicobacter pylori Detection and Antimicrobial Susceptibility Testing. Clin. Microbiol. Rev.
20: 280-322
[Abstract]
[Full Text]
