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Journal of Clinical Microbiology, November 2000, p. 4000-4005, Vol. 38, No. 11
0095-1137/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Evaluation of an Immunocapture-Agglutination Test (Brucellacapt)
for Serodiagnosis of Human Brucellosis
Antonio
Orduña,1,2,*
Ana
Almaraz,2
Ana
Prado,1
M. Purificación
Gutierrez,1
Agustina
Garcia-Pascual,1
Ana
Dueñas,1
Milagros
Cuervo,1
Ramon
Abad,3
Beatriz
Hernández,1
Belen
Lorenzo,1
Miguel A.
Bratos,1 and
Antonio
Rodriguez
Torres1
Departamento de Microbiología,
Facultad de Medicina,1 Unidad de
Investigación, Hospital Universitario,2
and Laboratorio Regional de Brucelosis, Servicio Territorial de
Salud Pública,3 Valladolid, Spain
Received 11 February 2000/Returned for modification 1 June
2000/Accepted 27 August 2000
 |
ABSTRACT |
We evaluated the validity and the usefulness of a new test for the
diagnosis of human brucellosis based on an immunocapture-agglutination technique. A total of 315 sera from 82 patients with a diagnosis of
brucellosis, 157 sera from patients in whom brucellosis was suspected
but not confirmed, and 412 sera from people living in rural areas with
endemic brucellosis were studied. The seroagglutination test (SAT),
Coombs anti-Brucella test, and Brucellacapt test were evaluated. All
the initial sera from the 82 patients proved to be positive in
Brucellacapt and Coombs tests, while only 75 (91.4%) were positive in
the SAT. If a 
1/160 diagnostic threshold titer was defined for the
Brucellacapt test, Coombs test, and SAT, the sensitivities were 95.1, 91.5, and 65.8%, respectively. Taking the same diagnostic threshold
titer for the 157 sera from the unconfirmed but suspected patients, the
specificities of the Brucellacapt, Coombs, and SAT were 81.5, 96.2, and
100%, respectively; for the 412 control sera, the specificities were
99.0, 99.8, and 100%. The diagnostic efficiency (area below the
receiver operating characteristic curve) of Brucellacapt was 0.987852 (95% confidence interval [CI], 0.95109 to 0.99286), very similar to
the diagnostic efficiency of the Coombs test (0.97611; 95% CI, 0.94781 to 0.99146) and higher than that of SAT (0.91013; 95% CI, 0.86649 to
0.94317). The results of the Brucellacapt test were compared with those
of the Coombs test (correlation coefficient, 0.956; P = 0.000) and SAT (correlation coefficient, 0.866; P = 0.000). The study shows very good correlation between the Brucellacapt
and Coombs tests, with a high concordance between titers obtained in
the two tests. Nevertheless, lower correlation and concordance were
found between the Brucellacapt and Coombs tests when the results for
titers of 1/160 were compared (0.692; P = 0.000). In
acute brucellosis, the Brucellacapt and Coombs tests render positive
titers of 1/160. When the titers are lower, they increase
significantly in the following 30 days, despite the evolution of SAT
titers. In contrast, Brucellacapt and Coombs titers are always high
(1/640) in brucellosis with long evolution, whether SAT titers are
higher or lower than 1/160.
| |
INTRODUCTION |
Brucellosis is a zoonosis caused by
bacteria of the genus Brucella, which affect both humans and
animals such as cattle, sheep, goats, and swine. This disease is
worldwide, with areas of high endemicity such as the Mediterranean,
Middle East, Latin America, and Asia (11, 26). The incidence
in humans ranges widely between different regions, with values of up to
200 cases per 100,000 population.
Human brucellosis has a great variety of clinical manifestations,
making it difficult to diagnose clinically. Therefore, the diagnosis
must be confirmed by isolation of Brucella, mostly from blood culture or by the detection of an immune response to its antigens. The diagnosis of brucellosis based exclusively on
Brucella isolation presents several drawbacks. The slow
growth of Brucella in primocultures may delay diagnosis for
more than 7 days (5, 31, 37). Also, blood culture
sensitivity is often low, ranging from 50 to 90% depending on disease
stage, Brucella species, culture medium, quantity of
circulating bacteria, and the blood culture technique employed
(23, 37). Hence, serological tests play a major role in
cases when the disease cannot be detected by blood culture. However,
the interpretation of these tests is often difficult, particularly in
patients with chronic brucellosis, in reinfections and relapses, and in
areas of endemicity, where a high portion of the population have
antibodies against brucellosis.
Many serological tests have been used for the diagnosis of human
brucellosis. The most commonly used tests are the serum agglutination test (SAT), the Coombs anti-Brucella test, the Rose Bengal
test, and complement fixation. During the last decade, radioimmunoassay (24, 28) and enzyme immunoassay (6, 21, 34) tests
have also been used. These present technical difficulties since they require skilled personnel and high-cost material. Also, interpretation of enzyme immunoassay results is difficult due to the variability of
antigens and technical procedures employed.
Among the techniques used for the diagnosis of human brucellosis, SAT
and the Coombs test are most often used, and their performance in
disease diagnosis and during disease evolution has been studied thoroughly (38). However, their evaluation is sometimes
uncertain, and the interpretation of SAT titers of 
1/160 is
problematic in areas of endemicity, since low SAT titers may be present
in healthy people who previously suffered the disease (6),
in patients during the first stage of the infection (19,
38), and in patients suffering chronic brucellosis or a relapse
(29). Diagnosis of a relapse is particularly difficult and
is most often based on the presence of high titers in the Coombs test
(6, 29). However, this is a long and technically difficult
test, requiring skilled personnel, and so it is not routinely performed in many clinical laboratories.
The convenience of using Brucellacapt, a new serological test for the
diagnosis of human brucellosis based on immunocapture-agglutination of
total anti-Brucella antibodies, is discussed in the present paper.
| |
MATERIALS AND METHODS |
Clinical material.
A total of 884 sera from different groups
of patients were studied. The first 315 sera were from 82 patients with
a diagnosis of brucellosis (78 with acute brucellosis and 4 with
chronic brucellosis). Of the 82 patients, 17 were women (20.7%), with
an average age of 43.0 years, (standard deviation [SD] 20.1; range, 7 to 71 years) and 65 were men (79.2%), with an average age of 33.3 years (SD, 15.1; range, 8 to 64 years). Brucellosis was diagnosed on
the basis of clinical evidence, and the diagnosis was confirmed by isolation of Brucella in blood culture, a SAT titer of
1/160, or a fourfold rise in SAT or Coombs test titers between two
samples collected within 15 to 30 days of each other. At least one
blood culture was carried out for every patient, with positive results in 61 cases. Brucella melitensis biovar 3 was isolated in
all cases. The four patients with chronic brucellosis presented
clinical manifestations for more than 6 months, and in three of them
B. melitensis biovar 3 was isolated. Of the 82 patients, 50 had a clinical and serological follow-up during the first month after diagnosis and every 2 months thereafter for at least 9 months after the
initiation of antibiotic treatment. Six of the patients showed a
relapse or reinfection during the follow-up, evidenced by the
reappearance of symptoms after the end of treatment. In three of the
six, B. melitensis biovar 3 was isolated. Of these six
patients, three experienced the relapse or reinfection 2 months after
the end of treatment and three experienced it between 6 and 12 months
after treatment.
To perform validation studies of serological tests, the first serum
sample obtained from each patient in the course of the current disease
was considered the initial serum sample. Sera obtained during clinical
and serological follow-up were considered evolutive sera.
A further 157 sera from patients in whom brucellosis was suspected but
could not be confirmed were also studied. A positive
Coombs test
(
1/20) and SAT titers of <1/160 were obtained for
84 of these
sera.
A total of 412 sera from people living in rural areas of a region with
endemic brucellosis (Castilla y León, Spain) were
included as
control group. They were randomly selected among people
attending
outpatient clinics. None of the patients was diagnosed
with
brucellosis.
Methods.
SAT, the Coombs anti-Brucella test, and
Brucellacapt were performed for each serum sample. All samples from a
given patient were processed simultaneously. The SAT and Coombs test
were performed in tube by a double-dilution method from an initial 1/20
dilution, using a commercial B. abortus antigen (Linear
Chemicals). SAT reactions were read after a 24-h incubation at 37°C.
The highest serum dilution showing >50% agglutination was considered
the agglutinating titer. The Coombs test was carried out with the SAT
tubes by washing three times with phosphate-buffered saline (pH 7.2) by
centrifugation at 3,000 × g for 20 min. After the last
wash, the bacteria were suspended in 1 ml of phosphate-buffered saline,
and 0.05 ml of previously standardized anti-total human immunoglobulin
(Sanofi Pasteur) was added to each tube. The tube contents was mixed
and incubated at 37°C for 24 h. The results were read as
described above for SAT.
The Brucellacapt test (Vircell SL) was performed as specified by the
manufacturer. Briefly, 0.050-ml samples of serum dilutions
were added
to wells of a U-bottom microtiter plate coated with
anti-total human
immunoglobulin. Then 0.050 ml of an antigen suspension
(colored
B. melitensis bacteria killed by formaldehyde treatment)
was
added to all the wells. The plates were sealed with adhesive
tape and
incubated at 37°C for 24 h in a dark humid chamber. Positive
reactions show agglutination over the bottom of the well. Negative
reactions are indicated by a pellet at the center of the bottom
of the
well.
Statistical analysis.
Data were analyzed with the help of
SPSS 8.0 for Windows and Twobytwo analyzer 1.0 programs. The diagnostic
validity of the Brucellacapt and Coombs tests was evaluated in the 82 initial sera from patients with brucellosis, 157 sera from the
unconfirmed but suspected patients, and 412 from control sera. The
results from Brucellacapt were compared with those from the Coombs test or SAT in all 884 sera studied.
In both studies, sensitivity, specificity, and likelihood ratio for
positive and negative results were calculated. The 95%
confidence
intervals (CI) were calculated for sensitivity and
specificity by the
methods of Fleiss (
17) and Diamond (
13).
The likelihood ratio (LR) for a positive result is given by the ratio
between the probability of a positive result in positives
and negatives
according to the "gold standard." LR values of >10
for positives
are considered conclusive. The LR for a negative
result is given by the
ratio between the probability of a negative
result in positives and
negatives according to the "gold standard."
LR values of <0.1 for
negatives are considered conclusive; values
between 0.1 and 0.2 would
produce moderate changes in the pretest
probability. LR 95% CI were
calculated by the methods of Koopman
(
25), Miettinen and
Nurminen (
27), and Gart and Nam (
20).
Spearman's correlation coefficient was calculated for the correlation
analysis between titers obtained with Brucellacapt and
SAT or the
Coombs
test.
The results of sensitivity and specificity obtained with Brucellacapt,
Coombs test, and SAT titers for different cutoff points
were
graphically represented by a curve of diagnostic efficiency
(receiver
operating characteristic curve or ROC curve). The area
under the curve
was calculated with a corresponding CI. An SPSS
macro developed by
Domènech and Bonillo (
16) was used for this
analysis.
| |
RESULTS |
Usefulness of the Brucellacapt test for the diagnosis of human
brucellosis.
To study the validity of Brucellacapt for the
diagnosis of human brucellosis, initial sera from 82 brucellosis
patients, 157 sera from the unconfirmed but suspected patients, and 412 sera from the control group were included.
All the initial sera from the 82 patients gave titers of
1/20 in the
Brucellacapt and Coombs tests, while only 75 (91.4%)
were positive in
the SAT at the same titer (Table
1). Of 7 SAT-negative
sera, 5 were from patients with acute brucellosis (4 had
positive
blood cultures and 1 seroconverted 15 days later) and 2 were
from
patients with chronic brucellosis (1 with a positive blood
culture).
In the unconfirmed but suspected patients, 86 of the 157 sera
studied (54.8%) gave titers of between 1/20 and 1/640 in the
Brucellacapt
test, 84 (53.5%) were positive in the Coombs test (all
with titers
of <1/320), and 18 (11.4%) were positive in the SAT (all
titers
were <1/80). In the control group, 15 of 412 sera (3.6%) were
Brucellacapt positive (all with titers of
1/1,280) and 5 (1.2%)
were
Coombs positive (all with titers of
1/160). Two sera (0.48%)
from
the control group were SAT positive (both with 1/20 titers).
Based on the results obtained from the 82 initial sera, if a 1/160
diagnostic threshold titer was defined for Brucellacapt,
only 4 initial
sera were negative (95.1% sensitivity) (Tables
1 and
2). These sera had Brucellacapt titers of
1/20 (1 serum
sample) and 1/80 (3 sera). In the Coombs test, 7 initial
sera
showed titers of <1/160 (91.5% sensitivity). All initial sera
with Brucellacapt and Coombs titers of
1/160 were from patients
with
acute brucellosis and evolution periods of less than 30 days.
When
these tests were repeated with sera taken between 15 and
30 days later,
they gave positive results with titers of
1/320
in all cases. If we
take 1/320 as the diagnostic threshold titer,
the Brucellacapt and
Coombs test sensitivity decreased to 91.5
and 82.9%, respectively.
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TABLE 2.
Sensitivity, specificity, and LR, of the SAT, the Coombs
anti-Brucella test, and the Brucellacapt test in the 82 initial sera from brucellosis patients and 157 sera from
unconfirmed suspects
|
|
In the SAT, 28 initial sera had titers of <1/160 (65.8% sensitivity);
23 of them were from acute brucellosis patients, 3 were
from chronic
brucellosis patients, and 2 were from patients experiencing
relapses.
Of these 28 patients, 19 with acute brucellosis and
1 with a relapse
had SAT titers of
1/160 in samples collected
during the following 30 days. Of the 28 SAT-positive patients,
20 (17 with acute brucellosis, 2 with chronic brucellosis, and
1 with a relapse) had positive blood
cultures. Four patients with
acute brucellosis had SAT titers of
1/80
in the initial sera
and the same titer in the follow-up sera, collected
2 months
later.
Using 1/160 as the diagnostic threshold titer, in the group of 157 sera
from unconfirmed but suspected patients, 29 were positive
in the
Brucellacapt (specificity, 81.5%) and 6 were positive in
the Coombs
test (specificity, 96.2%) (Table
2). If 1/320 is taken
as the
positivity threshold, Brucellacapt specificity rose to
97.4% and
Coombs specificity rose to 100%. Using the same diagnostic
threshold
titer (1/160) for the 412 control sera, 4 sera were
Brucellacapt
positive (99.0% specificity) and 1 was Coombs positive
(99.8%
specificity) (data not shown). No control sera had SAT
titers of
1/160.
LR values positive for titers of
1/320 in Brucellacapt were always
above 10 (Table
2). The same was true in the Coombs test
for titers of
1/160. However, for SAT, these positive LR values
were found only for
titers of
1/40. In contrast, negative LR
values were below 0.1 for
titers of
1/320 in Brucellacapt,
1/160
in the Coombs test, and
1/40 in the SAT
test.
The diagnostic efficiency of the Brucellacapt and Coombs tests and SAT
has been studied (Fig.
1). The area below
the ROC curve
for Brucellacapt was 0.987852 (95% CI, 0.95109 to
0.99286), that
for the Coombs test was 0.97611 (95% CI, 0.94781 to
0.99146),
and that for the SAT was 0.91013 (95% CI, 0.86649 to
0.94317).
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|
FIG. 1.
Diagnostic efficiency curves (ROC curves) for the
Brucellacapt test, the Coombs test, and SAT. Area below the ROC curve:
Brucellacapt, 0.97852 (95% CI, 0.95109 to 0.99286); Coombs test,
0.97611 (95% CI, 0.94781 to 0.99146); SAT, 0.91013 (95% CI, 0.86649 to 0.94317).
|
|
The serological behavior of four patients with chronic brucellosis and
six patients who suffered relapse or reinfection was
studied during the
follow-up period. Three of the four patients
with chronic brucellosis
had positive blood cultures (Table
3).
One of these three patients was SAT negative, one had a SAT titer
of
1/40, and one had a SAT titer of 1/160. The Coombs test results
obtained gave titers of 1/640 (two patients) and 1/1,280 (one
patient).
Brucellacapt gave titers of 1/1,280 (one patient) and
1/2,560 (two
patients). The chronic brucellosis patient with a
negative blood
culture was SAT negative and had Coombs and Brucellacapt
titers of
1/5,120 and 1/20,480, respectively (Table
3). Three
of the six patients
with relapse or reinfection during the follow-up
period had positive
blood cultures (Table
4). When their
serological
results before and after the relapse were compared, a rise
in
antibody titers was observed in all cases, although SAT titers
were
never >1/640. Coombs titers were always
1/640 in all the
postrelapse
sera. In these sera, Brucellacapt titers exceeded
Coombs titers in all
cases and were always
1/1,280.
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TABLE 4.
Antibody titer in serum samples taken before and after
relapse or reinfection in the six affected brucellosis patients
|
|
Based on the data obtained from all 884 sera analyzed, the results of
the Brucellacapt test were compared with those of the
Coombs test
(Table
5) and SAT (Table
6). Of 503 negative sera
in the Coombs
test, 29 were Brucellacapt positive (Table
5).
On the other hand, 5 of
the 381 Coombs-positive sera were Brucellacapt
negative (correlation
coefficient, 0.956;
P = 0.000). Of 606 SAT-negative
sera, 127 were Brucellacapt positive (Table
6), and none of the
278 SAT-positive sera was Brucellacapt negative (correlation coefficient,
0.866;
P = 0.000). When only sera with titers of
1/160 in the
Brucellacapt and Coombs tests and SAT were considered,
the correlation
coefficient between the Brucellacapt and Coombs tests
fell to
0.692 (
P = 0.000), while that between the
Brucellacapt test and
SAT fell to 0.448 (
P = 0.000)
(Tables
5 and
6).
| |
DISCUSSION |
The results from the present study show a high sensitivity and
specificity of Brucellacapt for the diagnosis of human brucellosis both
in the first stages of the disease and in cases with long evolution as
well as in relapses and reinfections. All the initial sera from
patients with brucellosis included in the study had Brucellacapt and
Coombs titers of 1/20, while only 91.4% of them were SAT positive.
However, problems in the interpretation arose with the use of a 1/20
diagnostic titer, specially in areas of endemicity, where the
prevalence of anti-Brucella antibodies is high due to
previous episodes of brucellosis or exposure to infected animals in a
high proportion of the population (1, 17, 32). In fact,
positive sera were found in all tests in the control group, which was
made up of individuals from a brucellosis-endemic area. Moreover, low
anti-Brucella titers are found in patients who have been
infected with Yersinia enterocolitica O:9, Pseudomonas maltophilia, and some Salmonella serotypes (7, 12,
15).
The definition of a diagnostic titer, indicative of an active
infection, has not been possible in human brucellosis, even in tests
such as the Coombs test and SAT, which have been in use for a long time
(14). Most authors (8, 10, 31, 36, 38) consider a
SAT titer of 1/160 to be indicative of active brucellosis. However,
active brucellosis cannot be excluded in patients with lower SAT
titers, especially during the first stage of the infection
(6), in chronic brucellosis (4), and in relapses
(29). In the present study, nearly 35% of the initial sera
from infected patients showed SAT titers of <1/160. This implies a
serious limitation for disease diagnosis, especially since prompt
treatment is very important for a good prognosis (33). Our
study shows that titers of 1/320 in Brucellacapt, 1/160 in the
Coombs test, and 1/40 in SAT indicate the existence of brucellosis
with a high degree of probability and titers lower than these allow us
to eliminate the possibility of brucellosis in the majority of cases.
However, when SAT titers are <1/160, particularly in acute
brucellosis, the detection of immunoglobulin M (IgM)-specific
antibodies may be sufficient for the diagnosis of a high proportion of
patients (2, 14, 30). However, IgM antibodies cannot be
detected in some brucellosis patients. According to recent studies by
Smits et al. (35), 11% of patients with brucellosis do not
have detectable levels of specific IgM by immunoblot analysis. Similar
results were found with enzyme immunoassay techniques (3, 4, 6,
34). In these cases, seroconversion accompanied by a significant
rise in antibody titer allows brucellosis to be diagnosed. In this
sense, both IgG and IgM antibodies appear promptly after
Brucella infection (4, 6, 21), and their
concentration rises during the following days (21). Similar
results were found in our study, where low titers in the Brucellacapt
or Coombs test increased during the following 15 or 30 days whether SAT
titers rose or not. In fact, in four patients with acute brucellosis,
neither the initial serum sample nor samples collected during follow-up
showed SAT titers of 1/160, probably due to the early initiation of
therapy. In these cases, the Brucellacapt and Coombs tests gave titers
between two- and fourfold higher than SAT for initial sera and between four- and eightfold higher for sera collected during the follow-up period.
Most studies show that IgM antibodies are not useful for the diagnosis
of chronic brucellosis and relapses (3, 4, 35). In these
cases, SAT titers are often <1/160 (2, 6, 21). However, the
Brucellacapt and Coombs tests behave in a different way from that
described for acute brucellosis. All patients with chronic brucellosis
or relapses had Brucellacapt titers of 1/1,280 and Coombs titers of
1/640. Even in two patients with relapse and two patients with
chronic brucellosis, whose sera had SAT titers of 1/160, the
Coombs and Brucellacapt titers were between 4- and 32-fold higher.
These findings agree with those described by Foz et al. (18)
using the Coombs test to detect chronic brucellosis.
Moreover, Pellicer et al. (29) observed that patients
suffering a relapse had a rise in Coombs titers and specific IgG levels detected by enzyme-linked immunosorbent assay. This increase was also
found in the present study with both the Brucellacapt and Coombs tests
in all cases.
Finally, the study shows very good correlation between the Brucellacapt
and Coombs tests, with a good concordance between titers obtained by
both tests even when only titers higher than 1/160 were compared.
Similar results were found by Gomez et al. (22) with sera
from brucellosis patients or unconfirmed but suspected brucellosis
patients. In fact, our result show that the diagnostic efficiency of
Brucellacapt is equal to that of the Coombs test, as their ROC curves
show. Nevertheless, a lower correlation and concordance were found
between Brucellacapt and SAT.
Briefly, our study shows that the Brucellacapt and Coombs tests have
very similar performances in the diagnosis of human brucellosis. Brucellacapt is more sensitive and usually shows higher titers than the
Coombs test, although its specificity decreases slightly when titers
less than 1/320 are used as the diagnostic threshold. In acute
brucellosis, both tests have positive titers of 1/160. When the
titers are lower, they increase significantly in the following 30 days,
whether or not the SAT titers rise. In contrast, the Brucellacapt and
Coombs titers are always high (1/640) in patients with brucellosis of
long evolution, whether the SAT titers are higher or lower than 1/160.
| |
FOOTNOTES |
*
Corresponding author. Mailing address: Dpto
Microbiología, Facultad de Medicina, Avda Ramon y Cajal s/n,
47005 Valladolid, Spain. Phone: 34 983423063. Fax: 34 983423066. E-mail: orduna{at}med.uva.es.
| |
REFERENCES |
| 1.
|
Araj, G. F., and R. A. Azzam.
1996.
Seroprevalence of Brucella antibodies among persons in high-risk occupations in Lebanon.
Epidemiol. Infect.
117:281-288[Medline].
|
| 2.
|
Araj, G. F., and A. Kaufmann.
1989.
Determination by enzyme-linked immunosorbent assay of immunoglobulin G (IgG), IgM, and IgA to Brucella melitensis major outer membrane proteins and whole-cell heat-killed antigens in sera patients with brucellosis.
J. Clin. Microbiol.
27:1909-1912[Abstract/Free Full Text].
|
| 3.
|
Araj, G. F.,
A. R. Lulu,
M. I. Khateeb,
M. A. Saadah, and R. A. Shakir.
1988.
ELISA versus routine tests in the diagnosis of patients with sistemic and neurobrucellosis.
Acta Pathol. Microbiol. Scand.
96:171-176.
|
| 4.
|
Araj, G. F.,
A. R. Lulu,
M. Y. Mustafa, and M. I. Khateeb.
1986.
Evaluation of ELISA in the diagnosis of acute and chronic brucellosis in human beings.
J. Hyg.
97:457-469.
|
| 5.
|
Ariza, J.
1996.
Brucellosis.
Curr. Opin. Infect. Dis.
9:126-131[CrossRef].
|
| 6.
|
Ariza, J.,
T. Pellicer,
R. Pallarés, and F. Gudiol.
1992.
Specific antibody profile in human brucellosis.
Clin. Infect. Dis.
14:131-140[Medline].
|
| 7.
|
Avhonen, P.,
E. Jansson, and K. Aho.
1969.
Marked cross-agglutination between Brucellae and a subtype of Yersinia enterocolitica.
Acta Pathol. Microbiol. Scand.
75:291-295[Medline].
|
| 8.
|
Buchanan, T. M.,
C. R. Sulzer,
M. K. Frix, and R. A. Feldman.
1974.
Brucellosis in the United States, 1960-1972. An abbattoir-associated disease.
Medicine
53:415-425[CrossRef][Medline].
|
| 9.
|
Castañeda, M. R.
1961.
Laboratory diagnosis of brucellosis in man.
Bull. W. H. O.
24:73-84[Medline].
|
| 10.
|
Colmenero, J. D.,
J. J. Porras,
P. Valdivielso,
E. de Ramón,
M. Cause, and J. Juarez.
1986.
Brucelosis: estudio prospectivo de 100 casos.
Med. Clin.
86:43-48.
|
| 11.
|
Corbel, M. J.
1997.
Brucellosis: an overview.
Emerg. Infect. Dis.
3:213-221[Medline].
|
| 12.
|
Corbel, M. J.,
F. A. Stuart, and R. A. Brewer.
1984.
Observation of serological cross-reactions between smooth Brucella species and organisms of other genera.
Dev. Biol. Stand.
56:341-348[Medline].
|
| 13.
|
Diamond, G. A.
1989.
Limited assurances.
Am. J. Cardiol.
63:99-100[CrossRef][Medline].
|
| 14.
|
Diaz, R.,
I. Moriyón,
C. Gamazo,
B. Alonso-Urmeneta, and M. de la Viuda.
1991.
Laboratory diagnosis of human brucellosis, p. 93-107.
In
M. Plommet (ed.), Prevention and control of brucellosis in the Mediterranean countries. Pudoc Scientific Publishers, Wageningen, The Netherlands.
|
| 15.
|
Diaz, R.,
J. Toyos,
M. D. Salvo,
L. Fernandez-Lago,
B. Alonso,
I. Moriyon, and I. Dorronsoro.
1984.
Studies of the polysaccharide B and native hapten of Brucella and Yersinia enterocolitica serotype 9.
Dev. Biol. Stand.
56:213-220[Medline].
|
| 16.
|
Domènech, J. M., and A. Bonillo.
1998.
Proceso de datos sanitarios con el Sistema SPSS. Documentos del Laboratorio d' estadísitica aplicada i modelització.
Universidad Autónoma de Barcelona, Barcelona, Spain.
|
| 17.
|
Fleiss, J. L.
1981.
Statistical methods for rates and proportions, p. 1-18.
John Wiley & Sons, Inc., New York, N.Y.
|
| 18.
|
Foz, A.,
R. Diaz, and J. Ariza.
1992.
Brucellosis, p. 682-690.
In
J. E. Perea (ed.), Enfermedades infecciosas. Patogénesis y diagnóstico. Salvat, Barcelona, Spain.
|
| 19.
|
Foz, A.,
L. Arcalis,
S. Garriga,
J. Manzanares, and F. Ortiz.
1954.
Valor de algunos métodos de laboratorio en el diagnostico de la brucelosis humana.
Rev. Diagn. Biol.
3:349-383.
|
| 20.
|
Gart, J. J., and J. Nam.
1988.
Approximate interval estimation of the ratio of binomial parameters: a review and corrections for skewness.
Biometrics
44:323-338[CrossRef][Medline].
|
| 21.
|
Gazapo, E.,
J. Gonzalez Lahoz,
J. L. Subiza,
M. Baquero,
J. Gil, and E. de la Concha.
1989.
Changes in IgM and IgG antibody concentrations in brucellosis over time: importance for diagnosis and follow-up.
J. Infect. Dis.
159:219-225[Medline].
|
| 22.
|
Gomez, C.,
C. Rosa,
P. Geijo, and M. A. Escribano.
1999.
Estudio comparativo del test Brucellacapt® con el test de Coombs para Brucella.
Enferm. Infecc. Microbiol. Clin.
17:283-285[Medline].
|
| 23.
|
Gotuzzo, E.,
C. Carrillo,
J. Guerra, and L. Llosa.
1986.
An evaluation of diagnostic methods for brucellosis the value of bone marrow culture.
J. Infect. Dis.
153:122-125[Medline].
|
| 24.
|
Hewitt, W. G., and D. J. Payne.
1984.
Estimation of IgG and IgM Brucella antibodies in infected and non-infected persons by a radioimmune technique.
J. Clin. Pathol.
37:692-696[Abstract/Free Full Text].
|
| 25.
|
Koopman, P. A. R.
1984.
Confidence intervals for the ratio of two binomial proportions.
Biometrics
40:513-517[CrossRef].
|
| 26.
|
López Merino, A.
1989.
Brucellosis in Latin America, p. 151-161.
In
E. J. Young, and M. J. Corbel (ed.), Brucellosis: clinical and laboratory aspects. CRC Press, Inc., Boca Raton, Fla.
|
| 27.
|
Miettinen, O., and M. Nurminen.
1985.
Comparative analysis of two rates.
Stat. Med.
4:213-226[Medline].
|
| 28.
|
Parrat, D.,
K. H. Nielsen, and R. G. White.
1977.
Radioimmunoassay of IgM, IgG and IgA Brucella antibodies.
Lancet
i:1075-1078.
|
| 29.
|
Pellicer, T.,
A. Ariza,
R. Foz,
R. Pallares, and F. Gudiol.
1988.
Specific antibodies during relapse of human brucellosis.
J. Infect. Dis.
157:918-924[Medline].
|
| 30.
|
Reddin, L.,
R. K. Anderson,
R. Jennes, and W. W. Spink.
1965.
Significance of 7s and macroglobulin Brucella agglutinins in human brucellosis.
N. Engl. J. Med.
272:1263-1268.
|
| 31.
|
Rodríguez Torres, A., and J. Fermoso.
1987.
Brucellosis.
Medicine
76:3165-3177. (In Spanish.)
|
| 32.
|
Russel, A. O.,
C. M. Patton, and A. F. Kaufman.
1978.
Evaluation of the card test for diagnosis of human brucellosis.
J. Clin. Microbiol.
7:454-458[Abstract/Free Full Text].
|
| 33.
|
Salata, R. A.
1996.
Brucellosis, p. 1936-1938.
In
J. C. Bennett, and F. Plum (ed.), Cecil textbook of medicine, 20th ed. The W. B. Saunders Co., Philadelphia, Pa.
|
| 34.
|
Saz, J. V.,
M. Beltran,
A. Díaz,
A. Agulla,
F. J. Merino,
P. A. Villasante, and A. C. Velasco.
1987.
Enzyme-linked-immunosorbent assay for diagnosis of brucellosis.
Eur. J. Clin. Microbiol. Infect. Dis.
6:71-74.
|
| 35.
|
Smits, H. L.,
M. A. Basahi,
R. Diaz,
T. Marrodan,
J. T. Douglas,
A. Rocha,
J. Veerman,
M. M. Zheludkov,
O. W. M. Witte,
J. de Jong,
G. C. Gussenhoven,
M. G. A. Goris, and M. A. W. G. van der Hoorn.
1999.
Development and evaluation of rapid dipstick assay for serodiagnosis of acute human brucellosis.
J. Clin. Microbiol.
37:4179-4182[Abstract/Free Full Text].
|
| 36.
|
Spink, W. W.
1956.
The nature of brucellosis, p. 145-190.
University of Minnesota Press, Minneapolis, Minn.
|
| 37.
|
Yagupsky, P.
1999.
Detection of brucellae in blood cultures.
J. Clin. Microbiol.
37:3437-3442[Free Full Text].
|
| 38.
|
Young, E. J.
1991.
Serologic diagnosis of human brucellosis: analysis of 214 cases by agglutination tests and review of the literature.
Rev. Infect. Dis.
13:359-372[Medline].
|
Journal of Clinical Microbiology, November 2000, p. 4000-4005, Vol. 38, No. 11
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Abstract
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