<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0034-7744</journal-id>
<journal-title><![CDATA[Revista de Biología Tropical]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. biol. trop]]></abbrev-journal-title>
<issn>0034-7744</issn>
<publisher>
<publisher-name><![CDATA[Universidad de Costa Rica]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0034-77442020000200551</article-id>
<article-id pub-id-type="doi">10.15517/rbt.v68i2.39349</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Validación de una prueba serológica para detectar la infección por Helicobacter pylori en Costa Rica]]></article-title>
<article-title xml:lang="en"><![CDATA[Validation of a serological test for Helicobacter pylori infection in Costa Rica]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Méndez-Chacón]]></surname>
<given-names><![CDATA[Ericka]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
<xref ref-type="aff" rid="Aaf"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Ramírez]]></surname>
<given-names><![CDATA[Vanessa]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Malespín-Bendaña]]></surname>
<given-names><![CDATA[Wendy]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Pérez-Pérez]]></surname>
<given-names><![CDATA[Guillermo]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Une]]></surname>
<given-names><![CDATA[Clas]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad de Costa Rica  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad de Costa Rica  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Universidad de Nueva York  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>USA</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>06</month>
<year>2020</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>06</month>
<year>2020</year>
</pub-date>
<volume>68</volume>
<numero>2</numero>
<fpage>551</fpage>
<lpage>562</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_arttext&amp;pid=S0034-77442020000200551&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_abstract&amp;pid=S0034-77442020000200551&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_pdf&amp;pid=S0034-77442020000200551&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract  Introduction: Helicobacter pylori is a Gram-negative bacterium capable to survive and multiply in the gastric mucosa. It is the most prominent factor in the development of chronic atrophic gastritis, peptic ulcer, adenocarcinoma and MALT lymphoma. It is estimated that half the world population is infected. The economic cost and impact on the quality of life caused by H. pylori are important. There are several methods to detect the bacteria, but some are invasive, expensive, or both.  Objective:  We compare an inexpensive serological test based on ELISA for the detection of IgG, using the urea breath test (PYtest) as the reference method.  Methods: The area under the ROC curve, sensitivity, specificity and predictive values were calculated. A subset of 45 samples was used for validation of the ELISA test, while the assay was evaluated with 185 additional samples.  Results:  The cut-off point to discriminate between positive and negative infection status by H. pylori was 0.75, using the optical density ratio of each serum and a positive control. With a higher value of the ratio, the probability of being infected increased. Using this criterion, the test showed a sensitivity of 91.4 % and specificity of 93.7 %. All diagnostic values improved when a gray zone was considered.  Conclusion:  The serological test developed here is equivalent to the urea breath test. However, the serological test is more accessible to the general population because of its lower cost. This serological test could be used in large-scale clinical research.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Resumen  Introducción: Helicobacter pylori es una bacteria Gram negativa capaz de sobrevivir y multiplicarse en la mucosa gástrica humana. Es el factor más importante en el desarrollo de gastritis atrófica crónica, úlcera péptica, linfoma MALT y adenocarcinoma. Se estima que la mitad de la población mundial está infectada con esta bacteria. La baja en calidad de vida y el costo económico causados por la infección por H. pylori son importantes. Existen varios métodos para su diagnóstico, pero algunos son invasivos, de alto costo o ambos.  Objetivo:  Comparar una prueba serológica de bajo costo basada en la técnica de ELISA para detección de IgG, usando la prueba de urea en aliento (PYtest) como método de referencia.  Métodos:  Se calculó el área bajo la curva ROC, sensibilidad, especificidad y valores predictivos. Se utilizaron 45 muestras de suero para validar la prueba de ELISA, mientras que para su evaluación se usaron otras 185 muestras de suero.  Resultados:  El punto de corte para discriminar entre positivos y negativos para la infección por H. pylori fue de 0.75 en la razón de densidad óptica entre los sueros de las muestras y el control positivo. A mayor valor de la razón, más probabilidad de ser positivo para la infección. Usando este criterio, la prueba tuvo una sensibilidad del 91.4 % y una especificidad del 93.7 %. Todos los valores diagnósticos mejoran al considerar una zona gris.  Conclusiones:  En la población estudiada, la prueba serológica se comporta de forma equivalente a la prueba de urea en aliento. Tiene la ventaja de que es más asequible a la población general por su bajo costo. La prueba podría ser usada en investigación clínica a gran escala.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Helicobacter pylori]]></kwd>
<kwd lng="en"><![CDATA[gastritis]]></kwd>
<kwd lng="en"><![CDATA[gastric cancer]]></kwd>
<kwd lng="en"><![CDATA[ELISA]]></kwd>
<kwd lng="en"><![CDATA[IgG]]></kwd>
<kwd lng="en"><![CDATA[serology]]></kwd>
<kwd lng="en"><![CDATA[sensitivity]]></kwd>
<kwd lng="en"><![CDATA[specificity.]]></kwd>
<kwd lng="es"><![CDATA[Helicobacter pylori]]></kwd>
<kwd lng="es"><![CDATA[gastritis]]></kwd>
<kwd lng="es"><![CDATA[cáncer gástrico]]></kwd>
<kwd lng="es"><![CDATA[ELISA]]></kwd>
<kwd lng="es"><![CDATA[IgG]]></kwd>
<kwd lng="es"><![CDATA[serología]]></kwd>
<kwd lng="es"><![CDATA[sensibilidad]]></kwd>
<kwd lng="es"><![CDATA[especificidad.]]></kwd>
</kwd-group>
</article-meta>
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