RESUMEN
The aim of this study was to develop a non-invasive diagnostic test for the detection of Helicobacter pylori in stool samples from digestive symptomatic patients, using a new protocol of nested-qPCR. A total of 143 patients were invited to participate in the study. A gastric biopsy of each patient was collected for Rapid Urease Testing (RUT) and histology by Giemsa stain. A fecal sample for nested-qPCR analysis was also obtained. DNA was extracted from the fecal samples, and conventional PCR followed by qPCR of the ureC gene of H. pylori was carried out. We evaluated the presence of H. pylori, in 103 females and 40 males, mean (± SD) age of 56.5 ± 14.18. The sensitivity of RUT to detect the infection was 67.0% (95% C.I.: 57.2 - 75.8) and specificity was 92.3% (95% C.I.: 76.5 - 99.1). Histology by Giemsa stain, commonly used as a reference for H. pylori detection, showed a sensitivity of 98.6% (95% C.I.: 92.5 - 100.0) and a specificity of 89.7% (95% C.I.: 72.7 - 97.8). In contrast, detection of H. pylori infection in stools by nested-qPCR showed a sensitivity of 100% (95% C.I.: 94.9 - 100.0) and a specificity of 83.9% (95% C.I.: 66.3 - 94.6). Our test, based in nested-qPCR is a better diagnostic alternative than conventional RUT, and is similar to histology by Giemsa stain in the detection of H. pylori, by which the test could be used for non-invasive diagnosis in clinical practice.
Asunto(s)
Proteínas Bacterianas/genética , Heces/microbiología , Infecciones por Helicobacter/diagnóstico , Helicobacter pylori/aislamiento & purificación , Adulto , Anciano , Femenino , Helicobacter pylori/genética , Humanos , Masculino , Persona de Mediana Edad , Técnicas de Diagnóstico Molecular , Reacción en Cadena en Tiempo Real de la Polimerasa , Sensibilidad y EspecificidadRESUMEN
BACKGROUND: Helicobacter pylori is the most significant pathogen associated with gastric diseases, including gastric cancer. Infected patients with strains that are CagA-positive generally have worse outcomes than those infected with CagA-negative strains. Patients infected with CagA-positive strains have a higher risk for developing gastric cancer. AIM: To determine the prevalence of CagA-positive H. pylori strains in fecal samples of patients from the Coquimbo Region of Chile, using a non-invasive, nested-qPCR method. MATERIAL AND METHODS: We evaluated 160 patients with gastrointestinal symptoms subjected to an upper gastrointestinal endoscopy. DNA was extracted from fecal samples and tested for the presence of H. pylori using nested-qPCR for the ureC gene, and subsequently compared with the results of histology-Giemsa stain from the patients' endoscopic biopsies. When H. pylori was found, the presence of CagA-positive strains was determined via nested-qPCR. RESULTS: The histology-Giemsa stain was positive for H. pylori infection in 123 patients (76.9%), while the analysis of fecal samples detected H. pylori in 129 patients (80.6%). The sensitivity and specificity of nested-qPCR to detect the bacterium was 96.7 and 73.0% respectively. Among patients with the infection, 25% had CagA-positive strains. CONCLUSIONS: In this sample of patients, there is a low prevalence of CagA-positive H. pylori strains.
Asunto(s)
Antígenos Bacterianos/genética , Proteínas Bacterianas/genética , ADN Bacteriano/análisis , Heces/microbiología , Infecciones por Helicobacter/diagnóstico , Helicobacter pylori/genética , Gastropatías/microbiología , Antígenos Bacterianos/aislamiento & purificación , Proteínas Bacterianas/aislamiento & purificación , Endoscopía del Sistema Digestivo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Sensibilidad y Especificidad , Gastropatías/diagnósticoRESUMEN
BACKGROUND: Gastric cancer (GC) ranks as one of the major causes of mortality due to cancer worldwide. In Chile, it is currently the leading cause of cancer death. Identification of novel molecular markers that may help to improve disease diagnosis at early stages is imperative. MATERIALS AND METHODS: Using whole-genome DNA microarrays we determined differential mRNA levels in fresh human GC samples compared to adjacent healthy mucosa from the same patients. Genes significantly overexpressed in GC were validated by RT-PCR in a group of 14 GC cases. RESULTS: The genes CD248, NSD1, RAB17, ABCG8, Ephb1 and P2RY2 were detected as the top overexpressed in GC biopsies. P2RY2, Ephb1 and CD248 showed the best sensitivity for GC detection with values of 92.9%, 85.7% and 64.3% (p<0.05), respectively. Specificity was 85.7%, 71.4% and 71.4% (p<0.05), for each respectively.
Asunto(s)
Antígenos CD/genética , Antígenos de Neoplasias/genética , Regulación Neoplásica de la Expresión Génica/genética , Receptor EphB1/genética , Receptores Purinérgicos P2Y2/genética , Neoplasias Gástricas/genética , Biomarcadores de Tumor , Chile , Humanos , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , ARN Mensajero/genéticaRESUMEN
Background: Helicobacter pylori is the most significant pathogen associated with gastric diseases, including gastric cancer. Infected patients with strains that are CagA-positive generally have worse outcomes than those infected with CagA-negative strains. Patients infected with CagA-positive strains have a higher risk for developing gastric cancer. Aim: To determine the prevalence of CagA-positive H. pylori strains in fecal samples of patients from the Coquimbo Region of Chile, using a non-invasive, nested-qPCR method. Material and Methods: We evaluated 160 patients with gastrointestinal symptoms subjected to an upper gastrointestinal endoscopy. DNA was extracted from fecal samples and tested for the presence of H. pylori using nested-qPCR for the ureC gene, and subsequently compared with the results of histology-Giemsa stain from the patients' endoscopic biopsies. When H. pylori was found, the presence of CagA-positive strains was determined via nested-qPCR. Results: The histology-Giemsa stain was positive for H. pylori infection in 123 patients (76.9%), while the analysis of fecal samples detected H. pylori in 129 patients (80.6%). The sensitivity and specificity of nested-qPCR to detect the bacterium was 96.7 and 73.0% respectively. Among patients with the infection, 25% had CagA-positive strains. Conclusions: In this sample of patients, there is a low prevalence of CagA-positive H. pylori strains.
Asunto(s)
Humanos , Masculino , Femenino , Persona de Mediana Edad , Gastropatías/microbiología , Proteínas Bacterianas/genética , ADN Bacteriano/genética , Helicobacter pylori/genética , Infecciones por Helicobacter/diagnóstico , Heces/microbiología , Antígenos Bacterianos/genética , Gastropatías/diagnóstico , Proteínas Bacterianas/aislamiento & purificación , Reacción en Cadena de la Polimerasa , Endoscopía del Sistema Digestivo , Sensibilidad y Especificidad , Antígenos Bacterianos/aislamiento & purificaciónRESUMEN
Se analizan 6 casos de paragangliomas (5 de cuerpo carotídeo y 1 de la órbita). Se detallan especialmente los aspectos clínicos y de técnica referentes al Paraganglioma orbitario recidivado