Diagnosis of Helicobacter pylori: comparison of an urease test, histological visualization of curved bacteria and culture

Diagnóstico del Helicobacter pylori: comparación entre la prueba de urease, examen histológico de bacterias curvas y el cultivo

BRIEF COMMUNICATION

Diagnosis of Helicobacter pylori: comparison of an urease test, histological visualization of curved bacteria and culture

Diagnóstico del Helicobacter pylori: comparación entre la prueba de urease, examen histológico de bacterias curvas y el cultivo

Francisco Hernández^I; Patrícia Rivera^II; Manuel Sigarán^III; Jorge Miranda^IV

^ICentro de Investigación y Diagnóstico en Parasitología y Departamento de Microbiología, Facultad de Microbiología Universidad de Costa Rica, San José, Costa Rica

^IIServicio de Anatomía Patológica, Hospital Nacional de Niños. San José, Costa Rica

^IIIEscuela de Medicina, Universidad de Costa Rica. San José, Costa Rica

^IVServicio de Gastroscopía, Hospital México, San José. Costa Rica

SUMMARY

Helicobacter pylori was investigated in 189 patients for culture, microscopic visualization of campylobacter-like organisms (CLO) and a ten minute urease test. In 136 (72%) the bacteria was isolated, and in 98 of them CLO were histologically detected. Specificity, sensitivity, positive and negative predictive values of microscopic visualization of CLO were: 0.77, 0.73, 0.97 and 0.51, respectively; 98 culture-positive patients were urease test positive. Specificity, sensitivity, positive and negative predictive values of the urease test were: 0.83, 0.72, 0.92 and 0.54, respectively. Comparing the urease test with culture of H. pylori combined with microscopic visualization of CLO, its specificity, sensitivity, positive and negative predictive values were: 0.95, 0.71, 0.98 and 0.48, respectively. Probably, these values are not real, since bacteria different from H. pylori could be misclassified as CLO.

Key words: Campylobacter pylori; Helicobacter pylori; Diagnostic; Technical assay; Campylobacter-like organisms; Urease test.

RESUMEN

Se investigo la presencia de Helicobacter pylori en 189 pacientes, mediante cultivo, visualización microscópica de organismos parecidos a Campylobacter (OPC) y una prueba rápida de ureasa. La bacteria se aisló de 136 (72%) casos y en 98 de ellos se observaron OPC. La especificidad, sensibilidad y los valores pedictivos positivo y negativo para la visualización microscópica de OPC fueron: 0.77,0.73,0.97 y 0.51 respectivamente. La prueba de ureasa fue positiva en 98 de los pacientes positivos por cultivo. La especificidad, sensibilidad y los valores predictivos positivo y negativo para la prueba de ureasa fueron: 0.83,0.72,0.92 y 0.54 respectivamente. Cuando se comparó la prueba de urease con el diagnóstico de H. pylori realizado combinando el cultivo con la visualización microscópica de OPC, su especificidad, sensibilidad y los valores predictivos positivo y negativo fueron: 0.95,0.71, 0.98 y 0.48 respectivamente. Esta última condición no es real por cuanto microscópicamente otras bacterias diferentes de H. pylori podrían ser erróneamente clasificadas como OPC.

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ACKNOWLEDGEMENTS

We thanks Dr. Bernal Fernández, MSc Julian Monge-Nágera and Dr. Fernando Brenes for their suggestions on the manuscript, and the staff of the Endoscopio Service of the Hospital México, San José, Costa Rica, for their help in this study. This work was supported by the Vice-president of Research from the University of Costa Rica.

Recebido para publicação em 16/3/1990.

Aceito para publicação em 08/11/1990.

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Publication Dates

• Publication in this collection
  12 Sept 2006
• Date of issue
  Feb 1991

History

• Accepted
  08 Nov 1990
• Received
  16 Mar 1990