Validation of String Test for Diagnosis of Helicobacter pylori Infections

Abstract

The method of recovering Helicobacter pylori DNA or viable cells absorbed on a string that a person has swallowed and that is retrieved an hour later (string test) should be a useful alternative to traditional analysis of cells or DNA obtained by endoscopy, which is invasive, uncomfortable, relatively costly, and ill-suited for community-based and pediatric studies. Here we assayed the sensitivity and validity of the string test versus conventional endoscopic biopsy for detecting and analyzing H. pylori infection. Forty-four people with gastric complaints were studied using both H. pylori culture and urease gene (ureB) PCR. H. pylori organisms cultured from strings and biopsy specimens from the same patients were fingerprinted by the randomly amplified polymorphic DNA (RAPD) method. Biopsy sections were also hematoxylin and eosin and silver stained for H. pylori detection. H. pylori was cultured from 80% of strings and detected by PCR from 91% of strings from participants whose biopsies had been H. pylori positive by culture, PCR, and/or histology. Strains recovered from strings and biopsy specimens yielded identical or closely related RAPD profiles in each of the 24 cases tested. We conclude that the string test is a useful method for H. pylori recovery and analysis when relatively noninvasive procedures are needed.

Helicobacter pylori Infection in Rural and Urban Dyspeptic Patients from Venezuela

“…This may suggest that difference in socioeconomic conditions, such as lack of appropriate hygiene practices and extremely limited sanitary facilities, associated to life style could play a role. 12,25 Gastric NHPH such as Helicobacter heilmannii and Helicobacter felis have been found in gastric biopsies of symptomatic patients ranging from 0.1% to 0.25% in countries with a high level of socioeconomic development (Italy, Japan, and Germany), whereas a higher prevalence has been found in rural areas or developing countries such as southern China (2%) and Thailand (6.2%). [26][27][28] The gastric NHPH infection has been associated with chronic gastritis in humans and pets (dogs, cats, and pigs).…”

“…E-mail: mocontre@ivic.gob.ve was higher than that thus far reported in other urban localities from Venezuela, which ranged from 49% in Caracas to 76% in Mérida; however, it is in accordance with a report from urban Lima, Peru (91%), shantytown residents. [9][10][11][12] The frequency of genes was 16S rRNA 55.0%, glmM 52.0%, and ureA 54.0% for urban population, while that in the rural group was 95.0%, 72.0%, and 77.0%, respectively ( Table 1). The frequency of appearance of all three genes in string samples taken from Caracas patients was nearly identical, whereas these values were higher for rural patients from Tucupita.…”

“…These studies showed that the string-absorbed gastric juice test is as sensitive as detection in gastroesophageal biopsies taken by endoscopy, allowing an accurate diagnosis of H. pylori infection by a less invasive method, 9-11 as was also validated in Lima, Perú by Velapatiño and others. 12 The presence of cagA (cytotoxin-associated gene A) is considered to be a marker for the virulent H. pylori strains and the cag pathogenicity island (cag-PAI). 2,13 The prevalence of H. pylori infection with strains carrying cagA varies among different populations in Venezuela.…”

Comparación entre las biopsias gástricas sin fijar 24 horas frente a la biopsia convencional para el diagnóstico de Helicobacter pylori en un hospital de referencia de Perú

“…En ese sentido, Velapatiño et al (20) realizaron la validación del entero test para el diagnóstico de la infección por Hp en 44 pacientes peruanos, considerando como prueba patrón la positividad de 35 pacientes (79,5%) medido por biopsia y cultivo de Hp (sumando las positividades parciales), lo que es muy similar a nuestra detección con las BSF (79,2%).…”

Intra-gastric string test: an effective tool for diagnosing tuberculosis in adults unable to produce sputum

“…[12][13][14][15] The string test uses a weighted gelatine capsule containing a coiled absorbent nylon string, with one end of the string protruding from a small hole in the capsule. The trailing part of the string is taped to the patient's cheek and the capsule is swallowed.…”