Alimentary Tract
Dual-priming oligonucleotide-based multiplex PCR using tissue samples from the rapid urease test kit for the detection of Helicobacter pylori in bleeding peptic ulcers

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Abstract

Background

In patients with peptic ulcer bleeding (PUB), diagnostic tests for Helicobacter pylori (H. pylori) infection have low sensitivity. The aim of our study was to investigate the diagnostic yield of dual-priming oligonucleotide-based multiplex (DPO)-PCR using tissue samples from the rapid urease test (RUT, CLO®test) kit in patients with PUB.

Methods

We prospectively enrolled patients with PUB. During second-look endoscopy, gastric biopsy specimens for histology and RUT were obtained from a total of 170 patients. DPO-PCR tests were performed on tissue samples obtained from the CLO®test kit. If testing for H. pylori was negative, endoscopy with re-biopsy was performed 8 weeks after the bleeding episode.

Results

H. pylori-associated bleeding was confirmed in 64.1% (109/170) of the patients. At the bleeding episode, the diagnostic sensitivities of RUT, histology, and DPO-PCR test were 47.7% (52/109), 71.6% (78/109) and 97.2% (106/109), respectively (p < 0.01). The specificity of the DPO-PCR test was 91.8% (56/61). The positive predictive value (PPV) of the DPO-PCR test was 95.5% (106/111), and its negative predictive value (NPV) was 94.9% (56/59).

Conclusions

In patients with PUB, the DPO-PCR test could be a useful diagnostic tool for H. pylori infection. Particularly given a negative RUT result, subsequent DPO-PCR testing of tissue samples from the CLO®test kit could be of considerable benefit.

Introduction

Peptic ulcer bleeding (PUB) is the most frequent source of gastrointestinal bleeding and is associated with high morbidity, mortality, and medical care costs. Among patients who present with PUB, approximately one-third will develop recurrent bleeding within the subsequent 1–2 years, and 40–50% within 10 years if the underlying Helicobacter pylori (H. pylori) infection is left untreated following healing of the primary ulcer [1]. A reliable diagnosis is crucial for patients with H. pylori-related PUB. However, the prevalence of H. pylori infection in PUB appears to be underestimated [2], [3], [4].

At present, the rapid urease test (RUT) and histologic examination are the most common methods for detecting H. pylori-associated PUB in the clinical setting. However, high false-negative rates with these diagnostic strategies have been reported [2], [3], [4], [5], [6]. If the initial diagnostic test for H. pylori is negative, a delayed test 4–8 weeks later is often recommended as a follow-up examination [7]. However, additional endoscopic procedures with biopsies would be burdensome to both clinicians and patients and lead to increased healthcare-related costs.

Polymerase chain reaction (PCR) is the most sensitive and specific method for detecting H. pylori in gastric biopsy specimens. It has high sensitivity with a detection limit of 0.02 pg H. pylori DNA, which corresponds to only 10 organisms [8], [9], [10], [11], [12]. A commercial, dual-priming oligonucleotide (DPO) primer has been developed to detect single-nucleotide polymorphisms using a one-step PCR assay [13], [14], [15], [16]. This approach is less complicated and cheaper than other PCR methods with no requirement for additional technical or expensive detection devices. Detection is accurate and rapid using specific primers. Moreover, DPO-PCR can provide information about clarithromycin resistance, the main predictor of failure of eradication treatment [13]. A recent study demonstrated that the DPO-PCR test using tissue samples processed by the RUT (CLO®test) kit is appropriate for detecting H. pylori and clarithromycin resistance [16].

We investigated the diagnostic yield of the DPO-PCR test using tissue samples from the RUT kit to diagnose H. pylori infection in patients with PUB.

Section snippets

Subjects

We prospectively enrolled patients referred to the endoscopy unit due to objective evidence of upper gastrointestinal bleeding (hematemesis, melena or blood in nasogastric aspirates) at a teaching hospital of the Catholic University of Medicine, St. Vincent's Hospital, from January 2012 to January 2014. Patients were eligible for the study if they were older than 18 years and had a gastric and/or duodenal ulcer as the cause of upper gastrointestinal bleeding. None of the patients had a history

Basal characteristics of the enrolled patients

All patients presented with objective evidence of upper gastrointestinal bleeding (hematemesis, melena or blood in nasogastric aspirates). A total of 180 patients underwent an emergency esophagogastroduodenoscopy within 24 h of initial presentation. All patients had received proton pump inhibitor (PPI) intravenously before second look endoscopy (pantoprazole sodium; Pantoloc®, 80–240 mg). Individuals with conditions that might have a history of gastrectomy (n = 2) and bleeding associated with

Discussion

Although there is no definite explanation for the reduced accuracy of H. pylori diagnostic tests in cases of PUB, several hypotheses have been proposed. First, PPI use before endoscopy [19]; second, a direct bactericidal effect of plasma [20] third, the buffering effect of albumin [21]; fourth, the large volume of gastric lavage prior to endoscopy [22]; fifth, the fact that intragastric air infusion during nasogastric tube placement could alter the microaerophilic gastric environment necessary

Conflicts of interest

None declared.

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