Diagnosis of Helicobacter pylori Infection in a Routine Testing Workflow: Effect of Bacterial Load and Virulence Factors.

Nabil Gastli,Vered Abitbol,Dominique Lamarque,Nicolas Kalach,Josette Raymond,Margaux Allain,Romain Coriat,Gislène Collobert,Benoit Terris,Annick Billoët

doi:10.3390/jcm10132755

Abstract

Reliable diagnostic methods are mandatory for effective management of Helicobacter pylori infection. Histology and culture are the most common invasive methods in current practice, even if molecular methods are gaining in importance. The performance of these conventional methods varies significantly. We conducted a retrospective study of 1540 adults and 504 children with gastric biopsies taken during endoscopy to assess the impact of bacterial load and the cagA virulence factor on the performance of H. pylori infection testing. The association between virulence and histology findings was also investigated. With 23S rRNA qPCR confirmed by glmM amplification as the gold standard, culture and histology had lower sensitivity, 74.4% and 73.3%, respectively. However, their sensitivity was enhanced (>90%) in biopsies with high bacterial load (qPCR Ct < 30). Positive cagA status of the strain was associated with high bacterial load (94.9%), thus resulting in more frequent positive culture (94.3%) and H. pylori histology detection (91.7%) and more severe lesions on histology (p < 0.001). Conversely, the cagA status of the strains was negative in 110/119 (92.4%) of biopsies with low bacterial load (qPCR Ct < 30), 82/90 (91.1%) with negative H. pylori histology detection and 119/131 (90%) with negative culture findings (p < 0.001). This study highlights the low sensitivity of conventional culture and histology that may lead to false negative diagnosis if used alone. H. pylori quantification associated with cagA genotyping in routine workflow are essential for a sensitive and reliable diagnosis, to identify patients at high risk and to manage eradication therapies.

Highlights

We evaluated the performance of both histology and culture for detecting H. pylori infection, taking as the gold standard molecular techniques (23S rRNA confirmed by glmM)
A real gap may exist between international guidelines and daily practice, with continued use of pump inhibitors (PPIs) at endoscopy or one-region biopsy sampling, which can increase the likelihood of missing active infection by histology [24]
We confirmed that a false negative diagnosis by histology staining may be linked to biopsies with few Helicobacter-like organisms [26], in agreement with the findings of Benoit et al, stating that H. pylori is present only in cases of active gastritis and is always on the standard staining with H-E [27]

Summary

Introduction

Helicobacter pylori infection is related to a wide spectrum of diseases including uncomplicated or complicated ulcer diseases, mucosa-associated lymphoid tissue lymphoma, atrophic gastritis and gastric cancer. The correct management of these severe conditions requires constant collaboration between gastroenterologists, pathologists and biologists. H. pylori infection can be diagnosed by the non-invasive techniques serology, 13C urea breath test and stool antigen test, even if the strategy “test and treat” is no longer recommended. The other approach requires gastric biopsy collection during endoscopy and analysis by urease tests, histopathology, culture and/or molecular detection by PCR [1]. Histology allows for detecting H. pylori and tissue damage and is one of the most commonly used methods. The Maastricht consensus states that most cases can be diagnosed by only histochemical staining of biopsies [2]

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