To stain or not to stain...That remains the question

Helicobacter pylori Infection, Its Laboratory Diagnosis, and Antimicrobial Resistance: a Perspective of Clinical Relevance

Despite the recent decrease in overall prevalence of Helicobacter pylori infection, morbidity and mortality rates associated with gastric cancer remain high. The antimicrobial resistance developments and treatment failure are fueling the global burden of H. pylori-associated gastric complications. Accurate diagnosis remains the opening move for treatment and eradication of infections caused by microorganisms. Although several reports have been published on diagnostic approaches for H. pylori infection, most lack the data regarding diagnosis from a clinical perspective. Therefore, we provide an intensive, comprehensive, and updated description of the currently available diagnostic methods that can help clinicians, infection diagnosis professionals, and H. pylori researchers working on infection epidemiology to broaden their understanding and to select appropriate diagnostic methods. We also emphasize appropriate diagnostic approaches based on clinical settings (either clinical diagnosis or mass screening), patient factors (either age or other predisposing factors), and clinical factors (either upper gastrointestinal bleeding or partial gastrectomy) and appropriate methods to be considered for evaluating eradication efficacy. Furthermore, to cope with the increasing trend of antimicrobial resistance, a better understanding of its emergence and current diagnostic approaches for resistance detection remain inevitable.

Comparison of Different Histological Staining Methods for Detection of Helicobacter pylori Infection in Gastric Biopsy

Background: Helicobacter pylori gastritis affects two-thirds of the world's human population. Among various invasive and non-invasive tests, histology play a very important role in detecting H. pylori in gastric biopsies. In histology, for detection of H. pylori, we use different histological staining techniques like routine haematoxylin & eosin (H&E) stain, Giemsa stain, Gimenez stain, and periodic acid Schiff - Alcian blue (PAS-AB) stain.

Objective: Aim of our study was to evaluate these different histopathological staining techniques for detecting H. pylori in gastric mucosal biopsies and to determine the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of H&E stain, Gemenez stain and PAS-AB in the detection of H. pylori in gastric biopsies using Giemsa stain as the reference standard.

Materials and Methods: It was a prospective descriptive study design of 45 gastric biopsies of patients having gastritis. This study was conducted at Vivekananda Polyclinic and Institute of Medical Sciences over a period of one year, from March 2021 to February 2022. From each formalin-fixed paraffin-embedded block, four glass slides were prepared and stained with H&E stain, Giemsa stains, Gemenez stain, and PAS-AB stain to detect the presence/absence of H. pylori in gastric biopsies. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were assessed.

Results: Various staining techniques for detecting H. pylori in gastric mucosal biopsies were compared. In reference to Giemsa stain results, statistical analysis indicates that the diagnostic accuracy of the Gimenez stain, H&E stain, and PAS-AB stain were 95.6%, 91.1%, and 84.4% respectively. Gimenez stain is confirmed to be better than H&E stain and PAS-AB stain to detect H. pylori in 45 gastric biopsies of patients having gastritis. PAS-AB stain is the worst stain to detect H. pylori in gastric biopsies.

Conclusion: Gimenez stain has higher diagnostic accuracy than PAS-AB stain in the detection of H. pylori in gastric biopsy. In fact, Gimenez stain has high sensitivity, specificity and diagnostic accuracy as compared to traditional H&E stain while PAS-AB stain has lower sensitivity, specificity and diagnostic accuracy. Thus, Gimenez stain is also recommended for the detection of H. pylori in gastric biopsy.

Sensitivity of Helicobacter pylori detection by Giemsa staining is poor in comparison with immunohistochemistry and fluorescent in situ hybridization and strongly depends on inflammatory activity

BACKGROUND

Conventional stainings (including H&E and special stains like Giemsa) are the most widely applied histopathologic detection methods of Helicobacter pylori (HP).

MATERIALS AND METHODS

We aimed to compare the diagnostic performance of Giemsa staining with immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) on a monocentric cohort of 2896 gastric biopsies and relate results to histologic alterations in order to find such histopathologic subgroups in which these methods underperform. All cases were categorized regarding presence or absence of chronic gastritis, inflammatory activity, and mucosal structural alterations.

RESULTS

Giemsa revealed 687 cases (23.7%), IHC 795 cases (27.5%), and FISH 788 cases (27.2%) as being HP positive. Giemsa showed significantly lower overall sensitivity (83.3%) compared to IHC (98.8%) and FISH (98.0%). Moreover, the sensitivity of Giemsa dramatically dropped to 33.6% in the nonactive cases. We found that sensitivity of Giemsa strongly depends on HP density and, accordingly, on the presence of activity. Structural alterations (intestinal metaplasia, atrophy, etc.) had only no or weak effect on sensitivity of the three stainings. Both IHC and FISH proved to be equally reliable HP detecting techniques whose diagnostic performance is minimally influenced by mucosal inflammatory and structural alterations contrary to conventional stainings.

CONCLUSIONS

We highly recommend immunohistochemistry for clinically susceptible, nonactive chronic gastritis cases, if the conventional stain-based HP detection is negative. Moreover, we recommend to use IHC more widely as basic HP stain. Helicobacter pylori FISH technique is primarily recommended to determine bacterial clarithromycin resistance. Furthermore, it is another accurate diagnostic tool for HP.

Helicobacter infections with rare bacteria or minimal gastritis: Expecting the unexpected

BACKGROUND

The routine use of special stains for detection of Helicobacter remains controversial.

AIMS

To determine the frequency of histologically atypical Helicobacter infection.

METHODS

All gastric biopsies received at a large pathology reference laboratory over a 6-month period were stained for Helicobacter, and the histologic and clinicopathologic parameters evaluated.

RESULTS

Amongst 7663 Helicobacter-positive biopsies, 823 (10.7%) did not show typical chronic active gastritis with numerous Helicobacter organisms, and were therefore considered histologically atypical. Rare Helicobacter pylori organisms accounted for 58.0% of all atypical infections; the next most common atypical Helicobacter infection was that with minimal or no gastric inflammation (23.3% of atypical infections). Patients in these groups did not differ demographically from those with other forms of atypical or typical Helicobacter infection, although a small subgroup (6%) was more likely to have had a previously treated infection.

CONCLUSIONS

In many of these atypical infections, Helicobacter would not have been suspected based on the histologic findings alone, and would have been missed without routine special stains. Performing a sensitive stain could prevent additional testing and allow prompt treatment of the affected patients, thus substantially reducing the risk for peptic ulcer and gastric cancer and preventing the transmission of the infection to family members.

Upfront special staining for Helicobacter pylori in gastric biopsy specimens is not indicated

OBJECTIVES

The practice of routine upfront use of special stains in biopsy specimens with minimal or no inflammation has not been evaluated. This study was conducted to determine the value of special stains for Helicobacter pylori in gastric biopsy specimens showing variable degrees of inflammation and to evaluate the practice of upfront ancillary staining of all mucosal biopsy specimens.

METHODS

Immunohistochemical or Diff-Quik stains were done on sections of 570 gastric biopsy specimens. The rates of positivity for H pylori were calculated in each category based on the degree of inflammation and classified as normal, minimal, mild, moderate, or severe.

RESULTS

H pylori was not detected in 386 (67.7%) biopsy specimens that were classified as normal (6.0%) or with minimal inflammation (28.2%) or mild inactive gastritis (33.5%). The organism was identified by Diff-Quik or immunohistochemical stain in 76 (89.4%) of 85 with moderate active gastritis and 30 (93.8%) of 32 biopsy specimens showing severe active gastritis.

CONCLUSIONS

Upfront staining of gastric biopsy specimens is not cost-effective since a significant proportion of the gastric biopsy specimens were normal or showed minimal inflammation; in none of these biopsy specimens was the organism found. Special stains should be performed only in selected biopsy specimens that reveal any degree of chronic active gastritis or moderate inactive gastritis.