HELICOBACTER PYLORI associated

GIT disorders

20-05-2014

Dr. Niraj GuptaM.R.M.C.,Gulbarga

• Introduction• Epidemiology• Mode of transmission• Risk factors• Spectrum of diseases• Virulence factors• Pathogenesis• Gastric and Extra-gastric conditions (related)• Diagnosis • Treatment and Eradication• Summary• References

Introduction• In 1982-83, Warren and Marshall from australia, described a

spiral organism which colonizing human stomach- called as H. pylori.

• In recognition of their very important discovery, they were Awarded the 2005 Nobel Prize for Medicine & Physiology.

• Helicobacter spp. are spiral-shaped or curved, gram-negative, non–sporeforming bacilli, measuring 0.3–1.0 μm wide and 1.5–10 μm long.

• They are motile by multiple bipolar or monopolar flagella, are microaerobic, and have a respiratory metabolism.

• Helicobacter pylori is considered to be one of the “gastric” helicobacters.

• In the stomach, it lives within or beneath the mucous layer adjacent to the epithelium. It is also found transiently in the duodenum,saliva, and feces.

Epidemiology

• The prevalence of H. pylori varies throughout the world and depends largely on the overall standard of living in the region.

• In developing parts of the world, 80% of the population may be infected by the age of 20, whereas the prevalence is 20–50% in developed countries.

• In developing countries more common in children (in the United States this organism is rare in childhood).

Mode of Transmission

• Feco-oral route• Oral-oral• Gastro-oral

Risk factors

• Low socio-economic status• Less education• Domestic crowding• Poor hygiene• Unsanitary living conditions• Unclean food and Water • Exposure to gastric contents of an infected

individual.

Spectrum of H. pylori

• Gastric conditions– Gastritis– Peptic ulcer disease– Gastric

adenocarcinoma– Gastric lymphoma– Intestinal

metaplasia– Chronic Duodenitis

• Extra gastric conditions– Vascular conditions– Skin diseases– Respiratory

diseases– Autoimmune

disease– Others

Pathogenesis

• H pylori grows optimally at a pH of 6.0–7.0 and would be killed or not grow at the pH within the gastric lumen.

• Gastric mucus is relatively impermeable to acid and has a strong buffering capacity.

• On the lumen side of the mucus, the pH is low (1.0–2.0) while on the epithelial side the pH is about 7.4.

• H pylori is found deep in the mucous layer near the epithelial surface where physiologic pH is present.

• Corkscrew like bacterial movement(via flagella) and enzyme production are important early in the infection.

• Bacterial proteases digest gastric mucin facilitating bacterial movement and urease protects the HP from the luminal acid by creating an alkaline microenvironment , by yielding ammonia) around the bacterium.

• H pylori is quite motile, even in mucus, and is able to find its way to the epithelial surface.

• The particular end result of H. pylori infection (gastritis, PUD, gastric MALT lymphoma, gastric cancer) is determined by a complex interplay between bacterial and host factors.

Bacterial factors• H. pylori is able to facilitate gastric residence, induce

mucosal injury, and avoid host defense.• Different strains of H. pylori produce different virulence

factors. • A specific region of the bacterial genome, the pathogenicity

island (cag-PAI), encodes the virulence factors Cag A and pic B.

• Vac A also contributes to pathogenicity, although it is not encoded within the pathogenicity island.

• These virulence factors, in conjunction with additional bacterial constituents, can cause mucosal damage, in part through their ability to target the host immune cells.

• For example, Vac A targets human CD4 T cells, inhibiting their proliferation and in addition can disrupt normal function of B cells, CD8 T cells, macrophages and mast cells.

• Multiple studies have demonstrated that H. pylori strains that are cag-PAI positive are associated with a higher risk of peptic ulcer disease, premalignant gastric lesions and gastric cancer than are strains that lack the cag-PAI.

• Motility via flagella- allow the organism to move quickly from the lumen of the stomach where PH is low.

• Urease, which allows the bacteria to reside in the acidic stomach, generates NH3, which can damage epithelial cells.

• The bacteria produce surface factors that are chemotactic for neutrophils and monocytes, which in turn contribute to epithelial cell injury .

• Vacuolating cytotoxin (Vac A) positive strains results in:– Cyoplasmic swelling– Vacuolization– Micropapillary

changes– Loss of mucin– Desquamation of

surface foveolar cells

• Cytotoxin associated antigen (Cag A) positivity results in:– Host growth factor

(cellular response)– Disruption of apical

junctional complexes– Epithelial cell

apoptosis

• H. pylori makes proteases and phospholipases that break down the glycoprotein lipid complex of the mucous gel, thus reducing the efficacy of this first line of mucosal defense.

• H. pylori expresses adhesins (OMPs like BabA), which facilitate attachment of the bacteria to gastric epithelial cells.

• Although lipopolysaccharide (LPS) of gram-negative bacteria often plays an important role in the infection, H. pylori LPS has low immunologic activity compared to that of other organisms. It may promote a smoldering chronic inflammation.

Host factors• The inflammatory response to H. pylori includes

recruitment of neutrophils, lymphocytes (T and B), macrophages, and plasma cells.

• The pathogen leads to local injury by binding to class II major histocompatability complex (MHC) molecules expressed on gastric epithelial cells, leading to cell death (apoptosis).

• Moreover, bacterial strains that encode cag-PAI can introduce Cag A into the host cells, leading to further cell injury and activation of cellular pathways involved in cytokine production.

• Elevated concentrations of multiple cytokines are found in the gastric epithelium of H. pylori–infected individuals, including interleukin (IL) 1/, IL-2, IL-6, IL-8, tumor necrosis factor (TNFα) , and interferon (IFN-γ).

• H. pylori infection also leads to both a mucosal and a systemic humoral response, which does not lead to eradication of the bacteria but further compounds epithelial cell injury.

• Additional mechanisms by which H. pylori may cause epithelial cell injury include

(1) activated neutrophil-mediated production of reactive oxygen or nitrogen species and enhanced epithelial cell turnover and

(2) apoptosis related to interaction with T cells (T helper 1, or TH1, cells) and IFN-γ.

Gastritis• HP bacteria preferentially colonize the antrum, but they

may infect any part of the stomach where they cause gastritis. When treated, the bacteria migrate from the antrum to the corpus with decreasing activity of the antral gastritis.

• Four features are linked to H. pylori virulence:– Flagella: allows bacteria to be motile– Urease: allows bacteria to reside in acidic

medium and generates ammonia which can damage epithelial cells.

– Toxins: cytotoxin associated gene A and vacuolating cytotoxin gene

– Adhesins: enhance bacterial adherence.

Results of an imbalance between gastroduodenal mucosal defenses

and damaging forces that overcome those defenses.

increased acid production and disruption of normal gastric and duodenal protective mechanism.

• an antral biopsy is preferred for evaluation of H. pylori gastritis.

• When viewed endoscopically, H. pylori infected antral mucosa is usually erythematous and has a coarse or even nodular appearance.

• The inflammatory infiltrate generally includes variable numbers of neutrophils within the lamina propria, In addition, the superficial lamina propria includes large numbers of plasma cells, often in clusters or sheets, and increased numbers of lymphocytes and macrophages.

• Intraepithelial neutrophils and subepithelial plasma cells are characteristic of H. pylori gastritis.

• Marked neutrophilic infiltrates appear in the mucous neck region and lamina propria in early acute gastritis; when severe, they aggregate in the pit lumens to form pit abscesses.

• The mucosa appears normal in thickness or even slightly expanded due to the lymphoplasmacytic cell infiltrate in the superficial lamina propria.

• At this point the lesion can be termed chronic active gastritis or active chronic gastritis.

• Organisms are most easily demonstrated with a variety of special stains .

Fig.: Spiral-shaped H. pylori are highlighted in this Warthin-Starry silver stain.

• Acute H. pylori infection does not produce sufficient symptoms to require medical attention in most cases; it is the chronic gastritis that ultimately causes the individual to seek treatment.

• H. pylori organisms are present in 90% of individuals with chronic gastritis affecting the antrum.

• Both the neutrophils and the HP destroy the epithelium, causing the mucous neck cells to proliferate in an effort to replace the dying cells.

• Other changes in severe infections include epithelial cell dropout, microerosions, larger erosions, and ulcers.

• Erosions forming in the setting of HP infections typically lack the homogeneous eosinophilic necrosis seen in patients with stress ulcers or aspirin- or NSAID-related ulcers.

• Chronic superficial gastritis progresses to the next stage, chronic atrophic gastritis, over a period of 15 to 20 years .

• Chronic gastritis develops as a patchy process, with time, the inflammation becomes confluent until it occupies the full thickness of the mucosa.

• T cells increase in number in both the epithelium and the lamina propria.

• Neutrophils, eosinophils, basophils, B cells, macrophages, monocytes, plasma cells, and mast cells infiltrate the mucosa resulting in mucosal damage.

• When the infection is treated, the mucosa regenerates and returns to normal; if the destroyed glands fail to regenerate, the space that they previously occupied in the lamina propria may be replaced by fibroblasts and extracellular matrix leading to an irreversible loss of functional mucosa and a change diagnosable as atrophy .

• The degree of atrophy can be graded as mild, moderate, or severe by estimating the thickness of the glands in relationship to the entire mucosal thickness.

• This is facilitated by examining properly oriented biopsies containing the muscularis mucosae. Increasing degrees of atrophy associate with glandular cystic dilation, epithelial atypia, and intestinal metaplasia.

• Loss of all the glands qualifies for the diagnosis of severe atrophic gastritis.

• As atrophy develops, areas of intestinal metaplasia replace the native gastric mucosa.

• This may represent an adaptive response because HP bacteria cannot colonize the metaplastic cells since they lack the necessary bacterial adhesion factors .

• These cells in fact represent a hybrid epithelium whose cells share characteristics of both gastric surface mucous cells and intestinal metaplastic cells .

• The intestinal metaplasia decreases the sites hospitable to the growth of the HP. However, the inflammation and its associated reparative processes continue in sites of persisting infection.

• As a result, the stomach acquires a mixed pattern of architecturally normal but inflamed areas (gastritis) alternating with expanding patches of atrophy and metaplasia producing multifocal atrophic gastritis (MAG) .

:

• Lymphoid aggregates appear and sometimes lymphoid follicles develop. These are located deep in the mucosa, near the muscularis mucosae.

• When lymphoid follicles develop, with or without follicular centers , the lesion is termed follicular gastritis .

• Antral lymphoid follicles can become quite prominent, sometimes causing mucosal nodularity, especially in children .

• The lymphoid aggregates represent an immune response to the bacteria.

• Their presence provides a useful marker for HP infections.

• Granulomatous gastritis develops in approximately 1% of HP-infected patients, usually in patients with small numbers of organisms.

• The small sarcoid-type granulomas lie in the gastric lamina propria and HP bacteria can sometimes be found within them.

• The granulomas develop late in the disease, after the host has become sensitized to the organism.

Peptic ulcer disease• Peptic ulcer disease (PUD) is most often associated with H.

pylori induced hyperchlorhydric chronic gastritis, which is present in 85% to 100% of individuals with duodenal ulcers and in 65% with gastric ulcers.

• PUD may occur in any portion of the GI tract exposed to acidic gastric juices, but is most common in the gastric antrum and first portion of the duodenum.

• Imbalances of mucosal defense and damaging forces that causes chronic gastritis are responsible for PUD.

• Urease and other factors produced by the HP break the mucosal barrier, allowing ulcers to develop.

• Not all HP infections lead to ulcer development. • VacA- and CagA-positive HP are more likely to

produce peptic ulcers than VacA- and CagA-negative HP

• Specifically, colonization with vacA2m2/cag A-positive HP strains correlates with peptic ulcer disease (PUD).

• Although H. pylori does not invade the tissues, it induces an intense inflammatory and immune response.

• There is increased production of pro-inflammatory cytokines such as interleukin (IL)-1, IL-6, tumor necrosis factor (TNF), and, most notably, IL-8. This cytokine is produced by the mucosal epithelial cells, and it recruits and activates neutrophils.

• Several bacterial gene products are involved in causing epithelial cell injury and induction of inflammation.

Pathogenesis

• H.pylori secretes a urease that breaks down urea to form toxic compounds such as ammonium chloride and monochloramine. The organisms also elaborate phospholipases that damage surface epithelial cells.

• Bacterial proteases and phospholipases break down the glycoprotein-lipid complexes in the gastric mucus, thus weakening the first line of mucosal defense.

• H. pylori enhances gastric acid secretion and impairs duodenal bicarbonate production, thus reducing luminal pH in the duodenum.

• This altered milieu seems to favor gastric metaplasia (the presence of gastric epithelium) in the first part of the duodenum. Such metaplastic foci provide areas for H. pylori colonization.

• Several H. pylori proteins are immunogenic, and they evoke a robust immune response in the mucosa.

• Both activated T cells and B cells can be seen in chronic gastritis caused by H. pylori. The B lymphocytes aggregate to form follicles.

• The role of T and B cells in causing epithelial injury is not established, but T-cell-driven activation of B cells may be involved in the pathogenesis of gastric lymphomas.

• Thrombotic occlusion of surface capillaries is promoted by a bacterial platelet-activating factor.

• Other antigens (including lipopolysaccharide) recruit inflammatory cells to the mucosa. The chronically inflamed mucosa is more susceptible to acid injury.

• Damage to the mucosa is thought to permit leakage of tissue nutrients into the surface microenvironment, thereby sustaining the bacillus.

Role in gastric acid secretions

• H. pylori infection elevates levels of gastrin.• H. pylori’s effects on gastrin and acid are likely

mediated through somatostatin, a peptide produced by antral D cells.

• Somatostatin, which serves as the ‘‘brake’’ for gastrin secretion, seems to be up-regulated or downregulated as a result of the severity and distribution of H. pylori-associated inflammation.

• Eradication of the bacterium causes gastrin levels to return to normal.

Clinical Presentation

• The majority of peptic ulcers come to clinical attention because of epigastric burning or aching pain, although a significant fraction present with complications such as iron deficiency anemia, frank hemorrhage, or perforation.

• The pain tends to occur 1 to 3 hours after meals during the day, is worse at night, and is relieved by alkali or food.

• Nausea, vomiting, bloating, belching, and significant weight loss are additional manifestations.

• Gastric peptic ulcers are predominantly located along the lesser curvature near the interface of the body and antrum.

• Duodenal ulcers usually occur within a few centimeters of the pyloric valve and involve the anterior duodenal wall.

• Peptic ulcers are solitary in more than 80% of patients.

• The classic peptic ulcer is a round to oval, sharply punched-out defect .

• In contrast, heaped-up margins are more characteristic of cancers.

Benign ulcer

Malignant ulcer

• Four zones characterize chronic ulcers: (1) polymorphonuclear leukocytes, (2) coagulation necrosis, (3) granulation tissue, and (4) fibrosis of the ulcer base

Gastric cancer• First incriminated as a cause of peptic ulcers, H.

pylori now has been acquired the dubious distinction being the first bacterium classified as carcinogen.

• H. pylori has been classified as a class I human carcinogen by the International Agency for Research on Cancer of the World Health Organization.

• Development of AdenoCa Involves increased epithelial cell proliferation in background of chronic inflammation followed by gastric atrophy, intestinal metaplasia, dysplasia and cancer.This sequence takes decades to complete.

The Correa Cascade

• Gastric cancer patients are more likely to have the IL-1B-31T/IL-1RN phenotype.

• Genetic variants of pro-inflammatory and immune response genes, including those that encode IL-1β,TNF, IL-10, IL-8, and Toll-like receptor 4 (TLR4), are associated with elevated risk of gastric cancer when accompanied by H. pylori infection.

• Prospective studies have shown a consistent association between the presence of distal gastric cancer and high antibody levels against H. pylori.

• When compared to other H. pylori strains, the cagA strain is associated with heightened antibody levels, a more robust inflammatory response, and a higher risk of gastric cancer.

One mechanism by which H. pylori infection may increase stomach cancer risk is through exposure of replicating cells to reactive oxygen species derived from the inflammatory cells that are part of H. pylori gastritis.

Fig. Mechanisms by which Helicobacter pylori increases gastric cancer risk.

• Most gastric adenocarcinomas involve the gastric antrum; the lesser curvature is involved more often than the greater curvature.

• Four growth patterns are recognized: Polypoid, fungating, ulcerated, and infiltrating.

Intestinal type Musinous type (signet ring)

The MALT concept

• The distribution of GIT lymphomas is paradoxic since the normal gastric mucosa is almost devoid of lymphoid tissue.

• Many primary intestinal lymphomas arise proximal to the terminal ileum, where there is greatest conc. of mucosa(gut) associated lymphoid tissue [MALT] in the form of peyer patches.

Gastric Lymphoma

• MALT lymphoma is listed in the WHO classification under the designation “extranodal marginal zone lymphoma of mucosa associated lymphoid tissue”(MALT lymphoma).

• Defined as lymphoma that recapitulates the histology of MALT (peyer patch); the normal counterpart is the marginal zone B cell.

• It comprises of 7-8% of all B cell lymphoma and atleast 50% of primary gastric lymphoma.

• Several lines of evidence suggest that gastric MALT lymphoma arises from MALT acquired as a consequence of h. pylori infection.

• The most striking evidence linking H. pylori gastritis to MALToma is that eradication of the infection with antibiotics induce durable remissions with low rates of recurrneces in most patients.

• Series of in vitro studies showing that lymphoma growth could be stimulated in culture by H. pylori strain “specific T cells when crude lymphoma cultures were exposed to the organism.

• H. pylori can be demonstrated in the gastric mucosa of the majority of cases of gastric MALT lymphomas

• Biopsy from a gastric MALT lymphoma showing a characteristic lymphoepithelial lesion (left) containing Helicobacter pylori (right).

• Genetics :

• 3 translocations are associated with gastric MALTomas– t(11;18) (q21;q21)– t(1;14) (q22;q32)– t(14;18) (q32;q21

• API 2 gene on chromosome 11 + MALT gene on chromosome18.

(API 2-MALT fusion protein)

• Causes increased expression of intact MALT1 and BCL10 proteins respectively.

• The oncogenic activities of the three chromosome translocations are linked by the physiologic role of BCL10 and MALT1 in antigen receptor-mediated nuclear factor (NF) κB activation

• In MALTomas that lack these translocations, H. Pylori induced inflammation may trigger NF-κB activation through MALT1/BCL-10 pathway.

• In these tumors, elimination of immune stimulus down regulates NF-κB resulting in tumor regression.

Gastric MALToma and H. pylori gastritis often co-exists. They have overlapping clinical symptoms & endoscopic appearnces.

diagnostic difficulties sometimes arise, particularly in small biopsy specimens. Watherspoon et al have proposed scoring system to assist.

Score Interpretation histology

0 Normal Occasional plasma cells

1 Chronic active gastritis Lymphocytes clusters, no follicles

2 Follicular gastritis Prominent follicles, no lymphoepithelial lesion

3 Suspicious, probably reactive

F; occasional lymphoepithelial lesion, no diffuse infiltrates

4 Suspicious, probably lymphoma

F; diffuse marginal zone cell infiltrates, no LE lesion

5 MALT lymphoma +++++ lymphoepithelial lesion

MALT lymphoma

H. Pylori Gastritis

Lymphoid follicles Frequent May be present

Follicular colonization May be present Absent

Inter follicular lymphocytes

Small to intermediate with irregular nucleus

Mature, small and round

B lymphocytes(+ve for CD20)

Predominant; may co-express CD 43

Sparse; don’t co-express CD 43

T lymphocytes(+ve for CD 3)

Variable in number Predominant

Plasma cells Variable Usually prominent

Lympho-epithelial lesion

Usually prominent mainly B cells

Rare and inconspicous mainly T cells

Infiltration of muscularis mucosa by lymphoid cells

May be present Absent

• Detail of the dome epithelium showing intraepithelial B lymphocytes constituting the lymphoepithelium that defines mucosa-associated lymphoid tissue.

• Immunohistochemical findings of gastric marginal zone lymphoma are similar to nodal examples of the disease, and include positivity for CD20, CD79a, CD21, CD35, BCL2 and surface immunoglobulins.

• They are negative for CD5, CD10, CD23, and cyclinD1.

Gastro esophageal reflux disease

• H. pylori and GERD account for most of upper gastrointestinal problems. However, the relationship between H. pylori and GERD remains unclear and study results are conflicting.

• Although testing for and eradication of H. pylori have become standard in the treatment of peptic ulcers, no consensus has been reached on whether this will be advantageous for patients with GERD.

• Some studies have found that eradication of H. pylori was linked with a higher incidence of increased acid production and subsequent reflux symptoms whereas others found that it had no such effect.

Functional Dyspepsia• There is evidence to suggest a role of H. pylori

infection in functional dyspepsia, but a clear association has not been established, and the efficacy of H. pylori eradication treatment for functional dyspepsia is controversial.

• In one review, Chey and Moayyedi reported that H. pylori eradication resulted in small but statistically significant improvements in symptoms in those with uninvestigated and investigated dyspepsia.

• Guidelines from the American Gastroenterological Association and those from several European nations, recommend an H. pylori test-and-treat strategy for young patients with uncomplicated uninvestigated dyspepsia. It is less expensive to test for infection than to refer a patient for endoscopy.

Extra gastric conditions

• Most commonly asst. conditions are ITP and iron deficiency anemia.

• Helicobacter pylori (HP) gastric infection has been implicated as an important factor in occlusive arterial pathology.

• Nowadays, it is suspected that central serous chorioretinopathy (CSC) is due to a multifocal vascular occlusive disease of the choriocapillaris. (ARCH SOC ESP OFTALMOL 2008; 83)

Diagnosis of H.pylori

• Clinically symptoms can vary in nature and severity between individuals.

• In gastritis and peptic ulcer- epigastric pain and burning in the upper abdomen can present.

• Other symptoms can include nausea, vomiting and pain between the shoulder blades in the back.

• The pain of a peptic ulcer often begins about two hours after eating and also occurs at night. Eating more food or taking an antacid often decreases or relieves the pain.

Noninvasive test• In patients who do not require endoscopic evaluation for

evaluation of new onset dyspepsia (those under age 55 who do not have alarm symptoms), initial diagnosis of Helicobacter pylori should be made with a test for active infection (stool antigen or urea breath test).

• Criteria for choosing an H. pylori test in the primary care setting :

1. Non-invasive testing should be limited to H. pylori tests that detect active infection only. Tests for active infection include:

The HpSA® stool antigen test Urea breath test (UBT) • The American Gastroenterological Association no longer

recommends serologic antibody testing either for primary diagnosis or to confirm eradication of H. pylori.

• Serologic antibody tests do not distinguish between currently active infection with a past exposure or an infection that has been cured.

2. Testing should precede treatment. Antibiotics should not be prescribed without testing for H. pylori infection first.

3. Testing should only be performed in patients who will be administered treatment upon a positive result.

Criteria for the ideal Helicobacter pylori test in primary care

• Accurate diagnostic for active infection • Sensitivity and specificity >90% • Positive and negative predictive values >90% • Immediate availability in-office or clinical laboratory • Rapid turnaround • Inexpensive • Convenient for physician and patient • Harmless • Unaffected by immunological response

HpSA stool antigen test

• H. pylori antigen testing of human stool by enzyme immunoassay or immunochromatography (HpSA®) is one of the simplest and least expensive methods available. HpSA:

Detects active infection with a sensitivity and specificity exceeding 90%;

Has been approved for all ages; Is less affected by concomitant PPI use, and Is effective during the continuum of therapy.

• Results of the stool antigen test aid in the definitive diagnosis of active H. pylori infection, can be used to monitor response during and after treatment, and can confirm eradication of H. pylori.

• Confirmation of eradication should be performed 1 month after eradication therapy has been completed.

Urea breath test (UBT)

• The Urea Breath Test (UBT) measures radio-labeled carbon dioxide released through the breath when urease, the enzyme produced by H. pylori, breaks down a sample of C13- or C14-labeled urea. The UBT:

Is indicated for patients 18 years of age or older and should be administered by trained office staff

Requires that the patient ingest a standard sample of labeled C13 or C14 and, at a predetermined time, produce a breath sample

Requires a mass spectrometer or scintillation counter Patients are required to be off the following medications. Proton

Pump inhibitors, Bismuths, and antimicrobials two weeks prior to being tested.

Patient procedure requires that the patient ingest a citric solution that contains Phenylalanine.

(If H. pylori is absent, the 14C-urea is simply absorbed and subsequently voided)

UBT test principle

1.Patient swallows a

labeled C13/14 urea

tablet. Dissolves to

release 14C-urea.

2.If present, H. pylori

metabolizes 14C-urea to

labeled carbon dioxide

(14CO2) and ammonia via

the enzyme urease.

3.14CO2 is transported in

the blood to the lungs.

4.Patient exhales. 14CO2 is

captured for analysis.

H2N(13/14CO)NH2 + H20 →

urease → 2NH3 + 13/14CO2

Analyzer

Serologic antibody testing

• Historically, serologic assay for immunoglobulin G (IgG) antibodies to H. pylori by (ELISA) testing had been recommended for screening prior to therapy.

• However due to its high rate of false positives and false negatives, it is no longer reliable for use in primary care settings.

• Serologic antibody tests do not distinguish between currently active infection with a past exposure, or an infection that has been cured, because the test remains positive for years even if the infection is cured.

• The American Gastroenterological Association no longer recommends serologic antibody testing either for primary diagnosis, or to confirm eradication of H. pylori.

Invasive Testing

• Invasive testing methods (i.e. histology, rapid urease testing, and culture) are based on endoscopy and biopsy.

• These techniques are reserved for patients who require endoscopy because of alarm signs or who have new symptoms that develop after the age of 50 years.

• For other patients who have ulcer-like dyspepsia or other gastrointestinal signs and symptoms that suggest H. pylori infection or PUD, initial noninvasive testing is appropriate.

“alarm features”

• Bleeding• Anaemia• Early satiety• Unexplained weight loss• Progressive dysphagia• Odynophagia• Recurrent vomiting• Family history of gastrointestinal cancer• Previous esophagogastric malignancy.

• Endoscopy is an accurate test for diagnosing H. pylori as well as the inflammation and ulcers that it causes.

• Main indications of these tests to check healing and to exclude underlying gastric cancer and occasionally in follow up.

• During endoscopy, small tissue samples (biopsies) from the stomach lining can be removed.

• Minimum of two biopsies are required because of the Patchy nature of infection;

• One from antrum• One from fundus

• A biopsy specimen is placed on a special slide containing urea (e.g., CLO test slides).

• If the urea is broken down by H. pylori in the biopsy, there is a change in color around the biopsy on the slide. This means that there is an infection with H. pylori in the stomach.

Sensitivity=89-98%Specificity=93-98%

Rapid urease test

Stains which can be used for detection of organism

• H & E• Giemsa • Diff-quik• Steiner(silver stain)• Warthin starry(silver stain)• Alcian blue• Genta(triple stain)• Acridine orange• Immunostain(H. pylori monoclonal antibody )

• H. pylori are tiny (2–5 μm) organisms that may appear slightly basophilic within the mucus layer on H&E staining.

Giemsa stain

• Modified Diff-Quik stain shows blue H. pylori against a lighter blue background in a gastric cardia biopsy.

Genta or triple stain combines a Steiner silver impregnation stain, H&E, and Alcian blue pH 2.5.

Warthin starry(silver stain)

Immunostain(H. pylori monoclonal antibody)

Spiral formCoccoid form

• It is possible to culture Helicobacter pylori from biopsy specimens, although it should be stated that this is not a routine procedure.

• Culture is not routinely used for initial diagnosis. • Culture is necessary for susceptibility testing if treatment

failure is suspected. • Cultures from stomach biopsies for H.pylori are grown on

enriched mediums (Brucella agar supplemented with 5% horse blood, or brain heart infusion media with 7% horse blood , under microaerobic conditions (90% N2, 5% CO2, and 5% O2) for three to four days. – Appears curved or spiral shaped.– Fresh: spiral shaped; older: coccoid form– Coccoid form appears as solid, round

basophilic, dot like structure

Culture: (Sensitivity=77-92%), ( Specificity=100%)

Strongly recommended indications for H. pylori eradication therapy

• Peptic ulcer disease• MALT lymphoma• Atrophic gastritis• Post gastric ca resection• Unexplained IDA• In some cases of ITP

Summary

• H. pylori persistently colonizes the stomach of almost more than 50% of world’s human population and is main risk factor for peptic ulceration as well as gastric adenocarcinoma and gastric MALT lymphoma.

• Different invasive and noninvasive diagnostic facilities are available.

• Eradication of H.pylori is possible by proper therapy.• Rising antibiotic resistance increases the need to

search for new therapeutic strategies; this might include prevention in form of vaccination.

• Much work has been done on developing viable vaccines aimed at providing an alternative strategy to control H. pylori infection and related diseases, including stomach cancer.

• However, most of the research only recently moved from animal to human trials.

References• Fenoglio-Preiser , Cecilia M. Noffsinger, Amy E.Stemmermann,

Grant N., Patrick E., Peter G.. Gastrointestinal Pathology: An Atlas and Text. 3rd Edition. 2008. Lippincott Williams & Wilkins.

• Christine A. Iacobuzio-Donahue, MD, PhD and Elizabeth A. Montgomery, MD . Gastrointestinal and Liver Pathology. 2nd Edition. 2012. Elsevier.

• Kumar, Abbas, Fausto, Aster. Robbins and Cotran Pathologic Basis of Disease; 8th edition; 2010; Saunders Elsevier.

• Laura W. Lamps. Surgical Pathology of the Gastrointestinal System: Bacterial, Fungal, Viral and Parasitic Infections. Springer.

• Various Internet references.

Thank you