Priyadharshini, M (2012) Role of Immunohistochemistry Versus Hematoxylin & Eosin and Special Stains in Helicobacter Pylori Detection and Analysis of Risk Factors Associated with Gastritis: A Study of 100 Cases. Masters thesis, Stanley Medical College, Chennai.
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Abstract
Helicobacter Pylori Was Now Accepted As A Major Cause Of Chronic Active Antral Gastritis And There Is Accumulating Evidence To Incriminate This Microbe In The Aetiology Of Duodenal Ulcer And Gastric Carcinoma. It Was Therefore Of Paramount Importance To Determine The Presence Of The Organism In Surgical Pathology Specimens In Order To Manage These Two Common Diseases Of The Upper Gastrointestinal Tract. Antral Biopsy Specimens Processed For Histology Would Therefore Provide An Easier And More Cost-Effective Alternative Means Of Diagnosing Helicobacter Pylori Infection. Various Special Stains Have Been Devised To Detect Helicobacter Pylori In These Histological Sections But Their Specificity And Sensitivity Vary Greatly. The Haematoxylin And Eosin Stain, Is The Most Frequently Used Stain In Histology. Modified Giemsa Stain Has Been Favoured Because Of Its Easiness To Perform And Availability In Most Histopathology Laboratories. However All The Above-Mentioned Stains Depend On The Morphology Of The Bacterium For Identification And It Is Possible That There Are Other Microbes In The Gastric Mucosa, Which Could Resemble And Become Difficult To Differentiate From Helicobacter Pylori. It Is Also Known That Helicobacter Pylori May Demonstrate Pleomorphism So That Depending On Morphology Alone May Not Be Reliable For Diagnosis. Immunohistochemical Techniques Have Been Developed And Use Of Anti Helicobacter Pylori Antibody Which Reacts With Somatic Antigens Of The Whole Bacteria Have Been Found To Correlate Well With The Presence Of The Bacteria. The Aim Of This Study Was Therefore To Ascertain The Reliability Of Modified Giemsa Stain In Comparison With Immunohistochemical Technique In Diagnosing Helicobacter Pylori. HELICOBACTER PYLORI Helicobacter Pylori -Spiral Campylobacter Like Bacteria Was Observed In Close Apposition To The Gastric Mucosa In Several Cases Of Gastritis And Peptic Ulcer, By Warren And Marshall In Australia In 1983.It Was Originally Named Campylobacter Pylori. When 16S Ribosomal RNA Gene Sequencing And Other Research Showed In 1989 That The Bacterium Did Not Belong In The Genus Campylobacter It Was Placed In Its Own Genus Helicobacter. The Genus Helicobacter Derived From The Greek Word Helix Means -"Spiral" Or "Coil" And Pylori Means- Gatekeeper.[1] Helicobacter Pylori's Helix Shape Is Thought To Have Evolved To Penetrate The Mucoid Lining Of The Stomach.[2] EPIDEMIOLOGY At Least Half The World's Population Are Infected By The Bacterium, Making It The Most Widespread Infection In The World.[3] Actual Infection Rates Vary From Nation To Nation; The Developing World Has Much Higher Infection Rates Than The West (Western Europe, North America, Australia), Where Rates Are Estimated To Be Around 25%.[3]. Infections Is Usually Acquired In Early Childhood In All Countries.[4]. However, The Infection Rate Of Children In Developing Nations Is Higher Than In Industrialized Nations, Probably Due To Poor Sanitary Conditions. In Developed Nations It Is Currently Uncommon To Find Infected Children, But The Percentage Of Infected Adults Increases With Age, With About 50% Of Patients Over The Age Of 60 Years And 10% Between 18 And 30 Years.[3].The Higher Prevalence Among The Elderly Reflects Higher Infection Rates During Their Childhood Rather Than Infection At Later Age.[4]. The Lower Rate Of Infection In The West Is Largely Attributed To Higher Hygiene Standards And Widespread Use Of Antibiotics. Despite High Rates Of Infection In Certain Areas Of The World, The Overall Frequency Of Helicobacter Pylori Infection Is Declining.[5].However, Antibiotic Resistance Is Appearing In Helicobacter Pylori And There Are Already Many Metronidazole- And Clarithromycin-Resistant Strains In Most Parts Of The World[6]. The Human Stomach Is The Primary Reservoir For The Organism And It Is Transmitted Via Oral-Oral Route And Possibly Via A Gastric – Oral And Fecal-Oral Route[7] GENERAL CHARACTERISTIC FEATURES Helicobacter Pylori Is A Helix Shaped, Gram Negative Bacterium, About 3 Micrometres Long With A Diameter Of About 0.5 Micrometres. It Is Microaerophilic ( It Requires Oxygen, But At Lower Concentration Than Is Found In The Atmosphere) . It Contains A Hydrogenase Which Can Be Used To Obtain Energy By Oxidizing Molecular Hydrogen (H2) That Is Produced By Intestinal Bacteria[8].It Produces Oxidase, Catalase, And Urease. It Is Capable Of Forming Biofilm[9] And Can Convert From Spiral To A Possibly Viable But Nonculturable Coccoid Form,[10] Both Likely To Favor Its Survival In Environment. The Coccoid Form Can Adhere To Gastric Epithelial Cells In Vitro.[11] PATHOGENESIS : Features Linked To Helicobacter Pylori Virulence: Flagella, Which Allow The Bacteria To Be Motile In Viscous Mucus Urease, Which Generates Ammonia From Endogenous Urea And Thereby Elevates Local Gastric Ph Adhesins; That Enhance Their Bacterial Adherence To Surface Foveolar Cells. Toxins; Such As Cytotoxin- Associated Gene (Caga), That Is Involved In Ulcer And Cancer Development OUTER MEMBRANE PROTEIN : Helicobacter Pylori Possess Five Major Outer Membrane Protein (OMP) Families. The Largest Family Includes Adhesins. The Other Four Families Include Porins, Iron Transporters, Flagellum -Associated Proteins And Proteins Of Unknown Function. Like Other Typical Gramnegative Bacteria, The Outer Membrane Of Helicobacter Pylori Consists Of Phospholipids And Lipopolysaccharides ( LPS). The O Antigen Of LPS May Be Fucosylated And Mimic Lewis Blood Group Antigens Found On The Gastric Epithelium.[12] The Outer Membrane Also Contains Cholesterol Glucosides, Which Are Found In Few Other Bacteria. Helicobacter Pylori Has 4-6 Lophotrichous Flagella. All Gastric And Enterohepatic Helicobacter Species Were Highly Motile Due To Flagella.[13] The Characteristic Sheathed Flagellar Filaments Of Helicobacter Are Composed Of Two Copolymerized Flagellins, Flaa And Flab. ADHESINS Outcome Of Helicobacter Pylori Infection Reflects Strain Specific, Environmental, And Host Related Factors. To Colonize The Stomach, Helicobacter Pylori Must Survive The Acidic Ph Of The Lumen And Burrow Into The Mucus To Reach Its Niche, Close To The Stomach's Epithelial Cell Layer. The Bacterium Has Flagella And Moves Through The Stomach Lumen And Drills Into The Mucoid Lining Of The Stomach[14]. To Avoid Being Carried Into The Lumen, Helicobacter Pylori Senses The Ph Gradient Within The Mucus Layer By Chemo Taxis And Swims Away From The Acidic Contents Of The Lumen Towards The More Neutral Ph Environment Of The Epithelial Cell Surface [15]. It Produces Adhesins Which Binds To Membrane-Associated Lipids And Carbohydrates And Help It Adhere To Epithelial Cells. For Example, The Adhesin Baba Which Binds To The Lewis Blood Group Carbohydrate Structures Are Present On The Ends Of MUC1 Carbohydrate Side Chain As Well As On Secreted Mucins. MUC1 Is Highly Polymorphic And Evidence Suggests That Functional Allelic Difference Affect Infection Susceptibility [16]. UREASE ENZYME : Helicobacter Pylori Produces Large Amounts Of The Enzyme Urease, Molecules Of Which Are Localized Inside And Outside Of The Bacterium. Urease Breaks Down Urea (Which Is Normally Secreted Into The Stomach) To Carbon Dioxide And Ammonia. The Ammonia Is Converted To Ammonium By Taking A Proton (H+) From Water, Which Leaves Only A Hydroxyl Ion. Hydroxyl Ions Then React With Carbon Dioxide, Producing Bicarbonate, Which Neutralizes Gastric Acid. The Survival Of Helicobacter Pylori In The Acidic Stomach Is Dependent On Urease. The Ammonia Is Toxic To Epithelial Cells. Other Products Of Helicobacter Pylori—Including Proteases, Vacuolating Cytotoxin A (Vac A), And Certain Phospholipase Damages The Epithelial Cells[17]. Following Attachment Of Helicobacter Pylori To Stomach Epithelial Cells, The Type IV Secretion System Expressed By The Cag "Injects" The Inflammation-Inducing Agent, Peptidoglycan, From Their Own Cell Wall Into The Epithelial Cells. The Injected Peptidoglycan Is Recognized By The Cytoplasmic Pattern Recognition Receptor (Immune Sensor) Nod1, Which Then Stimulates Expression Of Cytokines That Promote Inflammation[18].Outer Inflammatory Protein ( Oip A) And Cag Are Necessary For Full Activation Of The IL-8 Promoter. IL-8, A Potent Neutrophil Activating Chemokine Expressed By Gastric Epithelium Plays A Central Role In The Inflammatory Response [19]. SIGNS AND SYMPTOMS Most People (Over 80%) Infected With Helicobacter Pylori Show No Symptoms. Acute Infection May Appear As Acute Gastritis With Abdominal Pain (Stomach Ache) Or Nausea. Where This Develops Into Chronic Gastritis, The Symptoms, If Present, Are Often Those Of Non-Ulcer Dyspepsia: Abdominal Pain, Nausea, Bloating, Belching And Sometimes Vomiting. Individuals Infected With Helicobacter Pylori Have A 10 To 20% Lifetime Risk Of Developing Peptic Ulcers And A 1 To 2% Risk Of Acquiring Stomach Cancer [20]. Inflammation Of The Pyloric Antrum Is More Likely To Lead To Duodenal Ulcers, While Inflammation Of The Corpus (Body Of The Stomach) Is More Likely To Lead To Gastric Ulcers And Gastric Carcinoma[21]. MORPHOLOGY Gastric Biopsy Specimens Demonstrate Helicobacter Pylori In Infected Individuals. The Organism Is Concentrated Within The Superficial Mucus Overlying Epithelial Cells In The Surface And Neck Region. The Distribution Can Be Irregular, With Areas Of Heavy Colonisation Adjacent To Those With Few Organisms In Extreme Cases The Organisms Carpet The Luminal Surfaces Of Foveolar And Mucous Neck Cells, And Can Even Extend Into The Gastric Pits. Helicobacter Pylori Is Uncommon In Oxyntic Mucosa Of The Fundus And Body Except In Heavy Colonisation. Thus An Antral Biopsy Is Preferred For Evaluation Of Helicobacter Pylori Gastritis. Intraepithelial Neutrophils And Subepithelial Plasma Cells Are Characteristic Of Helicobacter Pylori [22].
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | Immunohistochemistry ; Hematoxylin ; Eosin ; Special Stains ; Helicobacter Pylori Detection ; Risk Factors ; Gastritis ; Cases Study. |
| Subjects: | MEDICAL > Pathology |
| Depositing User: | Subramani R |
| Date Deposited: | 27 Jun 2017 11:33 |
| Last Modified: | 22 Dec 2018 09:28 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/416 |
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