Helicobacter Pylori (PDF)

INTRODUCTION Helicobacteria is a genus of Gram-negative bacteria. It has a helix shape. It involves more than 35 species. The species of medical importance is known as H. pyloric which is found in the upper lining of the gastrointestinal tract as well as liver of mammals and some birds....

INTRODUCTION Helicobacteria is a genus of Gram-negative bacteria. It has a helix shape. It involves more than 35 species. The species of medical importance is known as H. pyloric which is found in the upper lining of the gastrointestinal tract as well as liver of mammals and some birds. 1 Cont...................... The are many species of helicobacter but the specie of medical importance is Helicobacter pylori previously known as Campylobacter pylori. It the main cause of gastritis and gastric ulcers. Others are H.cinnaedi and H.fenneliae,H.mustelae,H.felis 2 Epidemiology of h.pylori H.pylori is present on the gastric mucosa of less than 20% of persons under age 30,but increases in prevalence to 40-60% of persons age 60,including persons who are asymptomatic In developing countries the prevalence of infections may be 80% or higher in adult. Person to person transmission of H pylori is likely in causing intrafamilial clustering of infections occurs. Acute epidemics of gastritis suggest a common source for H pylori. 3 H. pylori 4 H.Pylori structure 5 general characteristic of H.pylori Gram-negative,3 micrometres long,0.5 micrometres diameter Present in patient with chronic gastritis and gastric ulcers Helix-shaped, curved rod, not spirochaete Microaerophilic(low oxygen conc.than that of atm) Can appear as coccoid shape after prolonged in vitro culture, non cultural state. Has 2 to 6 unipolar,sheathed flagella but lacks fimbrial adhesins 6 Cont................... It found mostly in mucus in the inner surface of epithelium lining the stomach This help to avoid low pH of the stomach but also capable of neutralize acid in its environment by producing urease which break urea present in the stomach to CO2 and ammonia 7 Cont................... It is capable of forming and convert from spiral to a possibly viable but nonculturable coccoid form both likely to favour its survival. 8 VIRULENCE AND ANTIGENIC FACTORS It contains a hydrogenase,hence obtain energy by oxidizing molecular hydrogen It produces oxidase,catalase and urease Capable of forming biofilms and can convert from spiral to a possibly viable but nonculturable coccoid It has five major outer membrane protein(OMP) families, putative adhesins,porins,iron transporter, flagellum-associated protein and protein of unknown function 9 Cont………….. The main bacterial virulence factor comprise adhesins (BabA,SabA) Vacuolating cytotoxin VacA The patterns of cytokine production in response to the infection is one of main host determinant involved in limiting the infection outcome to gastritis or in favoring peptic ulcer or cancer on set Bacterial virulence factors and cytokine gene polymorphisms as determinants of infection outcome 10 Transmission H pylori is ubiquitous and acquired by ingestion. Prevalence of infection is relatively low during childhood but rises to 40% 50% in older adults. 11 Pathogenesis of h. pylori After ingestion of H pylori, grows optimally at Ph of 6.0-7.0 and go to deep in the mucus layer near the epithelial surface and do the following: Neutralization of local stomach by urease produced ammonia (NH₃) promotes initial colonization. Rapid penetration of gastric mucus facilitated by multiple flagella. Localised tissue damage by mucinase and cytotoxin stimulates infiltration of inflammatory cells Increased secretion of gastrin and gastric acid stimulated by infection promotes gastric metaplasia 12 Diseases due to H pylori. Stomach and duodenal ulcers Chronic type B gastritis (superficial and atrophic) with possible progression to gastric adenonocarcinoma 13 Clinical findings Acute infections can yield an upper gastro intestinal illness with nausea and pain; vomiting and fever may be present also. The acute symptoms may last for less than one week up to two weeks. Once colonized the H pylori infection persist for years H pylori also may have a role in gastric carcinoma and lymphoma. 14 Diagnostic laboratory test SPECIMENS Gastric biopsy can be used for histological examinations and used for culture. Blood is collected for determination of serum antibodies. SMEARS The diagnosis of gastritis and H pylori infection can be made histologically. A gastroscopy procedure with biopsy is required. 15 DIAGNOSTIC CONT…. CULTURE H pylori grows in 3-6 days when incubated at 370C in microaerophillic environment. The media for primary isolation include Skirrow’s medium..ANTIBODIES The serum antibody persists even if the H pylori infection is eradicated and the role of antibody tests in diagnosing active infection or following therapy is therefore limited. 16 Diagnostic conti….SPECIAL TEST Alternatively, 13C or 14C labeled urea can be used. If H. pylori is present, CO2 is detected in the breath. 17 Immunity Patients infected with H pylori develop an IgM antibody response to the infection. Subsequently, IgG and IgA are produced, and these persist, both systemically and at the mucosa, in high titer in chronically infected persons. Early antimicrobial treatment of H pylori infection blunts the antibody response; such patients are thought to be subject to repeat infection 18 symptoms An ache or burning pain in your abdomen. Nausea Vomiting Frequent burping Bloating Weight loss Difficulty in swallowing Bloody or black tarry stools Vomit that look like coffee 19 Treatment Triple therapy continued for 2 weeks is commonly used Bismuth salt + with metronidazole +amoxicillin or tetracycline Bismuth salt + ranitidine + clarithyromycin Proton pump inhibitor eg omeprazole,+amoxicillin + clarithromycin 20  List 5 ways of preventing H. pylori 21 references http://digestive.niddk.nih.gov/ddiseases/hpylori. http://www.uptodate.com 22