1. Helicobacter pylori

2. Background 1983-discovered by Warren and Marshall in Australia Discovery revolutionised the treatment of duodenal and gastric ulcers Earned them the Nobel Prize for Medicine in 2005 Formerly known as Campylobacter pyloridis

3. Nearly 20 species of Helicobacter are now recognised The gastric helicobacters colonise the stomachs of animals. The monkey, cat, dog, cheetah all harbour their own species H. cinaedi and H. fennelliae are associated with proctitis in homosexual men H. pylori are found in the human stomach. Molecular studies suggest transmission from an animal source.

4. Helicobacter pylori McColl K. N Engl J Med 2010;362:1597-1604

5. Description Gram-negative spiral bacillus Fastidious in terms of growth requirements :strictly micro-aerophilic :require C02 for growth :on charcoal medium Has a tuft of sheathed unipolar flagella; specially adapted to colonise mucous membranes

6. Gram stain of H. pylori recovered from an individual without prior antimicrobial therapy. Organisms display typical ‘seagull’-like appearance.

7. Hallmark of the species is production of urease enzyme -urease breaks urea down to C02+NH3 -amonia is a strong base -process helps H. pylori survive strongly acidic stomach conditions Very fragile (a point of importance when referring samples to the lab)

8. Epidemiology H. pylori infection occurs worldwide Prevalence varies greatly among countries and population groups 20 – 50% prevalence in middle age adults in industrialised countries >80% prevalence in middle age adults in developing countries :may reflect poorer living conditions

9. Transmission Oral ingestion of bacterium within families (esp children) person-person contact faecal-oral transmission ?role of water borne transmission Usually contracted in the first 2 years of life

10. Site of infection Highly adapted organism that lives only on gastric mucosa Gastric antrum is the most favoured site Present in the mucus that overlies the mucosa

11. Gastric-biopsy specimen showing Helicobacter pylori adhering to gastric epithelium and underlying inflammation McColl K. N Engl J Med 2010;362:1597-1604

12. Course of infection After several days incubation period, patients suffer mild attack of acute gastritis -abdominal pain -nausea -flatulence -bad breath Symptoms last about 2/52 but hypochlorhydria can last up to one year

13. Despite a substantial antibiotic response, infection and chronic gastritis persist After decades there may be progression to atrophic gastritis (conditions which are inhospitable for the bacteria) and numbers reduce

15. The outcome of infection by H. pylori reflects an interaction between: Strain virulence Host genotype Environmental factors

17. H. pylori infection directly associated with PUD -lifetime risk 3% in US, 25% Japan -eradication provides long-term cure Gastric carcinoma -strong evidence of increased risk 0.1-3% -unclear whether eradication reduces the risk of gastric cancer MALT lymphoma -72%→ 98% of MALT lymphoma infected with H. pylori

18. Laboratory diagnosis: non-invasive tests Serology : detect an immune response by examining a blood sample for abs to the organism (ELISA) : poor accuracy Urea breath test : a urea solution labelled with C14 isotope is given to pt. The C02 subsequently exhaled by the pt contains the C14 isotope and this is measured. A high reading indicates presence of H. pylori

19. Faecal antigen test : detect H. pylori antigens in faecal specimens Polymerase chain reaction (PCR) : can detect HP within a few hours. Not routine in clinical use.

20. Invasive testing 1.Histological examination of biopsy specimens of gastric/duodenal mucosa take at endoscopy 2.CLO-test ® : based again on urease-production by the organism->NH3 production->rise in pH=>change in the colour indicator of the kit -High sensitivity and specificity -Prompt result

21. Invasive testing 3.Culture : -no more sensitive than skilled microscopy of histological sections -used for antibiotic resistance testing -requires selective agars and incubation periods

22. Tests for Helicobacter pylori Infection McColl K. N Engl J Med 2010;362:1597-1604

23. Indications for therapy Strongly recommended Duodenal or gastric ulcer MALT lymphoma Atrophic gastritis Recent resection of gastric cancer Maastricht 2-2000 Consensus Report

24. Indications for therapy Treatment advised Functional dyspepsia Gastro-oesophageal reflux disease (patients requiring long-term acid suppressive therapy) Use of NSAIDs Maastricht 2-2000 Consensus Report

25. Treatment Goal of treatment to eradicate infection Triple therapy regimens consist of one anti- secretory agent and two antimicrobial agents for 7 to 14 days Triple therapy regimens must - have cure rate of approximately 80% - be without major side effects - minimal induction of resistance

26. First line treatment Combination of two or more antimicrobial agents increases rates of cure and reduces the risk of selecting for resistant H. pylori Many factors may result in failure of treatment microbial factors patient compliance geographical differences

27. First line therapy PPI b.d. + clarithromycin 500mg b.d. + amoxicillin 1000mg b.d. or metronidazole 400mg BD minimum of 7 days In case of failure Second line therapy PPI b.d. + bismuth subsalicylate/subcitrate 120mg QDS + metronidazole 500mg t.d.s. + tetracycline 500mg q.d.s. for a minimum of 7 days If bismuth is not available, PPI based triple therapies should be used Subsequent failures should be handled on a case-case basis. Patients failing second-line therapy in primary care should be referred Maastricht 2-2000 Consensus Report

28. NEJM 2002;347:1175-86

29. Guidelines for Evaluation and Management of Helicobacter pylori Infection McColl K. N Engl J Med 2010;362:1597-1604

30. Reinfection Reinfection following successful bacterial cure is unusual Commonly represents recrudescence of the original bacterial strain In adults, reacquisition of the bacteria occurs in <2%/persons/year which is similar to the rate of primary infection in adults

31. Failure of treatment Failure of initial course occurs in 1 in 5 2 nd -line Tx : either an alternative regimen quadruple Tx (PPI+bismuth+2 antibx)

32. Key points ->H. pylori is a flagellated spiral micro-aerobe ->Infection is a risk factor for gastric cancer ->Causes PUD and gastritis ->Produces a cell-damaging toxin ->Transmission route is unclear ->Dz rates are falling in industrialised countries ->Tx is by eradication using combination therapy

33. Recommendations The noninvasive test-and-treat strategy for H. pylori infection is reasonable for younger patients who have upper gastrointestinal symptoms but not alarm symptoms Noninvasive testing can be performed with the use of the urea breath test, fecal antigen test, or serologic test; the serologic test is the least accurate Triple therapy with a proton-pump inhibitor, clarithromycin, and amoxicillin or metronidazole remains an appropriate first-line therapy Recurrence or persistence of symptoms after eradication therapy for uninvestigated dyspepsia is much less likely to indicate that treatment has failed than to indicate that the symptoms are unrelated to H. pylori infection.

34. Recommendations Further eradication therapy should not be considered unless persistent H. pylori infection is confirmed Data are lacking to inform the optimal management of recurrent or persistent dyspepsia after noninvasive testing and treatment of H. pylori infection Options include symptomatic acid-inhibitory therapy, endoscopy to check for underlying ulcer or another cause of symptoms, and repeat of the H. pylori test-and-treat strategy; other potential reasons for the symptoms should also be reconsidered

35. Clinical Practice Helicobacter pylori Infection

36. Amoxicillin resistance Amoxicillin resistance rare (0.3%-1.4% generally, rates as high as 38% have been reported) Stable resistance has been reported Because H. pylori can exchange DNA through natural transformation and also through conjugation, spread of amoxicillin resistance among H. pylori is potentially a major threat ?Restriction of indications for treatment rather than indiscriminate eradication of H. pylori

37. Risk factors for resistance Risk factors for metronidazole resistance Sex – female > male Ethnicity – Asian > European Test method – use of E test vs. agar dilution Risk factors for clarithromycin resistance Geographical region – prescribing trends/genotype Age – increasing age Sex – female >male Ulcer status – inactive >active

38. Consumption & Resistance Perez Aldana et al. – 593 Japanese patients dyspepsia, no previous triple therapy Clarithromycin resistance 7% in 1997/8 to 15% in 1999/2000 Metronidazole resistance 6.6% in 1997/8 to 12% in 1999/2000 (Amoxicillin resistance reported 0.3%) Postulated that increase in antibiotic resistance was associated with a huge increase in clarithromycin use in Japan between 1993 and 2000 Consumption of metronidazole gradually increased during that time Rate of resistance to metronidazole low, compared to worldwide rates, due to low consumption of metronidazole in Japan

39. Secondary resistance Development of secondary resistance for clarithromycin and/or metronidazole may occur in 50% of cases AMNCH study (1997): secondary resistance to clarithromycin acquired in 58.3% of strains in cases of treatment failure Using most effective regimen will help to minimise developed of secondary resistance

40. Resistance – primary & secondary AMNCH (1997) Clarithromycin, metronidazole, omeprazole x 1/52 Primary resistance – MET 35.6%, CLA 3.4% Eradication rate 81.6% overall: 98.2% fully sensitive isolates; 57.1% metronidazole resistant strains; 0% dual resistant strains Secondary resistance to clarithromycin acquired in 58.3% of cases of treatment failure

41. Antibiotic sensitivity testing Excellent eradication rates have been achieved when prior resistance to one particular antibiotic was known Methodological problems :- slow growing microaerophilic organism (10 – 14 days) and difficulty interpreting susceptibility data More than 50% of the population may carry a mixture of sensitive and resistant strains in non- uniform distribution May achieve better results if multiple biopsies from several sites are used

42. Molecular testing Clarithromycin Molecular assays detecting 23S rRNA mutation esp. PCR-RFLP Can be performed on DNA from gastric aspirate or biopsy - ?same day results Others e.g. DNA enzyme immunoassay (DEIA), PCR line probe assay (LiPA) LiPA detects seven distinct resistance mutations – suitable for testing large numbers of people LiPA assay – H. pylori in West of Ireland – clarithromycin resistance 27% (not correlated with conventional C&S)

43. First line therapy PPI (RBC) b.d. + clarithromycin 500mg b.d. + amoxicillin 1000mg b.d. or metrodiazole 500md BD minimum of 7 days In case of failure Second line therapy PPI b.d. + bismuth subsalicylate/subcitrate 120mg QDS + metronidazole 500mg t.d.s. + tetracycline 500mg q.d.s. for a minimum of 7 days If bismuth is not available, PPI based triple therapies should be used Subsequent failures should be handled on a case-case basis. Patients failing second-line therapy in primary care should be referred Maastricht 2-2000 Consensus Report

44. 2 nd line treatment Quadruple therapies with bismuth, PPI + 2 antibiotics Success rate of eradication variable - <60-100% Eradication rates dependent on 1 st line therapy used and primary resistance rates 78-80% eradication achieved in an area where metronidazole resistance is 40% AMNCH study(1997): only 57.1% eradication rate with metronidazole resistance and 0% (0/3) for dual resistance

45. Other 2 nd line options “Rescue” therapies with rifabutin - promising with rates of 78.6% despite multiple therapies (resistance H. pylori rpoB gene) Stepwise therapies combining triple therapy, quadruple therapy, high doses of clarithromycin and proton pump inhibitor in a stepwise fashion (100% eradication in one series)

46. Gram stain of H. pylori recovered from patient, C.B. following 3 courses of antimicrobial therapy. Organisms appear enlarged and of abnormal morphology.

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48. Host response to infection H. pylori attaches to gastric epithelial cells triggering host inflammatory response HP infected patients gastric epithelium have enhanced levels of IL-1β, IL-2, IL-6, IL-8, TNFα. IL-8 appears to have central role, acting as a potent neutrophil activating chemokine

49. Host response to infection H. pylori attaches to gastric epithelial cells triggering host inflammatory response H. pylori bind to class II MHC molecules on surface of gastric epithelial cells inducing apoptosis HP urease & porins may contribute to extravasation & chemotaxis of neutrophils HP infected patients gastric epithelium have enhanced levels of IL-1β, IL-2, IL-6, IL-8, TNFα IL-8 appears to have a central role

50. Host response to infection Marked systemic & mucosal humoral response – antibodies do not lead to eradication of the infection but may contribute to tissue damage Th1 response predominates and Th1 cytokines promote gastritis – may occur due to increased IL-8 production [Th2 response expected (extracellular pathogen) does not occur, would protect gastric mucosa]

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52. Host response Most disease causing HP strains are type I containing the cag-pathogenicity island (PAI) cag-PAI carrying strains induce a much stronger IL-8 response than cag-negative Proteins encoded by cag-PAI -induction of IL-8 production of gastric epithelial cells -translocation of CagA protein from bacteria to host

53. Pathogenesis HP genome studies have shown that the genome changes continuously during chronic colonisation importing small pieces of foreign DNA from other HP strains Phase variable genes encode proteins including enzymes modifiying surface antigens, control the entry of foreign DNA into the bacteria and influence motility

54. Pathogenesis Urease production essential for survival – urease hydolyses urea into carbon dioxide & ammonia permitting survival in acidic milieu Motility essential for colonisation – HP flagella have adapted to gastric niche. Vacuolating cytotoxin (VacA) – expressed by majority of strains of HP, appears to increase bacterial fitness Huge variation in VacA strains

55. Diagnosis Minimally invasive testing Urea breath test (UBT) - initial diagnosis & follow up for eradication [sensitivity/specificity 90%] Serological testing – pre-treatment diagnosis of HP infection. AMNCH study (2000): 82.4% sensitive and 85% specific Stool antigen test – 89-98% sensitivity & >90% specificity Stool immunoassay & PCR – under investigation

56. Diagnosis Endoscopy & biopsy indicated:- Severe symptoms Anaemia Weight loss Patients >50 years

57. Diagnosis Urease test (CLO) on biopsy specimen – rapid detection (sensitivity 79 – 100%, specificity 92 – 100%) Sensitivity of urease test can be improved by additional biopsies False negatives – active or recent bleeding, antibiotic or antisecretory therapy Histological examination – can be performed if urease test negative (>90% sensitive and specific)

58. Treatment failure Treatment failure may result from:- Bacterial resistance – in theory the most important factor in failure of primary treatment Poor adherence to antibiotic guidelines Patient compliance – positive role shown for compliance enhancing programmes Geographical region – bacterial/patient genotype, prevelance of resistance, local antibiotic use Cost & duration of therapy Minors:- drug metabolism pathways (e.g. CYP2C19 genotype), intragastric pH, antimicrobial stability