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HELICOBACTER PYLORI: UPDATE The role of Helicobacter Pylori (HP) in gastric The Medical Benefits Schedule The PyTest® has several ulcers has been wel established by Nobel changed in November 2006 advantages over other tests for Prize winners Professor Barry Marshal and to rebate diagnostic breath HP and is now available through Dr Robin Warren. Australian researchers Professor Barry Marshall conditions of overcrowding, hygiene and and Dr Robin Warren were awarded the Nobel questionable water supply. The bacteria may be Prize in medicine in 2005 for their groundbreaking spread to food via flies and cockroach excreta, achievement in 1981 of identifying the bacteria although spread by flies is less likely. Interestingly Helicobacter Pylori as the causative organism for there is a high prevalence of HP in sheep's milk and 70 to 90 per cent of gastric and duodenal ulcers. this may have been where homo-sapiens first Helicobacter Pylori (HP) is also found in 80 per acquired the infection. Surprisingly it does not cent of patients with gastric cancer and mucosal- survive in yoghurt.
associated lymphoid tumours, and has been classified as a carcinogen for these cancers. Ongoing Disease associations
research continues as to its relationship with cancer
and whether eradication therapy in the asymptomatic HP can adhere to the gastric epithelium via specific
patient may prevent gastric cancer.
adhesion molecules, then bacterial enzymes and cytotoxins can cause structural damage and induce HP is a gram-negative bacteria that has evolved an inflammatory response.
to inhabit the hostile environment of the human stomach. A spiral/helical shape and specialised Aspirin and other NSAID side effects are more motility al ow the organism to swim in a corkscrew- likely in the presence of HP infection. Al patients like fashion through the viscous gastric mucous with dyspepsia should be considered as possibly down to the gastric mucosa. It resists the effect of having the infection through its causal association gastric acidity by breaking down the endogenous with gastritis. There is an association with morning urea via the activity of the enzyme urease, creating a sickness in pregnancy and this is important to protective cloud of alkaline ammonia.
consider prenatal y.
First-line triple therapies include metronidazole, Epidemiology of Helicobacter Pylori
clarithromycin and a proton pump inhibitor. Other therapies exist for the 25 per cent of patients where Up to 40 per cent of Australians are colonised by first-line therapy fails to clear the infection (90 per HP. In some ethnic groups, over 50 per cent may be cent of patients with failed therapy have resitance colonised (eg some South East Asian groups). to metronidazole and clarithromycin). Recent work HP is most commonly spread by direct faecal oral in microbiology at Melbourne Pathology showed transmission, often within family groups. Toddlers amoxicillin and tetracyclines remain useful agents. often acquire HP from their mother due to shared The role of re-infection is still being determined.
eating habits. Acquisition later in life is often through Monitoring of patients to ensure bacterial eradication, hygiene factors. For example, HP is often found is associated with symptomatic improvement in under the fingernails and in the mouth, particulary in chronic inflammation. HELICOBACTER PYLORI: UPDATE cont.
body and is converted by the respiratory system to carbon dioxide (CO ).
THE UREA BREATH TEST FOR HELICOBACTER PYLORI Medications to avoid during the PyTest®.
The urea breath test was pioneered by Professor Barry Marshal in 1988. He has since fine-tuned the Mylanta, gaviscon test and PyTest® is now the only breath test accredited in Australia (TGA), USA (FDA) and Canada (Health Canada).
Features of the PyTest®
Flagyl, Amoxil, Klacid, Requires only a six-hour fast No baseline breath sample required Serological tests
Least invasive test for HP IgG and IgA serology is not useful for monitoring Col ection procedure takes less than 20 minutes eradication or acute infection. IgG tends to persist for Some medications must be avoided prior to test many years after infection and cannot be used as a measure of active disease. Serology may not detect all It is acceptable for patients to take medication for other strains of HP due to varying immune responses.
conditions and to have breakfast as the test can be performed in the afternoon after the fasting period. Other tests
Medicare-rebatable for both diagnostic testing and Faecal HP antigen testing offers some advantage in eradication purposes (one month after treatment is patients unable to withhold medications, or in young completed) from 1 November 2006.
children living in a household where someone has HP infection. Samples need to be fresh as levels can be low.
The PyTest® procedure
The PyTest® has a special y designed gelatine capsule
Gastroscopy and biopsy can show inflammation and containing maize starch microspheres impregnated by the bacteria using special stains. Two antral biopsies are 14C urea. The radioactivity involved is tiny; we are all general y recommended and the test has a 95 per cent exposed to twice that amount of radiation through our sensitivity and specificity.
normal environment each day.
The ‘rapid urease test' involves innoculation of gastroscopy samples into a medium where pH indicators change colour due to released ammonia. The test can 20mL of water. Three give a result within 20 minutes.
minutes is al owed then 20mL more In patients for whom repeated therapy has failed, highly water is swal owed sensitive culture on mucosal biopsy can be used. The culture takes seven days.
capsule is not lodged dr Zhong Lu MBBS, FRCPA, PhD in the oesophagus. Dr Zhong is a Chemical Pathologist at Melbourne After seven minutes, Pathology and also works at Austin Health. She the breath sample is graduated from the Guangzhou Medical Col ege in taken into a bal oon.
China then moved to Melbourne to study a Master of Human Nutrition at Deakin University. She The microspheres are released within two minutes of completed a PhD in Epidemiology and Preventive entering the stomach and can easily penetrate the Medicine at Monash University in 2001.
mucosal layer, al owing the test to operate reliably within 10 minutes. Tablets used in other tests take too For further information, please contact one of our Specialist Pathologists:dr Zhong Lu long to dissolve and urea solutions don't penetrate (pictured) MBBS, FRCPA, PhD - Chemical Pathologist dr Rob Baird the mucosal layer. Because urease is denatured at MBBS, FRACP (Infectious Diseases), FRCPA (Microbiology) Director of Microbiology pH<5, it is only found in the lower levels of the mucous Prof Prithi Bhathal MBBS, PhD, FRCPA - Histopathologist layer. Urea is then broken down to ammonia and dr Ken Sikaris MBBS, FRCPA, BSc(Hons), FAACB bicarbonate. The bicarbonate freely diffuses into the Director of Chemical Pathology Melbourne Pathology ABN 63 074 699 139 A subsidiary of SONIC HEALTHCARE LIMITED103 Victoria Parade Col ingwood, Victoria 3066 Switchboard 9287 7700 www.mps.com.au Details correct at time of printing - February 2007

Source: http://www.mps.com.au/media/75944/helicobacter%20march%2007.pdf