ACP. Best practice no 154. February 1999. Helicobacter pylori

Helicobacter pylori genotyping and sequencing using paraffin-embedded biopsies from residents of colombian areas with contrasting gastric cancer risks

BACKGROUND

cagA-positive and vacA s1 and m1 genotypes of Helicobacter pylori are associated with an elevated risk of gastric cancer (GC). We determined these genotypes using paraffin-embedded gastric biopsy specimens harvested from infected individuals and compared genotype distributions in two Colombian populations residing in geographic regions with a high and low incidence of GC.

METHODS

DNA from paraffin-embedded gastric biopsies from 107 adults was amplified using primers specific for cagA, for the cag'empty site', for the s and m alleles of vacA, and for H. pylori 16S rRNA.

RESULTS

H. pylori infection was detected by molecular assays in 97 (90.7%) biopsies. Complete genotyping of cagA and vacA was achieved in 94 (96.9%) cases. The presence of cagA was detected in 78 of 97 cases (80.4%); when considered separately, cagA and vacA s regions were not significantly associated with a particular geographic area. The vacA m1 allele and s1m1 genotypes were more common in the area of high risk for GC (p = .037 and p = .044, respectively), while the vacA m2 allele and s2m2 genotypes were more prevalent in the low-risk area. The prevalence of the combination of cagA-positive, vacA s1m1 genotypes was 84.3% and 60.5% for high and low risk areas, respectively (p = .011).

CONCLUSIONS

H. pylori cagA and vacA genotyping from paraffin-embedded gastric biopsies permitted reliable typability and discrimination. The more virulent cagA-positive s1m1 strains, as well as vacA m1 genotype, were more prevalent in high risk than in low risk areas, which may contribute to the difference in GC risk between those two regions.

Patients' attitudes to Helicobacter pylori breath and stool antigen tests compared to blood serology

BACKGROUND

The National Institute for Health and Clinical Excellence (NICE) recommends that patients with uninvestigated dyspepsia, unresponsive to proton pump inhibitors, should be tested for Helicobacter pylori using a stool antigen or urea breath test rather than blood-based serology.

OBJECTIVE

To determine if a stool antigen or urea breath test is acceptable to patients.

METHOD

Satisfaction questionnaire circulated to all primary care patients who had blood serology for H. pylori between January and July 2004.

RESULTS

Four hundred and sixty-two out of 717 Gloucestershire patients returned the questionnaire. Three-quarters of respondents stated that they would be willing to provide a stool or breath H. pylori test if they were told they were more accurate than the blood test. If the blood test was not available, 58% stated they would prefer the breath test and 34% the stool test. When patients were not given an explanation for the transfer to the new tests, only 11% stated they would prefer to provide a stool and 19% the breath test. 80% required an extra appointment for their blood test.

CONCLUSION

The majority of patients would be happy to provide a stool sample or breath test provided they are made aware that these tests are more accurate than blood serology.

Helicobacter pylori in colorectal neoplasms: is there an aetiological relationship?

BACKGROUND

This pilot study was carried out to determine whether Helicobacter pylori can be detected in normal colon or in association with colorectal neoplasia.

METHODS

Paraffin processed colonic tissue blocks of normal colonic mucosa (n = 60), and patients diagnosed as adenoma (n = 60), and adenocarcinoma (n = 60) were retrieved from our archive; the adenoma group included tubular (n = 20), tubulovillous (n = 20) and villous adenomas (n = 20). 4 mum sections were stained by immunohistochemical methods using anti-Helicobacter pylori antibodies (polyclonal NCL-HPp and monoclonal NCL-C-jejuni).

RESULTS

Significant numbers of Helicobacter pylori were identified in tubular adenomas (OR = 11.13; 95%CI = 1.62-76.70), tubulovillous adenomas (OR = 10.45; 95%CI = 1.52-71.52) and adenocarcinomas (OR = 8.13; 95%CI = 1.40-46.99) compared to controls: there was no association in numbers of Helicobacter pylori and villous adenomas (OR = 2.95; 95%CI = 0.29-9.96).

CONCLUSION

We conclude that although, in this pilot study, there appears to be an association in the prevalence of Helicobacter pylori with some, but not all, colorectal neoplasms, we can not infer causality from these results. These findings need to be further substantiated with a prospective study and the use of molecular biological techniques to determine a causal association.

Variation in the use of H. pylori tests in UK general practice--a qualitative study

BACKGROUND

Although serology is the main Helicobacter pylori test used by general practitioners in the UK, there is no information available on variation in requesting rates.

AIM

To explore the reasons for any variation in H. pylori serology testing by general practices in the UK using qualitative methods.

METHODS

Serology requesting rates were determined using laboratory and population data. Staff from randomly selected practices in the lowest and highest quintiles of testing attended focus groups to discuss the management of H. pylori and dyspepsia. Transcribed data were analysed using an interpretative phenomenological approach.

RESULTS

Serology submission varied 600-fold (0.1-59/1000 population/year) and H. pylori positivity rate 17-100%. Low-testing practices were less aware of the benefits of H. pylori testing and had shorter endoscopy waiting times. They preferred endoscopy diagnosis over serology test. Three high-testing practices had a high non-white population with high H. pylori positivity. Most staff knew little about the predictive value of serology, the availability of urea breath test on prescription or the existence of a stool test.

CONCLUSIONS

Seroprevalence of H. pylori is still high in dyspeptics, especially in non-white populations. Laboratories and primary care trusts should audit H. pylori requests and endoscopy referrals, target education at high endoscopy referrers and low H. pylori testers and inform clinicians of the more accurate H. pylori tests and NICE dyspepsia guidance.

Characterisation of Helicobacter pylori isolates from the north-eastern region of Mexico

The vacA and cagA genotypes of 50 Helicobacter pylori isolates from patients in the north-eastern region of Mexico were characterised by PCR, and the correlation between genotypes and different clinical outcomes was investigated. Strains of H. pylori that are vacA s1/m1 and cagA positive have previously been associated with more severe clinical outcomes, and some studies have shown differences in the vacA and cagA genotypes in different geographical regions. The six possible combinations of the vacA signal (s) and middle (m) regions were identified in this population, and the most frequent genotype was s2/m2. Thirty-two (64%) isolates were identified as cagA-positive. The s region was not amplified from seven of the cagA-positive isolates, and the m region was not amplified from one cagA-negative isolate, indicating that additional subfamilies of s and m genotypes may exist. The s1/m1 genotype was associated with cagA-positive strains (p < 0.05). No association was found between the vacA and cagA genotypes and clinical outcomes.

Cellular turnover of normal gastrointestinal epithelium assessed by changes in telomeric: total DNA signal ratios

OBJECTIVES

The reasons why different areas of gastrointestinal mucosa exhibit widely different rates of malignant change are still poorly understood. Malignancy rates rise markedly with age. We therefore hypothesised that rates of malignant change might correlate with rates of ageing as judged by stem cell turnover. Telomeric DNA is lost with each cell division and so acts as a measure of the number of cell divisions undergone by stem cells. We measured telomeric:total DNA signal ratios in normal gastric (Helicobacter pylori-positive and H. pylori-negative), duodenal and colonic mucosa to see whether ratios correlated with propensity to malignancy.

PATIENTS

Subjects undergoing diagnostic upper (n = 93) or lower (n = 45) gastrointestinal endoscopy, whose mucosa appeared macroscopically normal, sampled over a wide age range.

METHODS

DNA was extracted from paired blood and mucosal samples (colonic or gastric and duodenal). Telomere length was assessed by dot blot hybridisation with an oligonucleotide-containing telomeric sequence compared with the signal obtained from total genomic DNA. Helicobacter status was assessed by Campylobacter-like organism (CLO) test and serologically.

RESULTS

Telomeric signal ratios were scattered, but correlated within individuals. The ratios tended to decrease with age but the rates of decrease did not correlate with rates of malignant change. Gastric tissue had the shortest ratios and duodenal ratios decreased fastest.

CONCLUSIONS

The telomeric signal ratios did not suggest any obvious basis for differential rates of disease especially malignancy. Infection with H. pylori was not associated with lower gastric telomere ratios.

Helicobacter pylori: a microbiologist's view

Helicobacter pylori infection is known to cause a number of gastrointestinal diseases. From the standpoint of a microbiologist there are several important facets to this organism, which include the nature of the organism, it's diagnosis and the effectiveness of eradication therapy.

Comparison of Helicobacter pylori prevalence in symptomatic patients in northeastern Mexico with the rest of the country: its association with gastrointestinal disease

BACKGROUND

Prevalence of Helicobacter pylori varies among different geographic regions. The aim of this study was to assess H. pylori prevalence in symptomatic patients in northeastern Mexico and its possible association of H. pylori with disease.

METHODS

We studied 261 symptomatic patients (female/male 1.44, mean age 53 years) who underwent gastrointestinal endoscopy at Hospital Universitario Dr. José Eleuterio González in Monterrey, Nuevo León, Mexico. Among patients included in this study, 209 (80.1%) had nonulcer dyspepsia (NUD), 30 (11.5%) peptic ulcer disease (PUD), and 22 (8.4%) high-grade dysplasia or gastric cancer. H. pylori status was determined by histology, positive rapid urease test, culture, or IgG whole-cell anti-H. pylori. Specific IgG antibodies for CagA status were determined by ELISA as previously described. Patients were defined as infected with H. pylori by positive results of two or more diagnostic tests used.

RESULTS

Overall prevalence of H. pylori was 67.8%. According to clinical presentation, gender (male) was related with gastric cancer (p <0.01) and with PUD (p <0.05). Of 177 patients infected with H. pylori, 90 (50.8%) were seropositive for CagA antigen; in addition, H. pylori CagA+ was more common in patients with PUD (77.8%) than with NUD (43.2%) (p <0.05). However, no association was found between gastric cancer patients and presence of CagA+ H. pylori strains.

CONCLUSIONS

H. pylori prevalence in symptomatic patients in northeastern Mexico is as high as the prevalence reported for the entire country. We confirmed that patients with gastric cancer and PUD are more likely to be male. CagA+ strains were associated with patients who presented PUD but not gastric cancer.

A pilot study to determine the effectiveness of garlic oil capsules in the treatment of dyspeptic patients with Helicobacter pylori

BACKGROUND

Resistance of Helicobacter pylori to clarithromycin and metronidazole is now found worldwide. Steam-distilled garlic oil has in vitro activity against H. pylori and may be a useful alternative treatment strategy.

MATERIALS AND METHODS

In this pilot study dyspeptic patients with positive serology for H. pylori confirmed by 13C urea breath test (UBT), at 0 and 2 weeks, were enrolled. Treatment consisted of one 4 mg garlic oil capsule with a meal four times per day for 14 days. H. pylori eradication was defined as a negative UBT at both follow-up appointments. Suppression was defined as a 50% fall in 13C excess between baseline and follow-up 1.

RESULTS

Five patients completed the study. There was no evidence of either eradication or suppression of H. pylori or symptom improvement whilst taking garlic oil.

CONCLUSION

These negative results show that, within the gastric milieu, garlic oil at this dose does not inhibit H. pylori. A higher dose administered for a longer time-period may be effective. Antibiotics are usually combined with a proton-pump inhibitor or bismuth salt, as the only antibiotic with any in vivo activity against H. pylori in monotherapy is clarithromycin. A proton pump inhibitor raises gastric pH and, by increasing bacterial division, may increase the in vivo activity of garlic oil. This may be worth pursuing in a future trial.