Clinical significance of Helicobacter pylori seropositivity and seronegativity in asymptomatic blood donors

To determine the clinical significance of Helicobacter pylori seropositivity and seronegativity in healthy blood donors, we carried out a serological evaluation of Helicobacter pylori status and endoscopy in a healthy blood donors population. In all, 1010 donors were screened for Helicobacter pylori by IgG ELISA and assessed for pepsinogen I and gastrin levels by RIA; 298 IgG seropositive and 61 seronegative subjects underwent endoscopy with biopsies. Of 359, 165 were also tested for CagA by western blotting. Of the 298 IgG seropositives, 274 were shown to be infected on biopsy testing. Endoscopy revealed 70 peptic ulcers, 41 cases of erosive duodenitis, and two gastric cancers. In all 105 seropositive donors were tested for CagA and 69 were CagA positive [34/58 gastritis (58.6%), 24/35 duodenal ulcer (68.6%) and 11/12 gastric ulcer (91.6%)]. Histologically active/chronic gastritis was associated with CagA: 88.4% vs 50% (CagA seropositive vs seronegative). Of the 61 IgG seronegatives, 59 were negative on biopsy testing. At endoscopy three had duodenitis. Of the 60/61 IgG seronegatives tested for CagA, one had a moderate reaction. Duodenal ulcer donors showed higher pepsinogen I levels than donors without duodenal ulcers (97.7 microg/ml vs 80.9 microg/ml respectively). Screening for Helicobacter pylori and anti-CagA seropositivity and pepsinogen I can identify individuals likely to have gastroduodenal pathology even in the absence of symptoms.

Routes of transmission of Helicobacter pylori infection

Helicobacter pylori is an important gastroduodenal pathogen, which has been recognized as a Class I carcinogen factor for gastric cancer and gastric mucosa associated lymphoid tissue lymphomas. In spite of the world-wide spread of the infection, the route of transmission is still not known. We reviewed data from several sero-epidemiological studies and aimed to identify potential sources of Helicobacter pylori infection. Available evidence strongly suggests an inverse correlation between socio-economic status and prevalence of Helicobacter pylori. The infection is acquired mostly during childhood in the third world, but is rare in children in developed countries, where the prevalence of Helicobacter pylori increases with age. Following the detection of the bacterium in saliva, faeces, and gastric juice, oral-oral or faecal-oral transmission and iatrogenic spread, through the use of unsterile endoscopes, have been proposed as possible routes of infection. Helicobacter pylori has also been found in some domestic cats, but at present, the risk of infection from these animals appears slight. The mode of transmission of Helicobacter pylori, as is yet, not known. Available information support the hypothesis of spread through close personal contact, considering humans as the only significant reservoir of infection.

["Hepatitis" A virus g: myth or reality? VHG/GBH-C: diagnosis, epidemiology, transfusion risk, and pathogenicity]

The recently discovered G virus (also called either GBV-C or HGV) is transmitted by blood transfusion as well as by sexual intercourse. The global prevalence of GBV-C is high, not only in those groups classically known to be exposed to parenteral risks (i.v. drug users, polytransfused patients), but also in the blood donors population. The diagnosis of active infection lies on the search of GBV-C RNA by Polymerase Chain Reaction whereas that of resolved (past) infection lies on the presence of specific antibodies. Till now, it has not been possible to correlate convincingly the presence of GBV-C RNA with any acute or chronic hepatopathy. On the contrary, a lot of arguments tend to suggest that the GBV-C is not pathogenic for the liver, although some modes of transmission are common with those of other (known and probably not known) hepatotropic viruses. According to the actual knowledge of the consequences of GBV-C infection, it appears as non relevant to instaure a systematic screening of this new virus in blood donors.

The European meeting on Helicobacter pylori: therapeutic news from Lisbon

The current standard of Helicobacter pylori treatment has been confirmed by the studies presented at the Lisbon workshop--that is, one of three one week proton pump inhibitor (PPI) based triple therapies comprising a twice daily standard dose of a PPI in combination with two of the following antimicrobial agents: clarithromycin, amoxycillin, or a nitromidazole. This standard of treatment is also highly efficacious and cost-effective in routine community practice. The current data confirm the equivalence of ranitidine bismuth citrate to PPI, and of azithromycin to clarithromycin. The optimum dose for azithromycin has not yet been defined. There is some evidence that in certain regions treatment for more than one week may be advantageous. The reasons are still not clear. However, microbial resistance may be one important factor, as it has a substantial effect on treatment outcome and the prevalence of resistance varies considerably in different areas. The negative impact of resistance is increased by shortening the treatment time. At present, there is no general necessity to test for resistance before treatment. However, before selection of a second line treatment, testing for resistance is recommended.

Blood tests in the management of Helicobacter pylori infection. Italian Helicobacter pylori Study Group

There are three main types of blood test available for the management of Helicobacter pylori infection: those that detect an antibody response; tests of the pathophysiological state of the stomach; and those that indicate an active infection. Enzyme linked immunosorbent assay (ELISA) based kits are the most numerous of the commercially available tests. Originally the kits used crude antigen preparations but many of the newer kits use a more purified antigen preparation giving increased specificity but a lower sensitivity. The sensitivity, specificity, and predictive values of the tests can also be affected by the population under test and coexistent disease in the patients. Near patient test kits are based on either latex agglutination or immunochromatography. Generally, they have low sensitivities compared with laboratory tests. Commercial western blotting kits have also been developed and are used to detect the presence of specific virulence markers. The exact role of serology in the management of Helicobacter infection has still to be defined, although there is evidence that, used as a screening procedure, it can reduce endoscopy cost and workload. Gastrin and pepsinogen blood concentrations may provide valuable information on the pathophysiological state of the stomach--for example, the presence of inflammation or gastric atrophy. A combination of serology and serum concentrations of gastrin and pepsinogen may be used effectively to detect serious gastroduodenal disease in patients.

cagA positive and negative Helicobacter pylori strains are simultaneously present in the stomach of most patients with non-ulcer dyspepsia: relevance to histological damage

BACKGROUND/AIMS

Infection with Helicobacter pylori strains harbouring the cagA gene (cagA+) is associated with an increased risk of developing peptic ulcer and gastric cancer. The aim of this study was to assess whether H pylori isolates with different cagA status were present in patients with non-ulcer dyspepsia, and whether a variable cagA status is relevant to histological gastric mucosal damage and glandular cell proliferation.

METHODS

Well separated H pylori colonies (between 2 and 25) from primary plates, per gastric area, for each of 19 patients with non-ulcer dyspepsia were examined for cagA by hybridisation. Western blotting was used to examine both representative colonies for CagA expression and the patients' sera for antibody response to CagA. Glandular gastric cell proliferation was assessed immunohistochemically.

RESULTS

Of the 747 colonies examined, 45.3% were cagA+. All colonies from four patients were cagA+, and all colonies from two patients were cagA-. In 13 patients (68%) both cagA+ and cagA- colonies were found. CagA expression of isolates corresponded to their cagA status. H pylori strains with different CagA molecular masses were present in three patients. Results based on all 19 patients studied showed that the prevalence of cagA+ colonies in areas with mucosal atrophy associated or not with intestinal metaplasia (67.9%) was significantly higher than in normal mucosa (44.7%) and mucosa from patients with chronic gastritis (44.0%) (p < 0.001). High levels of cell proliferation were associated with histological atrophy with or without intestinal metaplasia, but not with the possession of cagA by organisms colonising the same mucosal sites.

CONCLUSIONS

Most patients with nonulcer dyspepsia are infected by both cagA+ and cagA- H pylori colonies. The cagA status of infecting organisms may play a role in the development of atrophy and intestinal metaplasia.

Most Helicobacter pylori-infected patients have specific antibodies, and some also have H. pylori antigens and genomic material in bile: is it a risk factor for gallstone formation?

Bile may contain a 130-kDa protein endowed with aminopeptidase activity and the ability to promote cholesterol crystallisation. As >90% of H. pylori strains have a similar peptidase activity, and half the isolates express a 110- to 140-kDa antigen, the CagA protein, we investigated a possible association between H. pylori infection and gallstones, and the presence in bile samples of factors related to H. pylori that could increase cholesterol crystallization. The prevalence of H. pylori infection was 82.1% in 112 patients with gallstones and 80.3% in 112 controls (NS). Fifteen bile samples out of 23 specimens from infected patients (65.2%) contained anti-CagA antibodies. A approximately 60-kDa antigen only reacting with an anti-CagA antibody was found in five bile samples (21.7%) from 23 infected patients. One bile sample (4.1%) contained ureA and cagA genes of H. pylori. The homology of CagA with the N-terminal sequence of aminopeptidase N was very low. We concluded that the presence of specific antibody to H. pylori in most bile samples tested and of an H. pylori putative antigen in a discrete number of cases may represent factors that increase the risk of gallstone formation.

Helicobacter pylori and diminished growth in children: is it simply a marker of deprivation?

Helicobacter pylori is an accepted gastroduodenal pathogen and has recently been investigated for possible implications in non gastroenterological diseases such as growth impairment coronary heart disease and diabetes. Infection by cytotoxic, i.e., CagA or VacA positive strains seems more likely to lead to more serious gastroduodenal diseases compared to infection by non cytotoxic strains, but the possible role of CagA or VacA positive strains in non gastroenterological diseases has not been investigated. Aim of the present study was to evaluate the prevalence of Helicobacter pylori infection as well as CagA and VacA positivity in three paediatric populations auxologically normal, hyposomic and diabetic children. Sera from a total of 522 children (auxologically normal: 246, hyposomic: 164, diabetic: 112) were analyzed by a novel Recombinant ImmunoBlot Assay-Strip Immunoblot Assay--RIBA SIA--which contain individual band for whole Helicobacter pylori lysate and recombinant CagA and VacA. The overall seroprevalence of reactivities against Helicobacter pylori lysate, CagA and VacA were: 7.3%, 9.3%, 6.9% vs 11.6%, 7.9%, 8.5% vs 14.3%, 13.4%, 8% (p = NS) in auxologically normal, hyposomic and diabetic children, respectively. Summarizing, we found a similar prevalence of reactivity against both whole Helicobacter pylori lysate as well as recombinant CagA and VacA between auxologically normal, hyposomic and diabetic children. Our data do not support a possible role of Helicobacter pylori in diminished growth in children.

What is the role of Helicobacter pylori in complicated ulcer disease?

The role of Helicobacter pylori in the pathogenesis of duodenal and gastric ulcer and ulcer recurrence is widely known. Bleeding, perforation, and obstruction represent the most serious, potentially life-threatening manifestations of ulcer disease (hemorrhage in 15%-20%). The lifetime prevalence of perforation and obstruction is much lower (approximately 5% and 2%, respectively). Despite improved diagnostic and therapeutic options, bleeding-related mortality rates remain at 6%-7% in the United States and between 4% and 14% in Europe. H. pylori and nonsteroidal anti-inflammatory drugs are now recognized as the two primary causes of ulcer disease. Eradication of H. pylori in patients with uncomplicated ulcers results in recurrence rates of < 10%, suggesting that eradication of H. pylori in patients with bleeding ulcers may virtually prevent recurrence of both the disease and its complications. Although the prevalence of H. pylori infection is almost 100% in duodenal and 80%-90% in gastric ulcer patients not using nonsteroidal anti-inflammatory drugs, the prevalence of the organism in bleeding duodenal and gastric ulcers does not reach 70% and 60%, respectively, which may be due to false-negative test results.

Family treatment of symptomatic children with Helicobacter pylori infection

BACKGROUND

Familial clustering of Helicobacter pylori infection has been reported. We tested the hypothesis that simultaneously treating all Helicobacter pylori positive family contacts of infected symptomatic children results in lower treatment failure.

METHODS

Relatives of 47 children (index) with Helicobacter pylori gastritis had endoscopy to assess prevalence of infection in first degree cohabiting relatives. Controls included 60 children with dyspepsia and Helicobacter pylori gastritis whose infected family contacts were not treated. Index children, siblings younger than 18 years of age and control children received a 2-week course of amoxicillin and tinidazole. Parents of index children and their siblings over 18 years of age received a 2-week course of Colloidal Bismuth Subcytrate and tinidazole. The eradication rate in index children and their relatives was compared to controls whose infected family contacts were not treated.

RESULTS

Helicobacter pylori was found in 67% of 31 siblings younger than 18, in 82% of 22 siblings older than 18 years, and in 87% of 92 parents. Endoscopy, repeated four to six weeks after the end of treatment, showed Helicobacter pylori eradication in 94% of children and siblings younger than 18, and in 70% of parents and siblings over 18 years in the family treatment group, compared with 75% of control children (p < .01).

CONCLUSIONS

The high prevalence of the infection in family members suggests that person-to-person spread of Helicobacter pylori takes place. Furthermore our results show that if (or when) required, simultaneous treatment given to the whole family results in lower treatment failure, since it may promote compliance to treatment.

High prevalence of Helicobacter pylori in liver cirrhosis: relationship with clinical and endoscopic features and the risk of peptic ulcer

In 153 consecutive patients with cirrhosis we assessed: (1) the prevalence of IgG to Helicobacter pylori and compared it with that found in 1010 blood donors resident in the same area; and (2) the relationships of IgG to Helicobacter pylori with clinical and endoscopic features and with the risk of peptic ulcer. The IgG to Helicobacter pylori prevalence of cirrhotics was significantly higher than in blood donors (76.5% vs 41.8%; P < 0.0005) and was not associated with sex, cirrhosis etiology, Child class, gammaglobulins and hypertensive gastropathy. In both groups, the prevalence of IgG to Helicobacter pylori was significantly higher in subjects over 40. Among patients with cirrhosis a significantly higher prevalence of Helicobacter pylori was found in patients with previous hospital admission (P = 0.02) and/or upper gastrointestinal endoscopy (P = 0.01) and patients with peptic ulcer (P = 0.0004). Multivariate analysis identified increasing age and male sex as risk factors for a positive Helicobacter pylori serology and no independent risk factors for peptic ulcer. The high prevalence of Helicobacter pylori-positive serology found in the present series is related to age and sex and might also be explained by previous hospital admissions and/or upper gastrointestinal endoscopy. Our results do not confirm the role of Helicobacter pylori as risk factor for peptic ulcer in patients with liver cirrhosis.

Prospective screening of dyspeptic patients by Helicobacter pylori serology: a safe policy? The Italian Helicobacter pylori Study Group

BACKGROUND AND STUDY AIMS

Endoscopic screening of all dyspeptic patients is not cost-effective, nor is it feasible in many health-care delivery systems. To select the most appropriate candidates, various preendoscopic screening strategies have been proposed, some of which include Helicobacter pylori serology and patient age. We assessed the value of these two criteria in preendoscopic screening of a large series of dyspeptic patients, and compared the results obtained in a referral hospital (university center with an extensive H. pylori research program) with those in nonreferral hospital (participating centers that did not have such a program).

PATIENTS AND METHODS

Blood samples for determination of anti-H. pylori IgG antibody were collected from patients with uninvestigated dyspepsia undergoing endoscopy at one referral hospital and in 93 nonreferral hospitals throughout Italy. For IgG antibody assay, an in-house enzyme-linked immunosorbent assay (ELISA) technique was used in the referral hospital, while a commercial kit was used in the nonreferral hospitals.

RESULTS

A total of 1638 patients were evaluated at the referral hospital (845 men and 793 women, mean age 46.1 years, range 18-89), and 3281 at the nonreferral hospitals (1718 men and 1563 women, mean age 48.8, range 18-96), respectively. If endoscopy had not been performed in patients who were seronegative for H. pylori and younger than 45 years, 19% versus 17.5% of the tests would have been avoided in the referral and nonreferral hospitals, respectively, while six of 304 ulcers (2%) and no cancers would have been missed versus 35 of 557 ulcers (6.3%) and two of 557 cancers (0.3%).

CONCLUSIONS

A screening strategy based on age and H. pylori serology is a valid means of selecting dyspeptic patients for endoscopy; however, the policy needs further refinement for use in nonreferral hospitals.

A serologic survey of Helicobacter pylori infection in 3281 Italian patients endoscoped for upper gastrointestinal symptoms. The Italian Helicobacter Pylori Study Group

AIM

To assess the seroprevalence of Helicobacter pylori infection in a large series of patients with upper gastrointestinal symptoms referred for their first upper gastrointestinal endoscopy, and to evaluate any association with disease.

METHODS

A large survey of 3281 dyspeptic patients undergoing their first endoscopic examination was undertaken, involving 93 centres in Italy. A blood sample was taken from each participant, for measuring IgG antibodies against H. pylori using a commercially available kit, and two biopsies of the antral gastric mucosa were obtained for evaluating a Giemsa-stained specimen.

RESULTS

Endoscopic macroscopic diagnoses included normal mucosa (25.3%), gustroduodenitis (51.6%), gastric and duodenal ulcers (3.7 and 14.9%, respectively) and other conditions, including gastric cancer (0.8%). Overall, the seroprevalence result was 71.3% with a strong positive association with increasing age and male sex and a negative one with educational level. According to endoscopic diagnoses, the association with H. pylori seropositivity was highest for duodenal and gastric ulcer (multivariate odds ratio: 6.1 and 2.2) and lowest for carcinoma. The comparison between the results of serology and the single Giemsa-stained specimen showed good reliability of H. pylori IgG, particularly in a subgroup (n = 2056) for which the interpretation was performed by a single dedicated pathologist: sensitivity and specificity were 92 and 78%, respectively.

CONCLUSION

Commercial IgG serology is a reliable tool for the assessment of H. pylori infection in large-scale multicentre surveys. A very high seroprevalence among dyspeptic patients was confirmed, particularly in the presence of peptic disease. Factors associated with the infection were very similar to those usually reported in the general population, but male patients showed a significantly higher prevalence.

Usefulness of serology in preendoscopic screening. The Italian Helicobacter pylori Study Group

BACKGROUND

Over the last 20 years, upper gastrointestinal endoscopy has become the investigation of choice for patients with symptoms referrable to the upper gastrointestinal tract. As the increasing number of patients referred for endoscopy has led to enlarged waiting lists and medical expenses, it has been recommended that preendoscopic screening strategies might identify patients at low risk of having major pathology. These patients could avoid prompt endoscopy and might safely undergo different management. Since the recognition of the major role played by Helicobacter pylori in gastroduodenal pathology, H. pylori serological and demographical features have been proposed as part of preendoscopic screening strategies in dyspeptic patients referred to endoscopy, in an attempt to reduce endoscopic workload and medical expenses.

METHODS

We evaluate data presented in the literature and aim to give interpretations possibly helpful in the clinical practice.

RESULTS

The analysis of the endoscopic findings showed that applying a preendoscopic strategy based on age and H. pylori status in local hospitals without a specific interest in H. pylori research would have meant missing a proportion of relevant pathology: 35 of 557 (6.3%) peptic ulcers (24 duodenal and 11 gastric ulcers) and two gastric cancers (0.3%).

CONCLUSIONS

Although we do understand the need to increase the cost-effectiveness of endoscopy and realize that considering age and H. pylori status could help to get to this target, we conclude that similar preendoscopic screening strategies must be refined further before being adopted on a large scale.

Prevention with sucralfate gel of NSAID-induced gastroduodenal damage in arthritic patients

OBJECTIVES

To evaluate the efficacy of a new formulation of sucralfate as gel (Gastrogel) in the short-term prevention of gastroduodenal lesions in arthritic patients receiving nonsteroidal anti-inflammatory drugs.

METHODS

One hundred seven patients with arthritis (M/F 18/89, mean age 55.2 +/- 9.7 yr) enrolled in two centers were considered eligible for the study if initial endoscopy showed the absence of any relevant mucosal damage. Patients were randomly allocated to receive diclofenac 200 mg/day or naproxen 1 g/day plus either sucralfate gel 1 g b.i.d. (N = 53) or identical placebo (N = 54) for 14 days in a randomized double-blind study. Repeated assessment of GI symptoms and endoscopy were performed at the end of the study period.

RESULTS

At final endoscopy the incidence of erosion and the mean endoscopic score for both stomach and duodenum were significantly lower in the sucralfate gel group compared with placebo group (p < 0.05). Both heartburn and epigastric pain were significantly less frequent in patients receiving sucralfate gel than placebo (51 vs 30% and 49 vs 28% for heartburn and epigastric pain, respectively, p < 0.05). No differences were observed in the incidence or in the mean score for nausea. An unexplained difference in the incidence of ulcers was found between the two centers, but in both a similar reduction in the incidence of ulcers was observed between patients receiving sucralfate gel compared with those receiving placebo. The overall difference (8% in sucralfate-treated patients, 28% in patients receiving placebo) of gastroduodenal ulcers was statistically significant (p < 0.05).

CONCLUSIONS

Sucralfate gel reduces both the incidence of acute gastroduodenal mucosal lesions and symptoms in patients with arthritis receiving short-term nonsteroidal anti-inflammatory drugs.

Antigenic mimicry between Helicobacter pylori and gastric mucosa in the pathogenesis of body atrophic gastritis

BACKGROUND & AIMS

The majority of patients with Helicobacter pylori infection have autoantibodies cross-reacting with gastric antigens. In this study, the relation between autoantibody status, histopathology of body mucosa, and antigenic profile of H. pylori was investigated.

METHODS

One hundred patients were examined for H. pylori infection, body gastritis, and gastric autoantibodies. Balb/c mice were analyzed for serum autoantibodies after immunization with H. pylori from patients with and without atrophic gastritis.

RESULTS

Immunoglobulin G autoantibodies were detected in 57 of the 87 infected patients (65.5%) but in none of the 13 patients without infection and gastritis. The autoreaction involved mainly the luminal surface of glandular cells and secretory canaliculi of parietal cells. The autoantibody status correlated with the presence and degree of inflammation and atrophy of the glands. H. pylori from patients with atrophic gastritis showed a higher capacity to induce autoantibodies than H. pylori from patients with a minimal superficial gastritis. Monoclonal antibodies showed differences in the bacterial expression of cross-reacting determinants.

CONCLUSIONS

H. pylori-mediated autoimmunity is involved in the pathogenesis of chronic atrophic gastritis. The grade of antigenic mimicry of the infecting H. pylori strain plays a role in the progression of chronic gastritis to atrophy.

Serological response to Helicobacter pylori in gastric and non-gastric cancer

1. We aimed to evaluate the seroprevalence of Helicobacter pylori (H. pylori) in gastric cancer, non-gastric cancer and outpatients by ELISA and iso-electric focusing, and to compare histology and serology for H. pylori in gastric cancer and outpatients. 2. In 124 patients with gastric cancer, 78 patients with non-gastric cancer and 110 outpatients, H. pylori seroprevalence was assessed by ELISA and isoelectric focusing. Gastric cancer and outpatients underwent endoscopy with biopsies. 3. Seroprevalence by ELISA was significantly higher in gastric cancer compared with non-gastric cancer (84% versus 56%, P < 0.001) but not with outpatients (84% versus 74%). Iso-electric focusing detection of H. pylori was comparable to ELISA: 85, 51 and 75% in gastric cancer, non-gastric cancer and outpatients respectively. Oligoclonal iso-electric focusing was significantly more frequent in gastric cancer compared with non-gastric cancer and outpatients: 69% versus 45 and 46% respectively, P < 0.01. The reliability of H. pylori detection by antral biopsy was significantly lower in gastric cancer compared with outpatients: 36% versus 74% (P < 0.001). In gastric cancer, ELISA and iso-electric focusing were significantly more reliable than histology in H. pylori detection (84 and 85% versus 36% respectively) (P < 0.001). 4. Serological immune response to H. pylori in gastric cancer, non-gastric cancer and outpatients seems different both quantitatively and qualitatively; serology was more reliable than histology in detection of H. pylori in gastric cancer.

Spectrotypic analysis of antibodies to Helicobacter pylori in patients with antral gastritis and duodenal ulcer

AIMS

To investigate the anti Helicobacter pylori (H pylori) spectrotype associated with (a) antral gastritis and duodenal ulcer; (b) the H pylori eradicating treatment.

METHODS

Spectrotypic analysis was performed by isoelectric focusing and reverse blotting (IEFRB) in a cross sectional study on sera from 70 patients with antral gastritis and duodenal ulcer. In addition, a longitudinal study was performed on 40 of these patients (20 with antral gastritis and 20 with duodenal ulcer) who underwent eradicating treatment.

RESULTS

The cross sectional study showed that the oligoclonal spectrotype was present in 74% of antral gastritis patients and in 85% of duodenal ulcer patients. In only a minority of subjects (23% with antral gastritis and 3% with duodenal ulcer) was a polyclonal spectrotype observed. The longitudinal study showed a reduction in the intensity of the spectrotypic bands in 5/10 antral gastritis patients with eradicated H pylori as opposed to only 2/10 patients without eradication. A reduction was also observed in 6/11 eradicated v 0/9 non-eradicated patients with duodenal ulcer. Collectively, a reduction in the spectrotype was observed in 11/21 patients (52%) who--independently of the disease--underwent H pylori eradication, as opposed to 2/19 of the non-responder patients (10.5%). The polyclonal spectrotype was found exclusively in four patients with antral gastritis, all belonging to the group without eradication of H pylori after eradicating treatment.

CONCLUSIONS

The anti H pylori oligoclonal spectrotype is the most common pattern observed in patients with antral gastritis and duodenal ulcer. After H pylori eradicating treatment the spectrotype does not change qualitatively, but the polyclonal pattern seems to be predictive of a poor response to eradication.

DNA probe hybridisation in microwells using a new bioluminescent system for the detection of PCR-amplified HIV-1 proviral DNA

A new bioluminescent detection system combined with a sandwich DNA hybridisation reaction in microwells has been developed for the detection of human immunodeficiency virus type 1 (HIV-1) provirus DNA amplified by the polymerase chain reaction (PCR). First, a fragment of the HIV-1 gag gene was amplified. The amplified DNA fragments were denatured and hybridised to a capture probe immobilised in microwells and to a biotinylated detection probe. A streptavidin-pyruvate kinase conjugate could then react on the biotinylated probe and the kinase activity detected by means of the luciferin-luciferase system, with production of a bioluminescent signal. This sandwich assay followed by a bioluminescent reaction detected as little as 7 amol of target DNA. The bioluminescent assay detected 5 HIV copies generated after one round of PCR, even if no band was seen on an agarose gel. The assay was applied to the detection of HIV-proviral DNA in peripheral blood mononuclear cells after one round of PCR and allowed to clearly identify a positive sample as compared to nested PCR.