Improved Performance of a Rapid Office-Based Stool Test for Detection of Helicobacter pylori in Children before and after Therapy

A modified version of a rapid office based one-step monoclonal immunoassay for detection of Helicobacter pylori antigen in stool samples from children was evaluated against biopsy specimen-based methods and compared to a monoclonal enzyme immunoassay using the same antigen. Blinded stool samples from 185 children (0.3 to 18.2 years) were investigated at the time of upper endoscopy prior to anti-H. pylori therapy; 62 children were H. pylori infected and 123 noninfected according to predefined reference standards. Samples obtained 6 to 8 weeks after anti-H. pylori therapy were available from 58 children (3.8 to 17.7 years) and were compared to results of the [¹³C]urea breath test (14/58 were positive). The rapid stool tests were performed by two independent readers. Of 243 rapid tests performed, 1 (0.4%) was invalid for technical reasons. Equivocal results (very weak line) were reported 16 times by reader 1 and 27 times by reader 2. When equivocal results were considered positive, the two observers agreed on 76 positive and 160 negative results and disagreed on 7 samples (2.9%). The sensitivity was 90.8% for reader 1 and 85.5% for reader 2, and the specificity was 91.0% and 93.4%, respectively. The monoclonal enzyme immunoassay revealed a sensitivity and specificity of 94.7% and 97.6%, respectively. The modified chromatographic immunoassay is a good alternative in settings or situations when the monoclonal enzyme immunoassay or the [¹³C]urea breath test are not available or feasible. In order to improve sensitivity, very weak lines should be considered positive test results.Several noninvasive methods are available for the diagnosis of H. pylori infection (5, 14). Serological tests are not appropriate, since they cannot distinguish between a present and previous infection and, in addition, they have a low sensitivity in children younger than 12 years of age (6, 13). The [¹³C]urea breath test (UBT) is the preferred noninvasive diagnostic tool and gives excellent performance for both adults and children, but specificity decreases in very young and mentally disabled children who are not able to cooperate with the test procedure (10, 11, 25). So far, tests for detection of H. pylori antigen in stool samples are the only noninvasive diagnostic tools which do not show an age dependence for the diagnostic accuracy (14, 15). This makes stool tests very attractive, particularly for young children and for epidemiological studies. Several tests have been developed, but validation studies showed differences in performance. An enzyme immunoassay (EIA) based on polyclonal antibodies that was developed by the Meridian Company has been validated in several studies, with controversial results (17, 20, 24). Lack of accuracy is obviously related to intertest variability (19). In contrast, EIA based on monoclonal antibodies showed consistently excellent results, with very high sensitivity and specificity in both children and adults (15, 21). A meta-analysis with head-to-head comparison has judged the monoclonal EIA superior to the polyclonal EIA (8).Recently, we reported on the performance of a one-step monoclonal chromatographic immunoassay for detection of H. pylori antigen in stool samples from symptomatic children compared to the results of a well-established monoclonal EIA using the same antigen, namely, the catalase of H. pylori (22). Evaluation against biopsy specimen-based diagnostic methods showed a moderate sensitivity but a good specificity. After publication of the data, the manufacturer modified the tests. The aim of this study was to evaluate this new version of the rapid office-based one-step stool test in symptomatic children against invasive diagnostic methods and to compare the results with those of the monoclonal EIA.     

Serological Methods for Diagnosis of Helicobacter pylori Infection and Monitoring of Eradication Therapy

 Several methods can be used to diagnose Helicobacter pylori infection. Invasive methods include detection of the bacterium in gastric biopsy specimens by culture, immunohistochemistry, rapid urease tests, or the polymerase chain reaction. Noninvasive or less invasive detection methods include the urea breath test and serological methods. The urea breath test is based on the detection of ¹³CO₂ or ¹⁴CO₂ in breath, produced by bacterial urease in the stomach after labelled urea is swallowed. Serological methods are based on the detection of Helicobacter pylori-specific antibodies in serum, saliva, or urine. In this review, the performance and diagnostic value of several serological methods, such as enzyme immunoassay, rapid office-based assays, and Western blot, will be discussed in relation to biopsy-based methods and the urea breath test. In addition, the value of serological assays for monitoring eradication of Helicobacter pylori infection following treatment will be discussed. The diagnostic performance of properly evaluated serological assays is comparable to that of biopsy-based methods and the urea breath test. To monitor eradication of Helicobacter pylori infection following therapy, quantitative enzyme immunoassays can be used, especially in patients with high pretreatment antibody titres.     

Helicobacter pylori Infection in Infants and Toddlers in South America: Concordance between [13C]Urea Breath Test and Monoclonal H. pylori Stool Antigen Test

Accurate noninvasive tests for diagnosing Helicobacter pylori infection in very young children are strongly required. We investigated the agreement between the [¹³C]urea breath test ([¹³C]UBT) and a monoclonal ELISA (HpSA) for detection of H. pylori antigen in stool. From October 2007 to July 2011, we enrolled 414 infants (123 from Brazil and 291 from Peru) of ages 6 to 30 months. Breath and stool samples were obtained at intervals of at least 3 months from Brazilian (n = 415) and Peruvian (n = 908) infants. [¹³C]UBT and stool test results concurred with each other in 1,255 (94.86%) cases (kappa coefficient = 0.90; 95% confidence interval [CI] = 0.87 to 0.92). In the H. pylori-positive group, delta-over-baseline (DOB) and optical density (OD) values were positively correlated (r = 0.62; P < 0.001). The positivity of the tests was higher (P < 0.001; odds ratio [OR] = 6.01; 95% CI = 4.50 to 8.04) in Peru (546/878; 62.2%) than in Brazil (81/377; 21.5%) and increased with increasing age in Brazil (P = 0.02), whereas in Peru it decreased with increasing age (P < 0.001). The disagreement between the test results was associated with birth in Brazil and female gender but not with age and diarrhea. Our results suggest that both [¹³C]UBT and the stool monoclonal test are reliable for diagnosing H. pylori infection in very young children, which will facilitate robust epidemiological studies in infants and toddlers.     

Evaluation of a novel rapid one-step immunochromatographic assay for detection of monoclonal Helicobacter pylori antigen in stool samples from children

A new rapid one-step immunochromatographic test using monoclonal antibodies for detection of Helicobacter pylori antigen in stool in children was evaluated on coded stool samples from 159 children (mean age, 9.7 +/- 5.0 years; 118 from Munich, 41 from Vienna): 86 children were H. pylori infected defined by positive culture and/or > or =2 other positive tests ([13C]urea breath test, histology, rapid urease test), and 73 children showed concordant negative results. Seventy-nine patients (12.1 +/- 3.8 years; 42 from Munich; 37 from Vienna) were tested 6 to 8 weeks after anti-Helicobacter pylori therapy with urea breath test and stool test. In Munich, all 160 tests (118 pre- and 42 posttreatment) were independently read by two observers. Equivocal results were excluded for calculation of sensitivity and specificity but were considered as false to assess accuracy. The two observers in Munich agreed in 63 out of 65 positive and 89 out of 95 negative results, while eight times (5.0%) they judged the test as equivocal. Pretreatment and posttreatment results for sensitivity were 88.1% (79.2 to 94.1) and 88.9% (51.8 to 99.7), specificity 88.1% (77.8 to 94.1) and 93.9% (85.2 to 98.3), and accuracy 83.5% and 81.5%, respectively. We conclude that the new monoclonal immunochromatographic quick test shows a good interobserver agreement, but equivocal results occur in 5%. Performance is comparable before and after therapy. The test may become a good alternative in children in settings where a [13C]urea breath test or a reliable enzyme immunoassay stool test are not available.     

Evaluation of the novel Helicobacter pylori ClariRes real-time PCR assay for detection and clarithromycin susceptibility testing of H. pylori in stool specimens from symptomatic children

The aim of the present study was to evaluate the Helicobacter pylori ClariRes assay (Ingenetix, Vienna, Austria) for the detection of H. pylori infection and the simultaneous clarithromycin susceptibility testing of the H. pylori isolates in stool samples from 100 symptomatic children. The results obtained by this novel biprobe real-time PCR method were directly compared with the results obtained from histological examination of gastric biopsy specimens, culturing, the [13C]urea breath test, and a monoclonal antibody-based stool antigen enzyme immunoassay (EIA). Fecal specimens from all 54 children who were shown to be noninfected by "gold standard" tests gave true-negative PCR results (specificity, 100%). Of the remaining 46 individuals with a positive H. pylori status, 29 were found to be positive by real-time PCR (sensitivity, 63%). For these 29 cases, the H. pylori ClariRes assay confirmed all results from phenotypic clarithromycin susceptibility testing by Etest. In summary, this investigation demonstrates that detection of Helicobacter DNA in stool samples by real-time PCR is a difficult task and that this method cannot replace the stool antigen EIA (sensitivity, 95.7%) for the accurate diagnosis of H. pylori infection in children.     

Use of a receiver operating characteristic in the evaluation of two commercial enzyme immunoassays for detection ofHelicobacter pylori infection

Two novel commercial IgG enzyme immunoassay (EIA) systems based on acid-glycine-extracted (Pyloriset IgG EIA, Orion Diagnostica) or fast protein liquid chromatography-purified (Cobas Core Anti-H. pylori EIA, Roche Diagnostic Systems)Helicobacter antigens were evaluated in a prospective study involving 127 patients. All patients underwent upper endoscopy with biopsy, and biopsies were examined for the presence ofHelicobacter pylori by a rapid urease test, microscopy and culture. Of the 71 patients found to be infected withHelicobacter pylori, 69 (97.2 %) and 65 (91.5 %) tested positive with the Cobas Core and Pyloriset test, respectively. A detailed receiver operating characteristic analysis of the two tests showed that the Cobas Core assay was more sensitive and specific at every possible cut-off level; gave a better resolution of individual results, indicating a greater fine-sensitivity; and had no grey zone compared to a large grey zone encompassing 13.4 % of the serum samples tested with the Pyloriset EIA. The Cobas Core assay appears to be a valuable tool for epidemiological purposes as well as for pre-endoscopic screening of dyspeptic patients.     

Detection of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> in bioptates of gastric mucosa of patients with gastritis and gastric ulcers using real-time PCR

Helicobacter pylori is currently believed to play an important role in the pathogenesis of gastritis, gastric and duodenal ulcers, and stomach cancer. The ability of H. pylori to colonize gastric mucosa and cause inflammation is determined by genetic factors, three of which are the best studied: the pathogenicity factors CagA and VacA and the adhesion factor BabA. We developed primer systems and probes for real-time polymerase chain reaction (RT PCR), which allowed us to detect H. pylori in specimens and to perform typing of H. pylori virulence factors CagA, VacA, and BabA. Comparison of two H. pylori diagnostic techniques, histological studies of bioptates and RT PCR, demonstrated the superiority of RT PCR in specificity and sensitivity. Typing of H. pylori demonstrated that 70–80% of strains had the cagA⁺/vacA s1 genotype and 10–20% had the cagA/vacA s2 genotype; babA was detected in 75–85% of all strains. H. pylori typing data did not reveal any correlations between the pathogenicity factors CagA and VacA or the adhesion factor BabA with severity of infection.     

Production and Application of New Monoclonal Antibodies Specific for a Fecal Helicobacter pylori Antigen

The aim of the present study was to establish monoclonal antibodies that could be used to produce a diagnostic test composed of one kind of monoclonal antibody recognizing a fecal Helicobacter pylori antigen. The need to develop such a test arose from disadvantages of the diagnostic test that uses a polyclonal antibody or plural kinds of monoclonal antibodies, such as the lower specificity for H. pylori antigen and the difficulty of reproduction with consistent quality. Mice were immunized with sonicated cells of the coccoid form of H. pylori, and fecal samples from H. pylori-positive subjects were screened by a direct sandwich enzyme immunoassay (EIA) for antibody production from 32 hybridoma clones. The three stable clones produced antibodies (21G2, 41A5, and 82B9) that reacted with the same soluble antigen. Gel filtration chromatography showed that the molecular masses of the cellular antigen and the fecal antigen were the same, 260 kDa. The antigen was labile in response to sodium dodecyl sulfate and heat treatments. A single-step direct sandwich EIA using a single monoclonal antibody, 21G2, was developed. The EIA could detect the antigen in 41 H. pylori clinical isolates and in fecal samples from seven H. pylori-positive subjects. Several kinds of Helicobacter species (Helicobacter felis, Helicobacter hepaticus, Helicobacter mustelae, and Helicobacter cinaedi) except H. pylori, major bacteria in feces (Campylobacter jejuni, Bacteroides vulgatus, Bifidobacterium breve, Bifidobacterium infantis, and Escherichia coli), and fecal samples from six H. pylori-negative subjects showed negative results. These results indicate that the new monoclonal antibodies and the new specific EIA would be useful as a noninvasive method of diagnosis of H. pylori infection.     

Evaluation of Immunological Rapid Urease Testing for Detection of Helicobacter pylori

 The aim of this study was to evaluate in clinical specimens the immunological rapid urease test (IRUT), a new diagnostic system for detection of Helicobacter pylori which employs a monoclonal antibody against Helicobacter pylori urease. Helicobacter pylori urease adsorbed on a solid-phase tip coated with a monoclonal antibody against Helicobacter pylori urease after 15 min of incubation with a gastric mucus sample solution was measured by the pH change of the urea solution inside the tip. The detection limit of Helicobacter pylori urease using this system was determined and compared with that of a commercially available rapid urease test. Clinical evaluation of the system was performed in 155 patients. The IRUT could detect 0.25 milli-international units (mIU) of Helicobacter pylori urease per milliliter in less than 20 min. If a patient with at least one positive result in a standard test for Helicobacter pylori was considered to be Helicobacter pylori positive, the sensitivity, specificity, positive and negative predictive values of the system were calculated as 95.2%, 98.9%, 98.4% and 96.8%, respectively. However, 10 of 19 Helicobacter pylori-positive patients in whom the pH change was less than 0.1 had negative results in at least one of the standard tests, whereas the IRUT correctly detected Helicobacter pylori in all but 3 of these 19 patients. The IRUT accurately determined the Helicobacter pylori status of 75 (98.7%) of 76 patients who had completed treatment. This system has high sensitivity for the detection of Helicobacter pylori, especially in patients with low urease activity.     

Detection of Helicobacter pylori in Stool Specimens by PCR and Antigen Enzyme Immunoassay

A highly sensitive seminested PCR assay to detect Helicobacter pylori DNA in feces was developed. PCR with stool specimens and a novel antigen enzyme immunoassay (EIA) for H. pylori detection in feces were evaluated as diagnostic tools and in follow-up with samples from 63 infected and 37 noninfected persons. Infected individuals received eradication therapy followed by endoscopic follow-up 35 days after the start of treatment. At that time, a second stool specimen was obtained from 55 of these patients. Before eradication, the sensitivity of PCR was 93.7% and that of EIA 88.9%. Specificities were 100 and 94.6%, respectively. Of the 55 follow-up specimens, 41 originated from patients from whom H. pylori had been eradicated. Of these, 21 were still positive by PCR and 13 were positive by EIA, indicating that 1 month may be too short a period for follow-up evaluation of stool specimens by these tests.     

Use of a urea breath test versus invasive methods to determine the prevalence ofHelicobacter pylori in zaire

The prevalence ofHelicobacter pylori infection in Zaire was determined by means of a [¹⁴C] urea breath test in 133 asymptomatic subjects, by culture and histological examination of biopsies in 324 consecutive endoscopy patients with chronic epigastric complaints, and by both the breath test and culture/histology in a subset of 92 patients. Sixty healthy Belgian students or hospital laboratory workers were also included for comparison. The prevalence ofHelicobacter pylori was significantly higher in asymptomatic Zairian subjects (77.4 %) than in the Belgians (30 %; p<10^–6). Infection was also acquired much earlier in life in Africans, 66% of the children aged 5 to 9 years already being infected versus none of the Belgian subjects below the age of 20 years. In Zaire, however, the prevalence ofHelicobacter pylori in patients with gastroduodenal disorders (87.5 %) was similar to that in the group of asymptomatic subjects (77.5 %) after adjustment for age and other epidemiological parameters (gender, place of residency, education level, smoking and drinking habits) in a multivariate analysis. The high rate of acquisition ofHelicobacter pylori infection in Zaire emphasizes the need to consider the baseline prevalence ofHelicobacter pylori in a defined population when studying its association with various diseases.     

A Strain-Specific Antigen in Japanese Helicobacter pylori Recognized in Sera of Japanese Children

An enzyme immuno assay (EIA) test based on Japanese strain-derived high-molecular-weight cell-associated proteins (JHM-CAP) was evaluated by comparing with a previously developed EIA test based on a U.S. strain-derived high-molecular-weight cell-associated proteins (HM-CAP). Serum samples of 131 Japanese asymptomatic children (mean age, 5.5 years; range, 0 to 21 years) were tested that include 43 positive and 88 negative children as judged by Helicobacter pylori stool antigen test (HpSA test). Both tests showed comparable and reliable specificities, but the sensitivity of JHM-CAP EIA, at 93.0%, was much higher than that of HM-CAP EIA, at 67.4%. More false-negative results of HM-CAP were obtained in children under 10 years of age. Immunoblot analysis revealed that the JHM-CAP but not the HM-CAP preparation had a 100-kDa antigen recognized by JHM-CAP positive sera. It was concluded that JHM-CAP EIA is highly accurate for the serodiagnosis of H. pylori infection in Japanese young children and that the high sensitivity of JHM-CAP EIA in contrast to HM-CAP EIA is due to the presence of a 100-kDa antigen in Japanese strains that may be recognized by the host immune system at an early stage of infection.     

Eradication of Helicobacter pyloriin clinical situations

Abstract. Helicobacter pylori is prevalent worldwide, especially in developing countries, and is associated with several upper gastrointestinal diseases. Since it is present in over 90% of duodenal ulcer patients, empirical eradication in these patients is often recommended. In gastric ulcer patients, eradication is indicated only after the infection is confirmed. Testing for H. pylori infection should be carried out in patients with peptic ulcer hemorrhage, because eradication has been shown to reduce recurrent bleeding. Both H. pylori and NSAIDs are risk factors for peptic ulceration, and it is reasonable to screen for and eradicate H. pylori infection in peptic ulcer patients taking NSAIDs. H. pylori is a group I carcinogen for gastric adenocarcinoma, and should be eradicated for the primary prevention of this cancer. Eradication of this organism has been reported to result in regression of early low-grade mucosa-associated lymphoid tissue lymphoma. The role of H. pylori infection in the causation of gastroesophageal reflux and non-ulcer dyspepsia is not clearly established. Several tests are available for the diagnosis of H. pylori infection. These include invasive tests, such as histology, culture and urease test, and non-invasive tests, such as serology, urea breath test and stool antigen test. The choice of test is determined by clinical indication, pretest probability of infection, as well as the availability, cost, sensitivity and specificity of the test. H. pylori eradication therapy using proton pump inhibitor with clarithromycin and amoxycillin for 7 days has a success rate of 85–90%. Improved living standard and sanitation are vital in the control of H. pylori transmission and infection. Future development may include the use of vaccines against H. pylori, and therapies specifically targeting cagA strains of the bacteria.     

Evaluation of SD BIOLINE <Emphasis Type="Italic">H. pylori</Emphasis> Ag rapid test against double ELISA with SD <Emphasis Type="Italic">H. pylori</Emphasis> Ag ELISA and EZ-STEP <Emphasis Type="Italic">H. pylori</Emphasis> Ag ELISA tests

Background

Helicobacter pylori antibody titters fall very slowly even after successful treatment. Therefore, tests detecting H. pylori antibody lack specificity and sensitivity. On the other hand, H. pylori stool antigen tests are reported as an alternative assay because of their reliability and simplicity. However, the comparative performance of H. pylori stool antigen tests for detecting the presence of the bacterium in clinical specimens in the study area is not assessed. Therefore, in this study we evaluated the performance of SD BIOLINE H. pylori Ag rapid test with reference to the commercially available EZ- STEP ELISA and SD BIOLINE H. pylori Ag ELISA tests.

Methods

Stool samples were collected to analyse the diagnostic performance of SD BIOLINE H. pylori Ag rapid test kit using SD H. pylori Ag ELISA kit and EZ- STEP ELISA tests as a gold standard. Serum samples were also collected from each patient to test for the presence of H. pylori antibodies using dBest H. pylori Test Disk. Sensitivity, specificity, predictive values and kappa value are assessed. P values <?0.05 were taken statistically significant.

Results

Stool and serum samples were collected from 201 dyspeptic patients and analysed. The sensitivity, specificity, positive and negative predictive values of the SD BIOLINE H. pylori Ag rapid test were: 95.6% (95% CI, 88.8–98.8), 92.5% (95%CI, 89–94.1%), 86.7% (95% CI, 80.5–89.6), and 97.6% (95% CI, 993.9–99.3) respectively.

Conclusion

The performance of SD BIOLINE H. pylori Ag rapid test was better than the currently available antibody test in study area. Therefore, the SD BIOLINE Ag rapid stool test could replace and be used to diagnose active H. pylori infection before the commencement of therapy among dyspeptic patients.

     

Histological examination of ulcer margin for diagnosing Helicobacter pylori infection in patients with gastric ulcers

Biopsy of ulcer margin is routinely performed to exclude malignancy in patients with gastric ulcers, but its utility in diagnosing Helicobacter pylori infection has not yet been fully studied. A cohort of 50 patients with gastric ulcer was prospectively examined. Three tests including histology, rapid urease test, and urea breath test were performed in all patients for diagnosing H pylori infection. Six biopsied specimens from the margin of the gastric ulcer and 1 each specimen from antrum and body of non-ulcer part were obtained for histology using hematoxylin-eosin (H&E) stain. The criterion used for defining H pylori infection was a positive result in at least 2 of the 3 tests. H pylori infection was diagnosed in 27 (54%) of the patients. The diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the histological examination of the ulcer margin were 92.6%, 95.7%, 96.2%, 91.7%, and 94%, respectively. The addition of 1 specimen from the antrum or body or a combination of the 2 specimens did not increase the diagnostic yields of those for histological examination of ulcer margin alone. The diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for the rapid urease test were 96.3%, 100%, 100%, 95.8%, and 98%, respectively, and the corresponding values for the urea breath test were 88.9%, 87%, 88.9%, 87%, and 88%. We performed Giemsa stain for the 3 patients with false-negative and false-positive results of histological examination of ulcer margin using H&E stain, and all were positive for H pylori infection. In conclusion, histological examination of the ulcer margin using hematoxylin-eosin stain was quite accurate and useful for diagnosing H pylori infection in patients with gastric ulcers. A special stain is required when the diagnosis of H pylori infection is questionable on routine H&E staining.     

Evaluation of a Single-Step Serological Assay for Laboratory Diagnosis of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Infection

A rapid, single-step, in-laboratory qualitative test for the detection of IgG antibodies to Helicobacter pylori in serum (TestPack Plus; Abbott Laboratories, Germany) was evaluated. This test may be used as an alternative to enzyme immunoassays (EIAs). Of 153 adult patients, 110 were defined as Helicobacter pylori positive and 43 as Helicobacter pylori negative by the gold standard, a combination of three tests. The performance characteristics of the TestPack Plus, i.e. sensitivity, specificity, and positive and negative predictive values, were not significantly different from the corresponding values obtained with an EIA used for comparative purposes, the Pyloriset EIA-G test (Orion Diagnostica, Finland). The high positive predictive value (93%) of the TestPack Plus single-step serological test makes it a valuable tool for rapid in-laboratory screening purposes, especially in countries with a high prevalence of Helicobacter pylori infection. Electronic Publication     

Evaluation of Helicobacter pylori eradication by triple therapy plus Lactobacillus acidophilus compared to triple therapy alone

The purpose of this study was to evaluate the influence of adding Lactobacillus acidophilus to a triple regimen for Helicobacter pylori eradication in untreated patients with peptic ulcers or ulcer-scars. This was a pre-randomized, single-blind, interventional, treatment-efficacy study with active controls and parallel-assignment, set in Coimbra, Portugal, on 62 consecutive H. pylori-positive untreated adults with peptic ulcers or ulcer-scars, diagnosed by gastroduodenoscopy, with pre-treatment direct Gram-staining and culture of gastric biopsies. The first 31 patients received esomeprazole 20 mg, amoxicillin 1000 mg and clarithromycin 500 mg (EAC), all b.i.d., for 8 days. The remaining 31 added L. acidophilus, 5 × 10⁹ organisms per capsule, 3 + 2 i.d. for 8 days (EACL). The main outcome measure was ¹³C urea breath test (UBT), ≥6 weeks after completion of therapy. Successful eradication (UBT-negativity after treatment), was similar in both groups (EAC = 80.6%; EACL = 83.9%, p = 0.740) by both intention-to-treat and per-protocol analysis. The non-eradicated strains were susceptible in vitro to both antibiotics. Adding L. acidophilus to EAC triple therapy did not increase H. pylori eradication rates. Considering the cost and the burden of ingesting five extra capsules daily, supplementing the EAC therapy with L. acidophilus, at this dose, shows no benefit. Further studies with different dosages and duration of treatment, and other probiotics or probiotic combinations are required to improve eradication.     

Posttreatment Follow-Up of Helicobacter pylori Infection Using a Stool Antigen Immunoassay

The Helicobacter pylori stool antigen enzyme immunoassay (HpSA) was evaluated during posttreatment follow-up of patients in a country with a very high prevalence of H. pylori infection. From among 273 dyspeptic individuals (18 to 55 years) initially recruited from a shantytown in Lima, Peru, 238 participants who met the inclusion criteria and were suspected to be H. pylori positive based on ¹⁴C urea breath test (UBT) results underwent endoscopy. Participants with endoscopy-proven infections received standard eradication therapy and were monitored by UBT and HpSA at 1 month following treatment and at 3-month intervals for 9 months posttreatment. A second endoscopy was performed if UBT results showed evidence of treatment failure or H. pylori recurrence. Biopsy results were considered the “gold standard” in all analyses. Among patients who underwent endoscopy, HpSA had a pretreatment sensitivity of 93%. Two-hundred thirty patients completed the treatment regimen, of whom 201 (93%) were considered to have had successful treatment outcomes based on a negative follow-up UBT. Thirty-two patients with UBT-defined treatment failures or H. pylori recurrences at any point during the 9-month follow-up underwent a second endoscopy. In the posttreatment setting, HpSA had an overall sensitivity of 73% and a specificity of 67%. Agreement between UBT and HpSA diminished throughout the follow-up. Among 14 participants in whom HpSA remained positive at 1 month following treatment despite UBT evidence of treatment success, 12 (86%) became HpSA negative within 3 months posttreatment. Although this study confirmed the validity of the HpSA in the initial assessment of dyspeptic patients, the test demonstrated a reduced overall accuracy in the detection of treatment failures and H. pylori recurrences during 9 months of posttreatment follow-up. Furthermore, in some patients it may take up to 3 months after successful eradication for antigen shedding to diminish to levels within the negative HpSA range.     

Performance of Native and Recombinant Antigens for Diagnosis of Helicobacter pylori Infection

 The aim of this study was to evaluate the performance of three antigenic preparations for serological diagnosis of Helicobacter pylori infection: (i) native antigens from Helicobacter pylori strain N6 or its aflagellated isogenic mutant N6flbA ^–, or an acellular extract (antigen AgFA) from a pool of six clinical strains; (ii) recombinant antigens consisting of CagA fused to MS2 polymerase and HspA or recombinant UreA and UreB fused to the maltose-binding protein, and (iii) the preparations provided with two commercial kits, the Cobas Core (Roche Diagnostic Systems, France) and the Pylori Stat (BioWhittaker, Belgium). All preparations were used in an enzyme immunoassay to test 92 sera from dyspeptic patients for whom the status of Helicobacter infection was established. Sensitivities were higher (90 to 100%) for the native antigens and the commercial kits than for the recombinant antigens. Specificities were higher than 90%, except with UreA + UreB (42%). The most useful antigens were those extracted from strains N6 and N6flbA ^–.     

Liquid culture medium for the rapid cultivation of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> from biopsy specimens

The goal of this study was to develop a liquid culture medium for the rapid isolation, cultivation, identification and subsequent antibiotics susceptibility testing of Helicobacter pylori directly from biopsy specimens. Five liquid media were tested: Ham’s F-12, Brucella broth, tryptic soybroth, brain heart infusion broth and Mueller-Hinton broth. After optimisation of the medium, it was applied in order to investigate biopsy samples from 150 patients with gastro-duodenal disorders and compared with traditional culture methods, microscopy and an H. pylori-specific TaqMan real-time polymerase chain reaction (PCR). The most reliable and rapid growth of H. pylori, even at a small inoculum size, was obtained in Ham’s F-12 medium with 5% horse serum. The developed system allowed the primary isolation of H. pylori in clinical samples and provided 87% sensitivity and 100% specificity.