Culture of Helicobacter pylori from a gastric string may be an alternative to endoscopic biopsy

Rapid diagnosis and precision treatment of Helicobacter pylori infection in clinical settings

Helicobacter pylori is a gram-negative bacterium that colonizes the stomach of approximately half of the worldwide population, with higher prevalence in densely populated areas like Asia, the Caribbean, Latin America, and Africa. H. pylori infections range from asymptomatic cases to potentially fatal diseases, including peptic ulcers, chronic gastritis, and stomach adenocarcinoma. The management of these conditions has become more difficult due to the rising prevalence of drug-resistant H. pylori infections, which ultimately lead to gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. In 1994, the International Agency for Research on Cancer (IARC) categorized H. pylori as a Group I carcinogen, contributing to approximately 780,000 cancer cases annually. Antibiotic resistance against drugs used to treat H. pylori infections ranges between 15% and 50% worldwide, with Asian countries having exceptionally high rates. This review systematically examines the impacts of H. pylori infection, the increasing prevalence of antibiotic resistance, and the urgent need for accurate diagnosis and precision treatment. The present status of precision treatment strategies and prospective approaches for eradicating infections caused by antibiotic-resistant H. pylori will also be evaluated.

Detection Yield and Tolerability of String Test for Diagnosis of Childhood Intrathoracic Tuberculosis

BACKGROUND

Difficulty to obtain sputum in children complicates diagnosis of intrathoracic tuberculosis (TB). The intragastric string test (ST) used for retrieval of enteric pathogens might be an alternative specimen collection method but requires further evaluation of its utility in TB diagnosis. We conducted a cross-sectional study comparing the TB detection yield and the tolerability of ST and sputum induction (SI) in children.

METHODS

Two ST and SI procedures were performed in children (3-14 years of age) who were clinically suspected of having TB. The string was removed after a 2-hour gastric downtime, and SI was done after a maximum of 20 minutes nebulization with 5% saline solution. LED-fluorescence microscopy and mycobacterial cultures were performed on all specimens, and XpertMTB/RIF assay was performed on stored specimen sediments. Tolerability questionnaires were administered to parents of children.

RESULTS

Of 137 included children (median age: 8.1 years; 33.3% with HIV infection), 14 (10.2%) were diagnosed with TB, 10 (71.4%) by ST and 12 (85.7%) by SI. Among 105 children with both ST and SI performed, 5 (4.8%) versus 4 (3.8%) were smear positive using ST and SI, respectively (McNemar P = 1.00). Nine (8.6%) in each group had positive cultures (P = 1.00). Of 64 children tested with XpertMTB/RIF, 3 (4.7%) of the ST group versus 4 (6.3%) of the SI group were TB positive (P = 1.00). No adverse serious events were reported. ST could not be performed in 22 of 137 (16.1%) children because they were unable to swallow the capsule.

CONCLUSIONS

TB detection yield was comparable between ST and SI. The tolerability of ST in young children might be improved by the reduction of the size of the capsule.

Diagnosis of Helicobacter pylori: Changes towards the Future

Since the first evidence demonstrating the dramatically high incidence of H. pylori infection and the subsequent medical challenges it incurs, health management of H. pylori infection has been a high priority for health authorities worldwide. Despite a decreasing rate of infection in western countries, prevalence of H. pylori infection in developing and in some industrial countries is still very high. Whereas treatment and vaccination against H. pylori is a contemporary issue in medical communities, selective treatment and prior high-throughput screening of the subject population is a major concern of health organizations. So far, diagnostic tests are either elaborative and require relatively advanced medical care infrastructure or they do not fulfill the criteria recommended by the Maastricht IV/Florence consensus report. In this review, in light of recent scientific studies, we highlight current and possible future approaches for the diagnosis of H. pylori. We point out that novel non-invasive tests may not only cover the requirements of gold standard methods in H. pylori detection but also offer the potential for risk stratification of infection in a high throughput manner.

Helicobacter pylori virulence genes detected by string PCR in children from an urban community in northeastern Brazil

The accuracy of a nested PCR in gastric DNA obtained by a string test for the diagnosis of Helicobacter pylori infection in asymptomatic children was 94.0%. The cagA-positive toxigenic vacAs1m1 strains were the most prevalent strains, indicating that this population is colonized early by the strains associated with gastric cancer.

DNA-level diversity and relatedness of Helicobacter pylori strains in shantytown families in Peru and transmission in a developing-country setting

The efficiency of transmission of a pathogen within families compared with that between unrelated persons can affect both the strategies needed to control or eradicate infection and how the pathogen evolves. In industrialized countries, most cases of transmission of the gastric pathogen Helicobacter pylori seems to be from mother to child. An alternative model, potentially applicable among the very poor in developing countries, where infection is more common and the sanitary infrastructure is often deficient, invokes frequent transmission among unrelated persons, often via environmental sources. In the present study, we compared the genotypes of H. pylori from members of shantytown households in Peru to better understand the transmission of H. pylori in developing-country settings. H. pylori cultures and/or DNAs were obtained with informed consent by the string test (a minimally invasive alternative to endoscopy) from at least one child and one parent from each of 62 families. The random amplified polymorphic DNA fingerprints of 57 of 81 (70%) child-mother strain pairs did not match, nor did the diagnostic gene sequences (>1% DNA sequence difference), independent of the child's age (range, 1 to 39 years). Most strains from siblings or other paired family members were also unrelated. These results suggest that H. pylori infections are often community acquired in the society studied. Transmission between unrelated persons should facilitate the formation of novel recombinant genotypes by interstrain DNA transfer and selection for genotypes that are well suited for individual hosts. It also implies that the effective prevention of H. pylori infection and associated gastroduodenal disease will require anti-H. pylori measures to be applied communitywide.

Helicobacter pylori detection and antimicrobial susceptibility testing

The discovery of Helicobacter pylori in 1982 was the starting point of a revolution concerning the concepts and management of gastroduodenal diseases. It is now well accepted that the most common stomach disease, peptic ulcer disease, is an infectious disease, and all consensus conferences agree that the causative agent, H. pylori, must be treated with antibiotics. Furthermore, the concept emerged that this bacterium could be the trigger of various malignant diseases of the stomach, and it is now a model for chronic bacterial infections causing cancer. Most of the many different techniques involved in diagnosis of H. pylori infection are performed in clinical microbiology laboratories. The aim of this article is to review the current status of these methods and their application, highlighting the important progress which has been made in the past decade. Both invasive and noninvasive techniques will be reviewed.

Effectiveness of enterobacterial repetitive intergenic consensus PCR and random amplified polymorphic DNA fingerprinting for Helicobacter pylori strain differentiation

We compared the robustness and discriminatory power of the enterobacterial repetitive intergenic consensus (ERIC) and random amplified polymorphic DNA (RAPD) fingerprinting methods for detecting cases of mixed Helicobacter pylori infection in Peruvian shantytown residents. H. pylori isolates from 63 participants were cultured, and five single colonies and a pool of additional colonies from each participant were analyzed by ERIC-PCR and by RAPD tests with four 10-nucleotide primers (one primer per reaction). There was 94% agreement between the ERIC and RAPD profiles in classifying sets of isolates as uniform versus closely related but not identical versus probably unrelated, indicating a high kappa statistic of 0.8942. Subtle differences in related ERIC or RAPD patterns likely reflect gene transfer between strains, recombination, and/or mutation, whereas markedly different patterns reflect infection by unrelated strains. At least half of infected shantytown residents seemed to carry more than one H. pylori strain, although in 19 of 31 persons, the strains were closely related. Three RAPD tests, each with a different primer, were needed to achieve the sensitivity of one ERIC test. ERIC-PCR constitutes a resource- and time-efficient method for H. pylori strain differentiation.

Validation of string test for diagnosis of Helicobacter pylori infections

The method of recovering Helicobacter pylori DNA or viable cells absorbed on a string that a person has swallowed and that is retrieved an hour later (string test) should be a useful alternative to traditional analysis of cells or DNA obtained by endoscopy, which is invasive, uncomfortable, relatively costly, and ill-suited for community-based and pediatric studies. Here we assayed the sensitivity and validity of the string test versus conventional endoscopic biopsy for detecting and analyzing H. pylori infection. Forty-four people with gastric complaints were studied using both H. pylori culture and urease gene (ureB) PCR. H. pylori organisms cultured from strings and biopsy specimens from the same patients were fingerprinted by the randomly amplified polymorphic DNA (RAPD) method. Biopsy sections were also hematoxylin and eosin and silver stained for H. pylori detection. H. pylori was cultured from 80% of strings and detected by PCR from 91% of strings from participants whose biopsies had been H. pylori positive by culture, PCR, and/or histology. Strains recovered from strings and biopsy specimens yielded identical or closely related RAPD profiles in each of the 24 cases tested. We conclude that the string test is a useful method for H. pylori recovery and analysis when relatively noninvasive procedures are needed.

Methodology and transport medium for collection of Helicobacter pylori on a string test in remote locations

BACKGROUND

Helicobacter pylori can be isolated from patients using the string test but contaminating oral and nasopharyngeal microflora need to be suppressed by rapid plating out onto selective culture media. Recently, use of this diagnostic method was enhanced by using a novel transport medium to collect specimens from subjects in a remote Australian clinic over 1300 km from the laboratory.

METHODS

Retrieved string tests were transported to the laboratory in chilled polystyrene boxes in 5 ml screw-cap bottles with 3 ml of a brain heart infusion broth plus antibiotics. These were 20 g/ml vancomycin, 10 g/ml trimethoprim, 10 g/ml cefsulodin, and 10 g/ml amphotericin B. A comparison was made between subjects who gargled with a chlorhexidine mouthwash before swallowing the string test and those who did not.

RESULTS

Forty-five urea breath test-positive subjects were tested and H. pylori was isolated from 34 of them. Successful culture was achieved from string tests that were in transit for up to 29 hours and where the maximum temperature in the transport box was 14 degrees C. The additional use of a mouthwash had a marked effect on the isolation rate. H. pylori was cultured from 75% of subjects who gargled but only from 39% who did not.

CONCLUSIONS

This methodology and transport medium can broaden the use of the string test to more remote geographic areas where endoscopy is not feasible so that H. pylori isolates may still be obtained for diagnostic and epidemiologic studies. The value of this promising methodology of collection and transport should be assessed in a controlled study.

Breath and string test: a diagnostic package for the identification of treatment failure and antibiotic resistance of Helicobacter pylori without the necessity of upper gastrointestinal endoscopy

AIM

Helicobacter pylori (H pylori) resistance after failed eradication has a major impact on the outcome of a further treatment regimen. The aim of this study was to assess the validity of a non-invasive strategy using the 13C-urea breath test (UBT) and the gastric string test in identifying post-treatment resistance of H pylori.

METHODS

The UBT was routinely performed 4 to 6 wk after H pylori eradication therapy. Forty-two patients (24 females, 18 males, mean age 48 years) with a positive UBT were included in the study. A gastric string test using a capsule containing a 90 cm-long nylon fiber was performed. Before the capsule was swallowed, the free end of the string was taped to the cheek. After one hour in the stomach, the string was withdrawn. The distal 20 cm of the string was inoculated onto an agar plate and processed under micro-aerophilic conditions. Following the string test, upper gastrointestinal endoscopy was performed to obtain gastric biopsies for conventional culture.

RESULTS

H pylori was successfully cultured from the gastric string in 34 patients (81%), but not in 5 patients due to contamination with oropharyngeal flora. H pylori was cultured from the gastric biopsies obtained at endoscopy in 39 patients (93%).

CONCLUSION

The UBT followed by the gastric string test in the case of treatment failure is a valid diagnostic strategy with the aim of determining the post-therapeutic antibiotic resistance of H pylori with little inconvenience to the patient. Upper GI-endoscopy can be avoided in several cases by applying consequently this diagnostic package.

Nitazoxanide in treatment of Helicobacter pylori: a clinical and in vitro study

Nitazoxanide (NTZ) is an antibiotic with microbiological characteristics similar to those of metronidazole but without an apparent problem of resistance. The aim of this study was the prospective evaluation of NTZ given as a single agent in the treatment of Helicobacter pylori infection. Twenty culture-positive patients with dyspepsia who had previously failed at least one course of H. pylori eradication therapy were enrolled. Subjects received 1 g of NTZ twice daily for 10 days. The safety and tolerability of the drug were assessed by physical examination, monitoring of adverse events, and clinical laboratory evaluation. Urea breath tests (UBTs) were performed 6 weeks posttreatment. H. pylori was isolated from UBT-positive patients by the string test or endoscopy with biopsy, and the MICs for these isolates were compared to those for isolates obtained pretherapy. The levels of tizoxanide, the active deacylated derivative of NTZ, were measured in blood, saliva, and tissue from two patients during treatment. The UBT results were positive for all 20 patients after completion of NTZ therapy. The MIC results demonstrated that the NTZ susceptibilities of none of the strains isolated from the patients posttherapy had changed significantly. No major adverse reactions were observed, but frequent minor side effects were observed. In conclusion, NTZ did not eradicate H. pylori when it was given as a single agent.

Evaluation of the string test for the detection of Helicobacter pylori

AIM: Helicobacter pylori can be diagnosed by invasive or non-invasive tests but to obtain bacteria for culture and antibiotic susceptibility testing, an upper GI endoscopy is often required. The string test may be a minimally-invasive alternative method of obtaining H. pylori samples. This study evaluates the sensitivity and specificity of the string test in the diagnosis of H. pylori in comparison with endoscopic means of diagnosis.

METHODS: This was a prospective open comparative study of patients with dyspepsia with endoscopy-based tests as gold standard (defined as a positive CLO test and antral histology). Fasting patients swallowed the encapsulated-string (Entero-test Hp), which was withdrawn after 1 h. The gastric juice from the string was plated onto H. pylori-selective media for culture. Helicobacter pylori was identified by typical colony morphology, gram stain and biochemical test results.

RESULTS: Thirty dyspeptic patients were recruited of whom 21 (70%) were positive for H. pylori according to the gold standard. The sensitivity, specificity, positive predictive value, and negative predictive value for the string test were 38%, 100%, 100% and 41% respectively, and for endoscopic biopsies 81%, 100%, 100%, 69% respectively (P = 0.004). Logistic regression showed that only abundant growth density from endoscopic biopsy cultures to be a predictor of a positive string test (P = 0.018).

CONCLUSION: The string test is an alternative method to endoscopy in obtaining H. pylori but has a low sensitivity compared to endoscopic biopsies.

PCR detection of Helicobacter pylori in string-absorbed gastric juice

Molecular methods for detection of Helicobacter pylori infection have been shown to be highly sensitive in gastric biopsies and cultures. The objective of this work was to compare PCR detection of H. pylori DNA in string-absorbed gastric juice and in gastric biopsies. The study was performed in 47 dyspeptic adult patients undergoing endoscopy, and infection was detected by amplification of a segment of H. pylori ureA gene. Of the 29 patients positive in biopsy analysis, 23 (79%) were also positive in the gastric string. PCR analysis of gastric strings is a sensitive and safe procedure to detect H. pylori when endoscopy is not indicated, and may be of great clinical and epidemiological usefulness in determining effectiveness of eradication therapies, typing virulence genes and detecting antibiotic resistance mutations.

Validation of the string test for the recovery of Helicobacter pylori from gastric secretions and correlation of its results with urea breath test results, serology, and gastric pH levels

The efficacy of the string culture test to isolate Helicobacter pylori from gastric secretions of 28 volunteers was studied. With the urea breath test (UBT) as the "gold standard," the string culture test showed a sensitivity of 75% and a specificity of 100%. The results of string culture did not correlate with the UBT results, with serum antibody levels, or with the pH levels of gastric secretions.