Recurrence of Helicobacter pylori infection after successful eradication: nature and possible causes

Recurrence of Helicobacter pylori infection after successful eradication occurs and is associated with relapse of gastroduodenal diseases. The aims of this paper were to assess the incidence and identify the nature and possible causes of recurrence of the infection. A broad-based Medline search was performed to identify all related publications addressing recurrence of the infection between 1986 and 1995. The 12-month recurrence rate varied among the different studies from 0 to 41.5%. A few studies showed 18- to 24-month recurrence rates, which ranged between 0 and 21.4%. Limited data, obtained using molecular fingerprinting techniques, have shown that in most cases recurrence is due to recrudescence of the original strain; a few cases appear to be due to reinfection with a new strain. Recrudescence is most likely during the first 12 months after apparent eradication. Despite the high sensitivity and specificity of the available individual tests for detecting H. pylori infection in untreated patients, no technique alone is sensitive enough to monitor eradication when the four-week-rule definition for eradication is used. A combination of two or more techniques increases sensitivity. Sensitivity and specificity are increased when biopsies are taken from both gastric antrum and corpus. The best treatments have the lowest recurrence rates and recurrence is rare when the eradication rate is over 90%. Individual susceptibility and reexposure to H. pylori are suggested as two major causes of reinfection.

Clarithromycin resistance in Helicobacter pylori: prevalence in untreated dyspeptic patients and stability in vitro

Susceptibilities to clarithromycin and metronidazole of 444 Helicobacter pylori isolates cultured from antral biopsies of 444 dyspeptic patients were determined by disc diffusion tests (15 mu g disc for clarithromycin, 5 mu g disc for metronidazole). Susceptibility of 46 of these isolates to erythromycin (5 mu g disc) was also tested. Minimal inhibitory concentrations (MICs) of clarithromycin for 42 selected isolates were determined by a plate dilution method. A zone diameter of 30 mm was defined as a 'cut-off' size differentiating susceptibility and resistance of the organism to clarithromycin, by comparing results obtained with the two methods. Of the 444 isolates, 424 (95.5%) were highly sensitive to clarithromycin, with zone diameters ranging from 30 to 98 mm. Twenty isolates (4.5%) were defined as resistant to clarithromycin, with zone diameters ranging between 6 and 28 mm. The incidence of clarithromycin resistance was similar in men and women and in different age groups, and was not significantly different between patients with peptic ulcer and non-ulcer dyspepsia. Among the 444 isolates, 168 (37.8%) were metronidazole resistant. There was cross resistance between clarithromycin and erythromycin, but not between clarithromycin and metronidazole. Stability of clarithromycin resistance was evaluated by the disc diffusion test and confirmed by the plate dilution method. Among the 20 clarithromycin-resistant isolates, nine (45%) reverted to be sensitive after 25 subcultures on drug-free agar. The findings in this study indicate that the incidence of clarithromycin-resistant H. pylori in untreated dyspeptic patients is low. Cross-resistance occurs between macrolides and resistance to clarithromycin in some strains is reversible.

Symptomatic response to lansoprazole predicts abnormal acid reflux in endoscopy-negative patients with non-cardiac chest pain

AIM

To determine whether symptomatic response to lansoprazole predicts abnormal acid reflux in endoscopy-negative patients with non-cardiac chest pain.

METHODS

Patients who complained of chest pain, but had normal coronary angiography, were asked to undergo upper endoscopy. Those without gastric and oesophageal lesions were recruited for 24-h ambulatory oesophageal pH monitoring, and were randomly given lansoprazole 30 mg or placebo, both daily for 4 weeks. Chest pain symptoms were recorded before and 1 month after treatment on a locally validated questionnaire. The symptom score was calculated by multiplying the severity and frequency of the symptom, and symptom improvement was defined as > 50% reduction in symptom score.

RESULTS

Overall, 68 patients, 36 on lansoprazole and 32 on placebo, completed the trial. The symptom score was reduced significantly in both groups (P < 0.001). In the lansoprazole group, more patients with than without abnormal reflux showed symptom improvement (92% vs. 33%; odds ratio = 22; 95% confidence interval, 2.3-201.8; chi2 = 10.9; P = 0.001), giving a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 92%, 67%, 58%, 94% and 75%, respectively. In the placebo group, the rates of symptom improvement were similar between those with and without abnormal reflux (33% vs. 35%, P = N.S.).

CONCLUSIONS

Treatment with lansoprazole is a useful test in diagnosing endoscopy-negative gastro-oesophageal reflux disease in Chinese patients with non-cardiac chest pain.

Recrudescence of Helicobacter pylori after apparently successful eradication: novel application of randomly amplified polymorphic DNA fingerprinting

The aim of this study was to find out if reinfection or recrudescence accounted for the recurrence of Helicobacter pylori infections after apparent eradication of the bacterium. Three hundred and twenty patients were treated with colloidal bismuth subcitrate (120 mg four times daily for four weeks), metronidazole and tetracycline (400 mg and 500 mg, respectively, thrice daily for the first week). H pylori was eradicated four weeks after the end of treatment as assessed by the rapid urease test, histological examination, Gram staining, and culture. However, the infection recurred in 29 (9.1%) of the patients one year after apparent eradication. Pre and posteradication isolates from five patients were available. DNA was extracted and used for restriction endonuclease analysis with Hind III and Hae III, and for polymerase chain reaction (PCR) based randomly amplified polymorphic DNA fingerprinting with a combination of two 10 nucleotide primers. Sodium dodecyl sulphate polyacrylamide gel electrophoretic analysis was performed also. Randomly amplified polymorphic DNA fingerprinting was unique in that it yielded highly discriminatory fingerprints, which showed that the pretreatment and recurrent isolates obtained from each of the five patients were indistinguishable from one another. This shows that recurrence of H pylori infection is probably caused by recrudescence and that the discriminatory power of randomly amplified polymorphic DNA fingerprinting is a practicable and discriminatory typing scheme for H pylori.

Standardization of disk diffusion test and its clinical significance for susceptibility testing of metronidazole against Helicobacter pylori

Susceptibilities of 121 clinical Helicobacter pylori strains to metronidazole were determined by both a 5-micrograms metronidazole disk diffusion test and a plate dilution method in duplicate and after different periods of incubation. The distribution of MICs of metronidazole against H. pylori among the strains was found to be bimodal. The diameters of inhibitory zones obtained by the disk diffusion test and the MICs obtained by the plate dilution method correlated well, especially after 4 days of incubation (r = 0.77). An inhibitory zone diameter of 20 mm was found to correspond to a MIC of 8 micrograms/ml and is recommended as a suitable zone for differentiating susceptibility and resistance with a 5-micrograms metronidazole disk. Three interpretive categories of susceptibility results were defined; strains with inhibitory zone diameters of more than 26 mm were defined as susceptible (MIC, < 4 micrograms/ml), strains with zone diameters of 20 to 26 mm were deemed intermediate (MIC, 4 to 8 micrograms/ml), and those with zone diameters of less than 20 mm were deemed resistant (MIC, > 8 micrograms/ml). Furthermore, 76 H. pylori-positive patients with duodenal ulcers or nonulcer dyspepsia were treated with a 1 week of triple therapy (colloidal bismuth subcitrate, metronidazole, and tetracycline). H. pylori strains were isolated before treatment from antral biopsies from those patients, and the metronidazole susceptibilities of the strains were determined by the disk diffusion test. H. pylori status was evaluated again 4 weeks after completion of treatment. The eradication rates for susceptible, intermediate, and resistant strains were 95.9% (47 of 49), 62.5% (5 of 8), and 52.6% (10 of 19), respectively. It is included that the 5-micrograms disk diffusion test is easy to perform and gives final results similar to those of the plate dilution method. The three interpretive categories of susceptibility may be of benefit for clinical choice of chemotherapy in eradicating H. pylori.

Effect of Helicobacter pylori on apoptosis and apoptosis related genes in gastric cancer cells

BACKGROUND/AIMS

Helicobacter pylori induces the apoptosis of gastric epithelial cells in vivo and in vitro. However, the molecular mechanism has not been clarified. The aim of this study was to investigate the effect of H pylori on the apoptosis of gastric epithelial cells and the expression of apoptosis related genes in vitro.

METHODS

Human gastric adenocarcinoma SGC-7901 cells were co-cultured with a cytotoxic H pylori strain, NCTC 11637, at various densities ranging from 3.2 x 10(4) to 1.0 x 10(8) colony forming units (CFU)/ml for 48 hours. Apoptosis in gastric cells was determined by transmission electron microscopy, Hoechst 33258 fluorochrome staining, and flow cytometry. The expression of apoptosis related proteins, Bcl-2, Bax, and c-Myc, was measured by an immunohistochemical method, and c-Myc mRNA expression was determined by the reverse transcription-polymerase chain reaction.

RESULTS

Helicobacter pylori induces morphological changes typical of apoptosis. Both fluorochrome staining and flow cytometry showed that the apoptotic index began to increase when H pylori were at a density of > 1.6 x 10(4) CFU/ml, and in a density dependent manner (p < 0.01; one way ANOVA). The expression of the Bax and c-Myc proteins and of c-Myc mRNA was increased, whereas Bcl-2 expression was decreased after co-culture for 48 hours.

CONCLUSIONS

Helicobacter pylori induced apoptosis in gastric epithelial cells is mediated by altered expression of the products of the Bcl-2, Bax, and c-Myc genes.

Alternative and rescue treatment regimens for Helicobacter pylori eradication

Eradication therapy has been incorporated into clinical practice. The regimens currently recommended for first-line treatment include a 2-week bismuth-based triple therapy (mainly in developing countries), a 1 - 2 week proton pump inhibitor (PPI)-based triple therapy and a 1-week ranitidine bismuth citrate (RBC)-based triple therapy. However, these regimens fail to eradicate Helicobacter pylori in up to 20% of patients due to poor compliance, inadequate treatment duration, smoking, old age and bacterial resistance to nitroimidazoles and/or macrolides in particular. Therefore, alternative regimens that avoid nitroimidazoles and/or macrolides or overcome bacterial resistance to these drugs, improve compliance, minimise side effects and/or reduce costs have been evaluated. One-week quadruple therapy, which adds a PPI or histamine receptor 2-blocker to bismuth-based triple therapy, usually achieves an eradication rate of 90% when used as an alternative first-line therapy but the efficacy decreases when used as a rescue therapy. Several new triple therapies that may be used as alternative and/or rescue therapies have been evaluated. Among these are furazolidone-based (furazolidone plus an antibiotic and a bismuth salt, a PPI or RBC), fluoroquinolone-based (levofloxacin or moxifloxacin plus an antibiotic and a PPI) and ecabet sodium-based (ecabet plus two antibiotics) triple therapies. Recently, rifabutin has been used in combination with a PPI and amoxycillin as a rescue therapy, with satisfactory eradication rates. In addition, a number of new antimicrobial agents are currently under investigation in in vitro studies but the clinical values of these agents needs to be confirmed.

Enhanced cultivation of Helicobacter pylori in liquid media

AIMS

To evaluate a technique for culture of Helicobacter pylori in large quantities of liquid media and to determine the factors that could influence the results.

METHODS

Fifteen clinical isolates of H pylori and a reference strain of H pylori NCTC11637 were used to evaluate a method to cultivate the organism in 100 ml liquid medium comprising brain heart infusion broth with 5% horse serum and 0.25% yeast extract. Tissue culture flasks containing the inoculated liquid medium were placed in a CO2 incubator with 5% CO2 for 2 hours and then incubated in a shaking incubator at 120 rpm.

RESULTS

All the clinical isolates and the reference strain grew in the broth, although only a moderate growth of the reference strain occurred. Inoculum size significantly influenced the kinetics of growth of H pylori in the liquid medium. Vancomycin, nalidixic acid, and amphotericin B, used to suppress contamination, did not affect growth of H pylori in the medium. CO2 was essential for H pylori to grow or survive in the liquid medium. Incubation with CO2 in a CO2 incubator for 30 minutes or 2 hours did not affect the results.

CONCLUSIONS

H pylori can be cultivated in large quantities of brain heart infusion broth with 5% horse serum and 0.25% yeast extract. Initial inoculum concentrations influence the kinetics of H pylori growth in the liquid medium. Vancomycin, nalidixic acid, and amphotericin B can be used as selective antimicrobial agents. CO2 is essential for initial growth of H pylori in liquid media. The findings in this study may provide a useful, reproducible, and simple method for biochemical, molecular, and physiological studies of H pylori, when those require large quantities of the organism.

Inhibition of human telomerase reverse transcriptase by nonsteroidal antiinflammatory drugs in colon carcinoma

BACKGROUND

Telomerase activation, which is observed in most human cancers, plays an important role in carcinogenesis. Human telomerase reverse transcriptase (hTERT) is a subunit of telomerase that is essential for telomerase activity. The aim of the study was to investigate whether nonsteroidal antiinflammatory drugs (NSAIDs) inhibit telomerase activity and hTERT.

METHODS

Four colon carcinoma cell lines, HT-29, COLO205, CRL-2134, and SW1116, were used in the experiments. Polymerase chain reaction-based telomeric repeat amplification (TRAP) enzyme-linked immunosorbent assay (ELISA) was used to measure telomerase activity in the cells after treatment with aspirin, indomethacin, or SC-236 (a specific cyclooxygenase-2 [COX-2] inhibitor). Expression of hTERT mRNA and protein was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The dual luciferase reporter assay was performed to identify the potential cis-response elements to NSAIDs in the promoter region of hTERT.

RESULTS

Aspirin, indomethacin, and SC-236 inhibited telomerase activity in HT-29, COLO205, and CRL-2134 cell lines, but not in the SW1116 cell line. NSAIDs inhibited hTERT mRNA and protein expression through suppression of hTERT transcriptional activity. The hTERT promoter fragment -145 to -330 basepairs (bp) upstream of the ATG starting site was sufficient to respond to the NSAID-induced inhibitory effect and the inhibition was COX-2-independent.

CONCLUSION

NSAIDs inhibit telomerase activity at hTERT transcriptional, mRNA, and protein levels in colon carcinoma cells. The hTERT promoter fragment -145 to -330 bp may be the cis-response element to NSAIDs.

Perceptions of Chinese Biomedical Researchers Towards Academic Misconduct: A Comparison Between 2015 and 2010

Publications by Chinese researchers in scientific journals have dramatically increased over the past decade; however, academic misconduct also becomes more prevalent in the country. The aim of this prospective study was to understand the perceptions of Chinese biomedical researchers towards academic misconduct and the trend from 2010 to 2015. A questionnaire comprising 10 questions was designed and then validated by ten biomedical researchers in China. In the years 2010 and 2015, respectively, the questionnaire was sent as a survey to biomedical researchers at teaching hospitals, universities, and medical institutes in mainland China. Data were analyzed by the Chi squared test, one-way analysis of variance with the Tukey post hoc test, or Spearman's rank correlation method, where appropriate. The overall response rates in 2010 and 2015 were 4.5% (446/9986) and 5.5% (832/15,127), respectively. Data from 15 participants in 2010 were invalid, and analysis was thus performed for 1263 participants. Among the participants, 54.7% thought that academic misconduct was serious-to-extremely serious, and 71.2% believed that the Chinese authorities paid no or little attention to the academic misconduct. Moreover, 70.2 and 65.2% of participants considered that the punishment for academic misconduct at the authority and institution levels, respectively, was not appropriate or severe enough. Inappropriate authorship and plagiarism were the most common forms of academic misconduct. The most important factor underlying academic misconduct was the academic assessment system, as judged by 50.7% of the participants. Participants estimated that 40.1% (39.8 ± 23.5% in 2010; 40.2 ± 24.5% in 2015) of published scientific articles were associated with some form of academic misconduct. Their perceptions towards academic misconduct had not significantly changed over the 5 years. Reform of the academic assessment system should be the fundamental approach to tackling this problem in China.

Effects of Washed Microbiota Transplantation on Serum Uric Acid Levels, Symptoms, and Intestinal Barrier Function in Patients with Acute and Recurrent Gout: A Pilot Study

INTRODUCTION

Gut dysbiosis has been reported to be closely associated with gout. Washed microbiota transplantation (WMT) is considered as an effective way to restore a healthy gut microbiota with less adverse events than the conventional fecal microbiota transplantation. In this study, we aimed to evaluate the effects of WMT on serum uric acid levels, symptoms, and the intestinal barrier function in patients with acute and recurrent gout.

METHODS

We performed a pilot study of WMT for acute and recurrent gout. The primary outcome was the changes in the serum uric acid level and gout symptoms. The secondary outcomes included the changes in levels of diamine oxidase (DAO), D-lactic acid, and endotoxin.

RESULTS

Eleven patients received WMT treatment. The averaged serum uric acid levels in patients with gout reduced after WMT (p = 0.031), accompanied with a decrease in the frequency and duration time of acute gout flares (p < 0.01). The levels of DAO, D-lactic acid, and endotoxin were higher in patients than in healthy donors (p < 0.05). After WMT treatment, the levels of DAO and endotoxin decreased (p < 0.05).

CONCLUSIONS

WMT is effective for reducing serum uric acid levels and improving gout symptoms in patients with gout and contributes to improve their impaired intestinal barrier function.

Culture of Helicobacter pylori under aerobic conditions on solid media

The aim of the present study was to culture Helicobacter pylori under aerobic conditions and to investigate the characteristics of the organism when cultured aerobically. Most (22 of 23) of the Helicobacter pylori isolates grew under aerobic conditions, but with reduced viable cell counts. Blood agar was more suitable than chocolate agar. The morphological and enzymatic characteristics as well as the protein profiles of each organism were identical under aerobic and microaerophilic conditions. However, haemolysis of Helicobacter pylori was delayed under aerobic conditions. The MIC of metronidazole was slightly lower for some strains under aerobic conditions. These findings indicate that Helicobacter pylori is not only a microaerophilic organism but also adapts to aerobic conditions, which may have some important implications in microbiological and epidemiological studies.

Transportation of Helicobacter pylori cultures by optimal systems

Cultures of Helicobacter pylori on chocolate agar slants in bijou bottles and on chocolate agar plates inside BBL Campy Pouches were mailed from Dublin to Galway, Ireland; Bordeaux, France; and Beijing, China. Both systems maintained viability of H. pylori for at least 4 days under mailing conditions. Ninety percent of the isolates on the slants survived for 6 days, but only 30% of the isolates in the pouches survived. When the slants were stored at 4 degrees C after arrival, 50% of the isolates were recoverable 10 days after mailing. Failure of recovery was due to coccoid formation by the organisms. Contamination was not a problem in either system. Chocolate agar slants are considered the more suitable system for transporting H. pylori cultures, especially when transport time longer than 4 days is expected.

Helicobacter pylori infection--current treatment practice

Helicobacter pylori infection, which is present in 30 - 60% of the population in developed countries and in more than 60% in developing countries, is established to be a major cause of gastritis, peptic ulcer disease and gastric cancer. Eradication therapy has been incorporated into clinical practice over the past 15 years. Treatment regimens include a 2 week bismuth-based triple therapy (a bismuth compound plus metronidazole, tetracycline or amoxycillin), a 1 week proton-pump inhibitor (PPI)-based triple therapy and a 1 week ranitidine bismuth citrate (RBC)-based triple therapy (a PPI or RBC plus any two of the three antibiotics, metronidazole, amoxycillin and clarithromycin). These regimens achieve eradication rates of >> 80%. H. pylori resistance to metronidazole and clarithromycin decreases the clinical efficacy of most regimens, despite the high eradication rates for resistant strains achieved by the RBC-triple therapy in some recent trials. The dose of antibiotics (especially clarithromycin) and the duration of treatment may also influence the eradication rate. Doctors' beliefs impact on clinical practice and, thus, influence the clinical application of eradication therapy. Whereas peptic ulcer disease and primary gastric low-grade B-cell mucosa-associated lymphoid tissue lymphoma (MALToma) have become established as definite indications for eradication therapy, there remain controversies surrounding non-ulcer dyspepsia, gastro-oesophageal reflux disease, atrophic gastritis, intestinal metaplasia, use of non-steroidal anti-inflammatory drugs (NSAIDs) and H. pylori-related extradigestive diseases.