The Inappropriateness of Using Rifampicin E-Test to Predict Rifabutin Resistance in Helicobacter pylori.

BACKGROUND: The aim of this study was to evaluate the rifamycin cross-resistance in Helicobacter pylori, and whether the use of rifampicin E-test strips to screen H. pylori rifabutin resistance is appropriate. METHODS: A total of 89 H. pylori isolates were included. Rifampicin minimum inhibitory concentrations (MICs) were obtained by E-test, while the MICs for rifapentine, rifaximin, and rifabutin were determined by agar dilution method. The rifamycin resistance rates based on different breakpoints were compared. Isolates with high-level rifampicin resistance were subjected to whole-genome sequencing. RESULTS: A wide distribution of MICs (mostly in the range 0.125-8 mg/L) was observed for rifampicin, rifapentine, and rifaximin. Using MIC >1, ≥ 4, and > 4 mg/L as the breakpoints, resistance rates to rifampicin/rifapentine/rifaximin were 60.4%/48.3%/38.2%, 28.1%/25.8%/23.6%, and 15.7%/16.9%/7.9%, respectively. However, the rifabutin MICs of all the tested H. pylori isolates were extremely low (≤0.016 mg/L). Applying MIC ≥ 0.125 mg/L as the breakpoint, rifabutin resistance was nil. No mutation was found in the rpoB gene sequences of the 2 isolates with high-level rifampicin resistance. CONCLUSIONS: There is a lack of cross-resistance between rifabutin and other rifamycins in H. pylori. The use of rifampicin E-test to predict H. pylori rifabutin resistance is inappropriate.

Association of serum pepsinogens and gastrin-17 with Helicobacter pylori infection assessed by urea breath test.

Background: Association of gastric atrophy or cancer with levels of serum pepsinogens, gastrin-17 and anti-Helicobacter pylori IgG antibody have been extensively studied. However, the association of serum pepsinogen and gastrin-17 with H. pylori infection has not been studied in a large population. Aim: To investigate the impact of H. pylori infection on serum levels of pepsinogens and gastrin-17. Methods: A total of 354, 972 subjects who underwent health check-ups were included. Serum levels of pepsinogens and gastrin-17 were measured using the enzyme-linked immunosorbent assay. H. pylori infection was detected using 14C-urea breath test (UBT). Multivariable logistic regression analysis was used to investigate the association of serum pepsinogen and gastrin-17 with H. pylori infection. Results: H. pylori prevalence was 33.18% in this study. The mean levels of pepsinogens and gastrin-17 were higher, while the mean pepsinogen-I/II ratio were lower among H. pylori-positive than -negative subjects. In H. pylori-positive subjects, pepsinogen and gastrin-17 levels correlated positively, whereas the pepsinogen-I/II ratio correlated negatively with UBT values (e.g., the mean serum level of pepsinogen-I in subjects with UBT values in the range of 100-499dpm, 500-1499dpm, and ≥1500dpm was 94.77 ± 38.99, 102.77 ± 43.59, and 111.53 ± 47.47 ng/mL, respectively). Compared with H. pylori-negative subjects, the adjusted odds ratio (aOR) of having pepsinogen-I ≤ 70 ng/mL in the three H. pylori-positive but with different UBT value groups was 0.31 (p<0.001), 0.16 (p<0.001), and 0.08 (p<0.001), respectively; while the aOR of having G-17>5.70 pmol/L was 4.56 (p<0.001), 7.43 (p<0.001), and 7.12 (p<0.001). This suggested that H. pylori-positive subjects with higher UBT values were less likely to have pepsinogen-I ≤70 ng/mL (a serum marker for gastric atrophy), but more likely to have gastrin-17 >5.70 pmol/L (a marker for peptic ulcer). Conclusions: H. pylori-positive subjects with higher UBT values are unlikely to have gastric atrophy, but may have greater risk of severe gastritis or peptic ulcers. Our study suggests that H. pylori-positive patients with high UBT values may benefit the most from H. pylori eradication.

Need for standardization and harmonization of Helicobacter pylori antimicrobial susceptibility testing.

BACKGROUND AND AIMS: As with other infectious diseases, Helicobacter pylori eradication regimens should be guided by susceptibility testing to achieve excellent success rate, especially in the era of high antibiotic resistance. However, susceptibility testing for H. pylori is rarely performed, which can be partly ascribed to the current lack of standardization of testing methods and the lack of unified consensus on the antibiotic resistance breakpoints. The aim of this review was to call for an international consensus on standardization and harmonization of H. pylori susceptibility testing. METHODS: We summarize and compare the advantages and disadvantages of four different phenotypic antimicrobial susceptibility testing (AST) methods (agar dilution, E-test, disk diffusion, and broth microdilution) and the molecular susceptibility testing method for H. pylori. RESULTS: The standard phenotypic testing methods and the molecular testing methods have their own advantages and disadvantages. Compared to the standard phenotypic methods, the molecular testing method does not require successful H. pylori culture, and therefore, is much more rapid and convenient for clinical use. However, the currently available molecular testing method is only suitable for detecting clarithromycin and quinolone susceptibility profiles in H. pylori. Although the standard AST is time-consuming, it is currently the only way to test the susceptibility of H. pylori to all the commonly used antibiotics. CONCLUSION: To make H. pylori susceptibility testing become a clinical routine, an international consensus on standardization and harmonization of H. pylori AST is needed. Future efforts are needed for optimizing broth culture of H. pylori, and developing commercial AST plates for achieving high throughput and automated susceptibility testing for H. pylori.

Noninvasive Diagnosis of Irritable Bowel Syndrome via Bowel Sound Features: Proof of Concept.

INTRODUCTION: Irritable bowel syndrome (IBS) is a common and debilitating disorder estimated to affect approximately 11% of the world's population. Typically, IBS is a diagnosis of exclusion after patients undergo a costly and invasive colonoscopy to exclude organic disease. Clinician's and researchers have identified a need for a new cost-effective, accurate, and noninvasive diagnostic test for IBS. METHODS: Using a diagnostic case-control study, we explored the use of bowel sounds to characterize IBS with a view to diagnostic use. We recruited participants with an existing clinical diagnosis of IBS or healthy (asymptomatic) digestive systems. We recorded bowel sounds for 2 hours after fasting and then for 40 minutes after a standard meal. RESULTS: We here report our results including our accuracy in characterizing IBS-related bowel sounds and differentiation between participants with IBS and healthy participants. Leave-one-out cross-validation of our model developed using the first 31 IBS and 37 healthy participants gave 90% sensitivity and 92% specificity for IBS diagnosis. Independent testing using the next 15 IBS and 15 healthy participants demonstrated 87% sensitivity and 87% specificity for IBS diagnosis. CONCLUSIONS: These preliminary results provide proof of concept for the use of bowel sound analysis to identify IBS. A prospective study is needed to confirm these findings. TRANSLATIONAL IMPACT: Our belt and model offer hope of a new approach for IBS diagnosis in primary practice. Combined with screening tests for organic disease, it would offer greater confidence to patients and could reduce the burden of unnecessary colonoscopies for health care systems and patients.

Advances in Acoustic Signal Processing Techniques for Enhanced Bowel Sound Analysis.

With the invention of the electronic stethoscope and other similar recording and data logging devices, acoustic signal processing concepts and methods can now be applied to bowel sounds. In this paper, the literature pertaining to acoustic signal processing for bowel sound analysis is reviewed and discussed. The paper outlines some of the fundamental approaches and machine learning principles that may be used in bowel sound analysis. The advances in signal processing techniques that have allowed useful information to be obtained from bowel sounds from a historical perspective are provided. The document specifically address the progress in bowel sound analysis, such as improved noise reduction, segmentation, signal enhancement, feature extraction, localization of sounds, and machine learning techniques. We have found that advanced acoustic signal processing incorporating novel machine learning methods and artificial intelligence can lead to better interpretation of acoustic information emanating from the bowel.

Development of a tetracycline-inducible gene expression system for the study of Helicobacter pylori pathogenesis.

Deletion mutants and animal models have been instrumental in the study of Helicobacter pylori pathogenesis. Conditional mutants, however, would enable the study of the temporal gene requirement during H. pylori colonization and chronic infection. To achieve this goal, we adapted the Escherichia coli Tn10-derived tetracycline-inducible expression system for use in H. pylori. The ureA promoter was modified by inserting one or two tet operators to generate tetracycline-responsive promoters, named uPtetO, and these promoters were then fused to the reporter gfpmut2 and inserted into different loci. The expression of the tetracycline repressor (tetR) was placed under the control of one of three promoters and inserted into the chromosome. Conditional expression of green fluorescent protein (GFP) in strains harboring tetR and uPtetO-GFP was characterized by measuring GFP activity and by immunoblotting. The two tet-responsive uPtetO promoters differ in strength, and induction of these promoters was inducer concentration and time dependent, with maximum expression achieved after induction for 8 to 16 h. Furthermore, the chromosomal location of the uPtetO-GFP construct and the nature of the promoter driving expression of tetR influenced the strength of the uPtetO promoters upon induction. Integration of uPtetO-GFP and tetR constructs at different genomic loci was stable in vivo and did not affect colonization. Finally, we demonstrate tetracycline-dependent induction of GFP expression in vivo during chronic infection. These results open new experimental avenues for dissecting H. pylori pathogenesis using animal models and for testing the roles of specific genes in colonization of, adaptation to, and persistence in the host.

Comparing the genomes of Helicobacter pylori clinical strain UM032 and Mice-adapted derivatives.

BACKGROUND: Helicobacter pylori is a Gram-negative bacterium that persistently infects the human stomach inducing chronic inflammation. The exact mechanisms of pathogenesis are still not completely understood. Although not a natural host for H. pylori, mouse infection models play an important role in establishing the immunology and pathogenicity of H. pylori. In this study, for the first time, the genome sequences of clinical H. pylori strain UM032 and mice-adapted derivatives, 298 and 299, were sequenced using the PacBio Single Molecule, Real-Time (SMRT) technology. RESULT: Here, we described the single contig which was achieved for UM032 (1,599,441 bp), 298 (1,604,216 bp) and 299 (1,601,149 bp). Preliminary analysis suggested that methylation of H. pylori genome through its restriction modification system may be determinative of its host specificity and adaptation. CONCLUSION: Availability of these genomic sequences will aid in enhancing our current level of understanding the host specificity of H. pylori.

Helicobacter pylori: present status and future prospects in Japan.

The discovery of Helicobacter pylori has already changed the natural history of peptic ulcer disease, with most patients being cured at their first presentation. Similarly, the incidence of gastric cancer and other diseases related to H. pylori are likely to be greatly reduced in the near future. Isolation of the spiral intragastric bacterium H. pylori totally reversed the false dogma that the stomach was sterile, and it taught us that chronic infectious disease can still exist in modern society. Helicobacter pylori's unique location, persistence, and evasion of the immune system offer important insights into the pathophysiology of the gut. Also, the fact that it was overlooked for so long encourages us to think "outside the box" when investigating other diseases with obscure etiologies. We should consider such provocative scientific ideas as bridges to the future disease control.

Overview: Helicobacter pylori and extragastric disease.

Isolation of the gastric spiral bacterium Helicobacter pylori totally reversed the false dogma that the stomach was sterile. In addition to its causal role in peptic ulceration, the newly identified bacterium has now been implicated in other gastric and even extragastric diseases, including chronic atrophic gastritis, gastric MALT lymphoma, gastric cancer, functional dyspepsia, idiopathic thrombocytopenic purpura (ITP), iron deficiency anemia, chronic urticaria, ischemic heart disease, and others. The majority of the reports are anecdotal, epidemiologic, or eradication studies, but there are also relevant in vitro studies. ITP represents one disease showing a strong link with H pylori infection. There are also accumulating data on the role of H pylori infection in iron deficiency anemia and ischemic heart disease. In summary, the association between H pylori infection and other extragut diseases is still controversial but worthy of further investigation.