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  1. Ansari S, Yamaoka Y
    Int J Mol Sci, 2020 Oct 08;21(19).
    PMID: 33050101 DOI: 10.3390/ijms21197430
    Helicobacter pylori causes persistent infection in the gastric epithelium of more than half of the world's population, leading to the development of severe complications such as peptic ulcer diseases, gastric cancer, and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Several virulence factors, including cytotoxin-associated gene A (CagA), which is translocated into the gastric epithelium via the type 4 secretory system (T4SS), have been indicated to play a vital role in disease development. Although infection with strains harboring the East Asian type of CagA possessing the EPIYA-A, -B, and -D sequences has been found to potentiate cell proliferation and disease pathogenicity, the exact mechanism of CagA involvement in disease severity still remains to be elucidated. Therefore, we discuss the possible role of CagA in gastric pathogenicity.
  2. Ansari S, Yamaoka Y
    Expert Rev Anti Infect Ther, 2020 10;18(10):987-996.
    PMID: 32536287 DOI: 10.1080/14787210.2020.1782739
    Introduction Helicobacter pylori causes, via the influence of several virulence factors, persistent infection of the stomach, which leads to severe complications. Vacuolating cytotoxin A (VacA) is observed in almost all clinical strains of H. pylori; however, only some strains produce the toxigenic and pathogenic VacA, which is influenced by the gene sequence variations. VacA exerts its action by causing cell vacuolation and apoptosis. We performed a PubMed search to review the latest literatures published in English language. Areas covered Articles regarding H. pylori VacA and its genotypes, architecture, internalization, and role in gastric infection and pathogenicity are reviewed. We included the search for recently published literature until January 2020. Expert opinion H. pylori VacA plays a crucial role in severe gastric pathogenicity. In addition, VacA mediated in vivo bacterial survival leads to persistent infection and an enhanced bacterial evasion from the action of antibiotics and the innate host defense system, which leads to drug evasion. VacA as a co-stimulator for the CagA phosphorylation may exert a synergistic effect playing an important role in the CagA-mediated pathogenicity.
  3. Ansari S, Yamaoka Y
    Toxins (Basel), 2019 Nov 19;11(11).
    PMID: 31752394 DOI: 10.3390/toxins11110677
    Helicobacter pylori colonizes the gastric epithelial cells of at least half of the world's population, and it is the strongest risk factor for developing gastric complications like chronic gastritis, ulcer diseases, and gastric cancer. To successfully colonize and establish a persistent infection, the bacteria must overcome harsh gastric conditions. H. pylori has a well-developed mechanism by which it can survive in a very acidic niche. Despite bacterial factors, gastric environmental factors and host genetic constituents together play a co-operative role for gastric pathogenicity. The virulence factors include bacterial colonization factors BabA, SabA, OipA, and HopQ, and the virulence factors necessary for gastric pathogenicity include the effector proteins like CagA, VacA, HtrA, and the outer membrane vesicles. Bacterial factors are considered more important. Here, we summarize the recent information to better understand several bacterial virulence factors and their role in the pathogenic mechanism.
  4. Graham DY, Yamaoka Y, Malaty HM
    Trans R Soc Trop Med Hyg, 2007 Sep;101(9):849-51.
    PMID: 17658569
    Helicobacter pylori is one of the few remaining major pathogens that accompanied humans on their travels from Africa. A recently published study reports the unexpected finding of a low H. pylori prevalence among pregnant women in Zanzibar (Farag, T.H., Stolzfus, R.J., Khalfan, S.S., Tielsch, J.M., 2007. Unexpectedly low prevalence of Helicobacter pylori infection among pregnant women on Pemba Island, Zanzibar. Trans. R. Soc. Trop. Med. Hyg. 101). The apparent epidemiology of higher prevalence with higher socioeconomic status and decrease with age are unprecedented. As with many 'unexpected' events, a search of the literature reveals evidence of low prevalence populations in Java and Malaysia, with clues dating back to the mid-twentieth century. Why some populations apparently lost H. pylori infection remains an open question. However, the tools needed to resolve the dilemma are readily available and we hope investigators will soon rise to the challenge.
  5. Goh KL, Chan WK, Shiota S, Yamaoka Y
    Helicobacter, 2011 Sep;16 Suppl 1:1-9.
    PMID: 21896079 DOI: 10.1111/j.1523-5378.2011.00874.x
    This review summarizes studies on the epidemiology and public health implications of Helicobacter pylori published in peer-reviewed journals from April 2010 through March 2011. Prevalence rates vary widely between different geographical regions and ethnic groups. An interesting study from the USA identified the degree of African ancestry as an independent predictor of H. pylori infection. Two studies have demonstrated early childhood as the period of transmission of infection and identified an infected sibling as an important risk factor. An oral-oral route of spread has been substantiated with several studies showing the presence of H. pylori in the oral cavity. Studies have shown the presence of H. pylori in drinking water and the role of poor living conditions and sanitation in H. pylori infection, supporting an oral-fecal route of spread. Screening for H. pylori as a gastric cancer pre-screening strategy has been described in Japan, and the importance of H. pylori eradication as a gastric cancer-prevention strategy has now been further emphasized in Japanese guidelines. Two studies have shown a decrease in the burden of dyspepsia and peptic ulcer disease with H. pylori eradication.
  6. Ma ZF, Majid NA, Yamaoka Y, Lee YY
    Front Microbiol, 2016;7:368.
    PMID: 27047479 DOI: 10.3389/fmicb.2016.00368
    Based on the hygiene hypothesis, a low prevalence of Helicobacter pylori (H. pylori) infection may explain the recent high prevalence of allergic diseases including food allergy. However, there are very few studies that investigate the relationship between H. pylori and food allergy.
  7. Ma ZF, Abdul Majid N, Yamaoka Y, Lee YY
    Front Microbiol, 2016;7:1232.
    PMID: 27512393 DOI: 10.3389/fmicb.2016.01232
    [This corrects the article on p. 368 in vol. 7, PMID: 27047479.].
  8. Vilaichone RK, Quach DT, Yamaoka Y, Sugano K, Mahachai V
    Asian Pac J Cancer Prev, 2018 May 26;19(5):1411-1413.
    PMID: 29802708
    Objective: Antibiotic resistance has significantly impact on eradication rates for H. pylori infection and remains
    important cause of treatment failure worldwide including ASEAN countries. The aim of this study was to survey
    the prevalence and antibiotic resistant pattern of H. pylori infection in ASEAN. Methods: This study was a survey among
    26 experts from 9 ASEAN countries including Thailand, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines,
    Singapore and Vietnam whom attended a meeting to develop the ASEAN consensus on H. pylori management in Bangkok
    in November 2015. A questionnaire was sent to each member of the consensus meeting. The detail of the questionnaire
    included information about prevalence of H. pylori infection, facilities to perform H. pylori culture, molecular testing
    for antibiotic resistance and antibiotic resistance rate in their countries. Results: H. pylori infection remain common
    in ASEAN ranging from 20% in Malaysia, 21-54% in Thailand and 69% in Myanmar. Most of ASEAN countries
    can perform H. pylori cultures and antibiotic susceptibility tests except Laos and Cambodia. In ASEAN countries,
    metronidazole resistant H pylori is quite common whereas amoxicillin resistance remain rare. Clarithromycin resistance
    results in a significant decrease in H. pylori eradication rate with clarithromycin-containing regimens. The prevalence of
    clarithromycin resistance varies in ASEAN countries being high in Vietnam (30%) and Cambodia (43%), moderate to high
    in Singapore (17%) and low in Malaysia (6.8%), Philippine (2%) and Myanmar (0%). In Thailand, clarithromycin
    resistance tends to higher in large cities (14%) than in rural areas (~3.7%). Conclusion: ASEAN countries should
    develop a standard protocol for regular susceptibility testing of H. pylori so that clinicians would be better able to
    choose reliably effective empiric therapies. The wide range of antibiotic resistance in ASEAN countries suggests that
    the preferred first line regimen should be depend on the local antibiotic resistance other than single recommendation.
  9. Hsu PI, Yamaoka Y, Goh KL, Manfredi M, Wu DC, Mahachai V
    Biomed Res Int, 2015;2015:278308.
    PMID: 26078943 DOI: 10.1155/2015/278308
  10. Quach DT, Vilaichone RK, Vu KV, Yamaoka Y, Sugano K, Mahachai V
    Asian Pac J Cancer Prev, 2018 Dec 25;19(12):3565-3569.
    PMID: 30583684
    Background: Helicobacter pylori (H. pylori) infection is currently considered as an infectious disease irrespective of symptoms and stage of disease. This study aimed to survey the impact of H. pylori infection and the current management approaches in Southeast Asian countries.
    Materials and methods: This is a survey among 26 experts from 9 Southeast Asian countries (Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand and Vietnam), who attended a meeting to develop the ASEAN consensus on H. pylori management in November 2015.
    Results: The prevalence of H. pylori varied significantly from 20% to 69% among countries, highest in Myanmar and lowest in Malaysia. The rate of H. pylori infection in patients with gastritis, peptic ulcer disease and gastric cancer (GC) also varied significantly, not only among countries but also among regions within the same country. The most common method for H. pylori diagnosis before treatment was rapid urease test, followed by urea breath test. In multi-ethnic countries, some ethnic groups including Chinese, Batak and Minahasanese were considered as having higher risk of GC. There have been no national screening programs for GC in all countries, and a majority of patients with GC were diagnosed in advanced stages with very poor 5-year survival.
    Conclusions: The prevalence of H. pylori infection and its infection rates in related gastrointestinal diseases were significantly different among Southeast Asian countries. The prognosis of patients with GC in the region was very poor. The result of this survey is a platform for future international and regional research collaboration.
  11. Fauzia KA, Miftahussurur M, Syam AF, Waskito LA, Doohan D, Rezkitha YAA, et al.
    Toxins (Basel), 2020 07 24;12(8).
    PMID: 32722296 DOI: 10.3390/toxins12080473
    We evaluated biofilm formation of clinical Helicobacter pylori isolates from Indonesia and its relation to antibiotic resistance. We determined the minimum inhibition concentration (MIC) of amoxicillin, clarithromycin, levofloxacin, metronidazole and tetracycline by the Etest to measure the planktonic susceptibility of 101 H. pylori strains. Biofilms were quantified by the crystal violet method. The minimum biofilm eradication concentration (MBEC) was obtained by measuring the survival of bacteria in a biofilm after exposure to antibiotics. The majority of the strains formed a biofilm (93.1% (94/101)), including weak (75.5%) and strong (24.5%) biofilm-formers. Planktonic resistant and sensitive strains produced relatively equal amounts of biofilms. The resistance proportion, shown by the MBEC measurement, was higher in the strong biofilm group for all antibiotics compared to the weak biofilm group, especially for clarithromycin (p = 0.002). Several cases showed sensitivity by the MIC measurement, but resistance according to the MBEC measurements (amoxicillin, 47.6%; tetracycline, 57.1%; clarithromycin, 19.0%; levofloxacin, 38.1%; and metronidazole 38.1%). Thus, biofilm formation may increase the survival of H. pylori and its resistance to antibiotics. Biofilm-related antibiotic resistance should be evaluated with antibiotic susceptibility.
  12. Kuo YT, Liou JM, El-Omar EM, Wu JY, Leow AHR, Goh KL, et al.
    Lancet Gastroenterol Hepatol, 2017 10;2(10):707-715.
    PMID: 28781119 DOI: 10.1016/S2468-1253(17)30219-4
    BACKGROUND: So far, a comprehensive systematic review and meta-analysis has not been done of the prevalence of primary antibiotic resistance in Helicobacter pylori in the Asia-Pacific region. We aimed to assess the trends and regional differences in primary antibiotic resistance to H pylori in the Asia-Pacific region and to examine the relation between resistance and first-line eradication.

    METHODS: We did a systematic review and meta-analysis of primary antibiotic resistance to H pylori and the efficacy of first-line regimens in the Asia-Pacific region. We searched PubMed, Embase, and the Cochrane Library for articles published between Jan 1, 1990, and Sept 30, 2016; we also searched abstracts from international conferences. Both observational studies and randomised controlled trials were eligible for inclusion in the analysis of primary antibiotic resistance, but only randomised controlled trials were eligible for inclusion in the analysis of efficacy of first-line therapies. Meta-analysis was by the random-effects model to account for the substantial variations in resistance across the region. We did subgroup analyses by country and study period (ie, before 2000, 2001-05, 2006-10, and 2011-15) to establish country-specific prevalences of primary antibiotic resistance and first-line eradication rates. This study is registered with PROSPERO, number CRD42017057905.

    FINDINGS: 176 articles from 24 countries were included in our analysis of antibiotic resistance. The overall mean prevalences of primary H pylori resistance were 17% (95% CI 15-18) for clarithromycin, 44% (95% CI 39-48) for metronidazole, 18% (95% CI 15-22) for levofloxacin, 3% (95% CI 2-5) for amoxicillin, and 4% (95% CI 2-5) for tetracycline. Prevalence of resistance to clarithromycin and levofloxacin rose significantly over time during the period investigated, whereas resistance to other antibiotics remained stable. 170 articles from 16 countries were included in analysis of efficacy of first-line therapies. We noted unsatisfactory efficacy (ie, <80%) with clarithromycin-containing regimens in countries where the clarithromycin resistance rates were higher than 20%.

    INTERPRETATION: The prevalence of primary antibiotic resistance varied greatly among countries in the Asia-Pacific region, and thus treatment strategy should be adapted relative to country-specific resistance patterns. Clarithromycin-containing regimens should be avoided in countries where the prevalence of clarithromycin resistance is higher than 20%.

    FUNDING: Ministry of Health and Welfare of Taiwan, Ministry of Science and Technology of Taiwan, and Amity University.

  13. Fauzia KA, Aftab H, Miftahussurur M, Waskito LA, Tuan VP, Alfaray RI, et al.
    BMC Microbiol, 2023 Jun 01;23(1):159.
    PMID: 37264297 DOI: 10.1186/s12866-023-02889-8
    BACKGROUND: Infection with Helicobacter pylori as the cause of gastric cancer is a global public health concern. In addition to protecting germs from antibiotics, biofilms reduce the efficacy of H. pylori eradication therapy. The nucleotide polymorphisms (SNPs) related with the biofilm forming phenotype of Helicobacter pylori were studied.

    RESULTS: Fifty-six H. pylori isolate from Bangladeshi patients were included in this cross-sectional study. Crystal violet assay was used to quantify biofilm amount, and the strains were classified into high- and low-biofilm formers As a result, strains were classified as 19.6% high- and 81.4% low-biofilm formers. These phenotypes were not related to specific clades in the phylogenetic analysis. The accessories genes associated with biofilm from whole-genome sequences were extracted and analysed, and SNPs among the previously reported biofilm-related genes were analysed. Biofilm formation was significantly associated with SNPs of alpA, alpB, cagE, cgt, csd4, csd5, futB, gluP, homD, and murF (P 

  14. Dewayani A, Afrida Fauzia K, Alfaray RI, Waskito LA, Doohan D, Rejeki PS, et al.
    PLoS One, 2023;18(5):e0284958.
    PMID: 37200323 DOI: 10.1371/journal.pone.0284958
    INTRODUCTION: Inadequate antimicrobial treatment has led to multidrug-resistant (MDR) bacteria, including Helicobacter pylori (H. pylori), which one of the notable pathogens in the stomach. Antibiotic-induced changes in the microbiota can negatively affect the host. This study aimed to determine the influence of H. pylori resistance on the diversity and abundance of the stomach microbiome.

    METHODS: Bacterial DNA was extracted from biopsy samples of patients presenting dyspepsia symptoms with H. pylori positive from cultures and histology. DNA was amplified from the V3-V4 regions of the 16S rRNA gene. In-vitro E-test was used to detect antibiotic resistance. Microbiome community analysis was conducted through α-diversity, β-diversity, and relative abundance.

    RESULTS: Sixty-nine H. pylori positive samples were eligible after quality filtering. Following resistance status to five antibiotics, samples were classified into 24 sensitive, 24 single resistance, 16 double resistance, 5 triple resistance. Samples were mostly resistant to metronidazole (73.33%; 33/45). Comparation of four groups displayed significantly elevated α-diversity parameters under the multidrug resistance condition (all P <0.05). A notable change was observed in triple-resistant compared to sensitive (P <0.05) and double-resistant (P <0.05) groups. Differences in β-diversity by UniFrac and Jaccard were not significant in terms of the resistance (P = 0.113 and P = 0.275, respectively). In the triple-resistant group, the relative abundance of Helicobacter genera was lower, whereas that of Streptococcus increased. Moreover, the linear discriminant analysis effect size (LEfSe) was associated with the presence of Corynebacterium and Saccharimonadales in the single-resistant group and Pseudomonas and Cloacibacterium in the triple-resistant group.

    CONCLUSION: Our results suggest that the resistant samples showed a higher trend of diversity and evenness than the sensitive samples. The abundance of H. pylori in the triple-resistant samples decreased with increasing cohabitation of pathogenic bacteria, which may support antimicrobial resistance. However, antibiotic susceptibility determined by the E-test may not completely represent the resistance status.

  15. Hong TC, El-Omar EM, Kuo YT, Wu JY, Chen MJ, Chen CC, et al.
    Lancet Gastroenterol Hepatol, 2024 Jan;9(1):56-67.
    PMID: 37972625 DOI: 10.1016/S2468-1253(23)00281-9
    BACKGROUND: We previously showed rising primary antibiotic resistance of Helicobacter pylori during 1990-2015 in the Asia-Pacific region. However, whether primary antibiotic resistance continues to rise is unknown. Therefore, we aimed to assess the latest prevalence of H pylori antibiotic resistance in this region.

    METHODS: We did an updated systematic review and meta-analysis of observational studies and randomised controlled trials published in PubMed, Embase, and Cochrane Library between Jan 1, 1990, and July 12, 2023. Studies investigating primary H pylori resistance to clarithromycin, metronidazole, levofloxacin, amoxicillin, or tetracycline in individuals naive to eradication therapy in the Asia-Pacific region (as defined by the UN geoscheme) were eligible for inclusion. There were no language restrictions. Studies that focused on specific subpopulations (eg, children) were excluded. Using a standardised extraction form, two authors independently reviewed and extracted summary data from all eligible articles. The updated prevalence of antibiotic resistance was generated by meta-analysis under a random-effects model and subgroup analyses were done by countries and periods of study. Between-study variability was assessed by use of I2. The study is registered in PROSPERO, CRD42022339956.

    FINDINGS: A total of 351 studies, including 175 new studies and 176 studies from our previous analysis, were included in this meta-analysis. The overall prevalence of primary antibiotic resistance of H pylori between 1990 and 2022 was 22% (95% CI 20-23; I2=96%) for clarithromycin, 52% (49-55; I2=99%) for metronidazole, 26% (24-29; I2=96%) for levofloxacin, 4% (3-5; I2=95%) for tetracycline, and 4% (3-5; I2=95%) for amoxicillin. Prevalence varied considerably between countries and across study periods. From 1990 to 2022, the prevalence of primary resistance increased for clarithromycin, metronidazole, and levofloxacin but remained stable for amoxicillin and tetracycline. The latest primary resistance prevalences were 30% (95% CI 28-33; I2=93%) for clarithromycin, 61% (55-66; I2=99%) for metronidazole, 35% (31-39; I2=95%) for levofloxacin, 4% (2-6; I2=96%) for tetracycline, and 6% (4-8; I2=96%) for amoxicillin in the Asia-Pacific region.

    INTERPRETATION: Treatment guidelines should be adapted in response to the rising primary resistance of key antibiotics for H pylori eradication. A global policy to control and monitor the antibiotic resistance of H pylori is urgently needed.

    FUNDING: Ministry of Health and Welfare of Taiwan, National Science and Technology Council of Taiwan, and National Taiwan University.

    TRANSLATION: For the Chinese translation of the abstract see Supplementary Materials section.

  16. Mahachai V, Vilaichone RK, Pittayanon R, Rojborwonwitaya J, Leelakusolvong S, Maneerattanaporn M, et al.
    J Gastroenterol Hepatol, 2018 Jan;33(1):37-56.
    PMID: 28762251 DOI: 10.1111/jgh.13911
    Helicobacter pylori (H. pylori) infection remains to be the major cause of important upper gastrointestinal diseases such as chronic gastritis, peptic ulcer, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. H. pylori management in ASEAN: the Bangkok consensus report gathered key opinion leaders for the region to review and evaluate clinical aspects of H. pylori infection and to develop consensus statements, rationales, and grades of recommendation for the management of H. pylori infection in clinical practice in ASEAN countries. This ASEAN Consensus consisted of 34 international experts from 10 ASEAN countries, Japan, Taiwan, and the United States. The meeting mainly focused on four issues: (i) epidemiology and disease association; (ii) diagnostic tests; (iii) management; and (iv) follow-up after eradication. The final results of each workshop were presented for consensus voting by all participants. Statements, rationale, and recommendations were developed from the available current evidence to help clinicians in the diagnosis and treatment of H. pylori and its clinical diseases.
  17. Liou JM, Malfertheiner P, Lee YC, Sheu BS, Sugano K, Cheng HC, et al.
    Gut, 2020 12;69(12):2093-2112.
    PMID: 33004546 DOI: 10.1136/gutjnl-2020-322368
    OBJECTIVE: A global consensus meeting was held to review current evidence and knowledge gaps and propose collaborative studies on population-wide screening and eradication of Helicobacter pylori for prevention of gastric cancer (GC).

    METHODS: 28 experts from 11 countries reviewed the evidence and modified the statements using the Delphi method, with consensus level predefined as ≥80% of agreement on each statement. The Grading of Recommendation Assessment, Development and Evaluation (GRADE) approach was followed.

    RESULTS: Consensus was reached in 26 statements. At an individual level, eradication of H. pylori reduces the risk of GC in asymptomatic subjects and is recommended unless there are competing considerations. In cohorts of vulnerable subjects (eg, first-degree relatives of patients with GC), a screen-and-treat strategy is also beneficial. H. pylori eradication in patients with early GC after curative endoscopic resection reduces the risk of metachronous cancer and calls for a re-examination on the hypothesis of 'the point of no return'. At the general population level, the strategy of screen-and-treat for H. pylori infection is most cost-effective in young adults in regions with a high incidence of GC and is recommended preferably before the development of atrophic gastritis and intestinal metaplasia. However, such a strategy may still be effective in people aged over 50, and may be integrated or included into national healthcare priorities, such as colorectal cancer screening programmes, to optimise the resources. Reliable locally effective regimens based on the principles of antibiotic stewardship are recommended. Subjects at higher risk of GC, such as those with advanced gastric atrophy or intestinal metaplasia, should receive surveillance endoscopy after eradication of H. pylori.

    CONCLUSION: Evidence supports the proposal that eradication therapy should be offered to all individuals infected with H. pylori. Vulnerable subjects should be tested, and treated if the test is positive. Mass screening and eradication of H. pylori should be considered in populations at higher risk of GC.

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