Primary resistance to antibiotics and its clinical impact on the efficacy of Helicobacter pylori lansoprazole-based triple therapies

Vonoprazan-based triple therapy is effective for Helicobacter pylori eradication irrespective of clarithromycin susceptibility

BACKGROUND

Helicobacter pylori causes peptic ulcers and accounts for over 90% of gastric cancers; however, eradication rates have been declining due to antimicrobial resistance. Vonoprazan (VPZ), a potassium-competitive acid blocker, produces rapid and profound gastric acid suppression and has shown promising effects in the improvement of H. pylori eradication rates. The efficacy and safety of VPZ-based triple therapy as a first-line regimen for H. pylori eradication and its relationship with clarithromycin (CAM) susceptibility were evaluated.

METHODS

From May 2015 to September 2017, H. pylori-infected patients who underwent esophagogastroduodenoscopy with CAM susceptibility testing were prospectively enrolled. Patients received a 7-day triple therapy regimen (VAC) of VPZ (20 mg), amoxicillin (750 mg), and CAM (200 mg) twice daily. Eradication rates, demographics, CAM susceptibility, and safety profiles were assessed.

RESULTS

VAC was administered to 146 patients (median age: 63, range: 22-85 years) (60% of whom were females) who underwent CAM susceptibility testing, and 131 patients underwent ¹³C-urea breath testing to evaluate eradication success. The prevalence of CAM resistance was 34.2%. The overall eradication rates of VAC in per protocol (PP) and "intention to treat" (ITT) analyses were 90.8% (n = 131) and 81.5% (n = 146), respectively. In PP analysis for CAM susceptibility, the eradication rates of VAC were comparable between CAM-sensitive (91.6%, n = 83) and CAM-resistant (89.4%, n = 47) strains. The corresponding rates from the ITT analysis were 80.0% (n = 95) and 84.0% (n = 50), respectively. No adverse events requiring discontinuation of VAC were observed.

CONCLUSIONS

CAM-resistant H. pylori was prevalent in one-third of patients in the Tokyo metropolitan area. VPZ-based triple therapy was highly effective and well-tolerated irrespective of CAM susceptibility. Therefore, it could be a valuable first-line treatment regimen for H. pylori infection.

Increase in antibiotic resistant Helicobacter pylori in a University Hospital in Japan

Background

Eradication effectively prevents Helicobacter pylori-associated diseases; however, H. pylori antibiotic resistance has increased throughout Japan and worldwide. This study aimed to assess rates of resistance to antibiotics; amoxicillin, clarithromycin and metronidazole in a University Hospital in Japan.

Materials and methods

H. pylori (208 strains) were isolated from patients at the Okayama University Hospital in Japan. The minimum inhibitory concentrations (MIC) were determined using the mean values of the E-test to determine the antimicrobial susceptibilities of the strains. Sequencing and gene analysis were performed to analyze resistance genes to clarithromycin and amoxicillin.

Results

Rates of amoxicillin, clarithromycin, and metronidazole resistance were 13%, 48%, and 49%, respectively. Genetic analysis indicated that the A2143G point mutation in 23S rDNA is closely associated with the MIC of clarithromycin. The MIC in amoxicillin-resistant strains increased with an increase in the number of PBP1A amino acids mutations.

Conclusion

Genetic analysis for resistant strains is not clinically effective in cases of amoxicillin resistance. Numerous bacteria with already high antibiotic resistance rates have been isolated in large hospitals such as a University Hospital. For effective eradication therapy, MIC measurement should be considered via several methods.

Baicalin, Baicalein, and Lactobacillus Rhamnosus JB3 Alleviated Helicobacter pylori Infections in Vitro and in Vivo

Helicobacter pylori infection is associated with chronic gastritis, peptic ulcers, and gastric cancer. The flavonoid compounds baicalin and baicalein found in many medicinal plants exhibit an anti-inflammatory effect. The administration of Lactobacillus strains reducing the risk of H. pylori infection is well accepted. In this study, the therapeutic effects against H. pylori infection of baicalin, baicalein, and L. rhamnosus JB3 (LR-JB3), isolated from a dairy product, were investigated. Compared to baicalin, baicalein exhibited stronger anti-H. pylori activity and cytotoxicity on human gastric cancer epithelial AGS cells. Baicalin and baicalein both suppressed the vacA gene expression of H. pylori and interfered with the adhesion and invasion ability of H. pylori to AGS cells, as well as decreased H. pylori-induced interleukin (IL)-8 expression. In the mice infection model, high dosages of baicalin and baicalein inhibited H. pylori growth in the mice stomachs. Serum IL-1β levels and H. pylori-specific serum IgM and IgA levels in mice treated with baicalin and baicalein were decreased. Moreover, a synergistic therapeutic effect of baicalein and LR-JB3 on eradicating H. pylori infections was observed. Thus, administrating baicalin, baicalein, or LR-JB3 for an H. pylori infection could offer similar therapeutic effects to administering antibiotics while not disturbing the balance of gut microbiota. This study revealed the effects of baicalin, baicalein, and LR-JB3 on attenuating the virulence of H. pylori. The synergistic effect with baicalein and LR-JB3 provides the experimental rationale for testing the reliability, safety, and efficacy of this approach in higher animals and perhaps ultimately in humans to eradicate H. pylori infections. PRACTICAL APPLICATION: Baicalin and baicalein exert health promotion and avoidance of H. pylori infections by interfering with H. pylori growth and virulence. Lactobacillus rhamnosus JB3 was used to reduce the gastric inflammation caused by H. pylori infection.

Eudesmin attenuates Helicobacter pylori-induced epithelial autophagy and apoptosis and leads to eradication of H. pylori infection

Eudesmin has been proven to possess anti-inflammatory effects. In the present study, the effects of eudesmin on Helicobacter pylori (H. pylori)-mediated autophagy, apoptosis, immune response and inflammation were determined in human gastric adenocarcinoma (AGS) cells in vitro and in C57BL/6 mice in vivo. Detection of the production of interleukin (IL)-8, IL-1β and immunoglobulin M (IgM) was performed using ELISA. Identification of the activation of apoptosis-associated caspase-3, -8 and -9 proteins, Bcl-2-associated X protein (Bax) and BH3 interacting domain death agonist (Bid) protein, was determined through western blot analysis. Autophagy microtubule-associated protein 1A/1B-light chain 3, isoform B (LC-3B) expression was measured using immunostaining. The results of the present study demonstrated that eudesmin inhibited the growth of H. pylori, with increased inhibition activity against antibiotic resistant strains compared with the reference strain. In addition, H. pylori-induced IL-8 secretion, LC-3B expression and apoptosis-associated protein (caspase-3, -8 and -9, Bax and Bid) activation in AGS cells was suppressed by eudesmin. Furthermore, eudesmin suppressed IL-1β and IgM production in H. pylori-infected C57BL/6 mice in vivo. In conclusion, eudesmin may be developed as a promising therapeutic agent to prevent and/or treat H. pylori-associated gastric inflammation.

Mixed Infections of Helicobacter pylori Isolated from Patients with Gastrointestinal Diseases in Taiwan

Background. Persistent Helicobacter pylori infection may induce several upper gastrointestinal diseases. Two major virulence factors of H. pylori, vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA), are thought to be associated with the severity of disease progression. The distribution of vacA and cag-pathogenicity island (cag-PAI) alleles varies in H. pylori isolated from patients in different geographic regions. Aim. To assess the association between mixed infection of H. pylori clinical isolates from Taiwanese patients and the severity of gastrointestinal diseases. Methods. A total of 70 patients were enrolled in this study. Six distinct and well-separated colonies were isolated from each patient and 420 colonies were analyzed to determine the genotypes of virulence genes. Results. The prevalence of mixed infections of all H. pylori-infected patients was 28.6% (20/70). The rate of mixed infections in patients with duodenal ulcer (47.6%) was much higher than that with other gastrointestinal diseases (P < 0.05). Conclusions. H. pylori mixed infections show high genetic diversity that may enhance bacterial adaptation to the hostile environment of the stomach and contribute to disease development.

Seven-Day Nonbismuth Containing Quadruple Therapy Could Achieve a Grade “A” Success Rate for First-Line Helicobacter pylori Eradication. Biomed Res Int. 2015;2015:623732. [PMID: 26090428 PMCID: PMC4452293 DOI: 10.1155/2015/623732]

This prospective study was to assess the efficacy of nonbismuth containing quadruple therapy as first-line H. pylori treatment and to determine the clinical factors influencing patient outcome. We enrolled 200 H. pylori-infected naïve patients. They were prescribed either a 7-day nonbismuth containing quadruple therapy group (EACM, esomeprazole 40 mg twice daily, amoxicillin 1 g twice daily, metronidazole 500 mg twice daily, and clarithromycin 500 mg twice daily) or a 7-day standard triple therapy group (EAC, esomeprazole 40 mg twice daily, amoxicillin 1 g twice daily, and clarithromycin 500 mg twice daily). Follow-up studies to assess treatment responses were carried out 8 weeks later. The eradication rates attained by EACM and EAC groups were 95.6% (95% confidence interval [CI] = 89.4%–98.3%) and 79.3% (95% CI = 70%–86.4%) in the per-protocol analysis (P < 0.001) and 88% (95% CI = 80.2%–93.0%) and 73% (95% I = 63.6%–80.3%) in the intention-to-treat analysis (P = 0.007). Clarithromycin resistance, metronidazole resistance, and dual clarithromycin and metronidazole resistances were the clinical factors influencing H. pylori eradication in EACM group. Clarithromycin resistance and dual clarithromycin and metronidazole resistances were the influential factor for EAC treatment. In conclusion, the results suggest that 7-day nonbismuth containing quadruple therapy could achieve a grade “A” report card for first-line H. pylori treatment.

The Primary Resistance of Helicobacter pylori in Taiwan after the National Policy to Restrict Antibiotic Consumption and Its Relation to Virulence Factors-A Nationwide Study

Objective

The Taiwan Government issued a policy to restrict antimicrobial usage since 2001. We aimed to assess the changes in the antibiotic consumption and the primary resistance of H. pylori after this policy and the impact of virulence factors on resistance.

Methods

The defined daily dose (DDD) of antibiotics was analyzed using the Taiwan National Health Insurance (NHI) research database. H. pylori strains isolated from treatment naïve (N=1395) and failure from prior eradication therapies (N=360) from 9 hospitals between 2000 and 2012 were used for analysis. The minimum inhibitory concentration was determined by agar dilution test. Genotyping for CagA and VacA was determined by PCR method.

Results

The DDD per 1000 persons per day of macrolides reduced from 1.12 in 1997 to 0.19 in 2008, whereas that of fluoroquinolones increased from 0.12 in 1997 to 0.35 in 2008. The primary resistance of amoxicillin, clarithromycin, metronidazole, and tetracycline remained as low as 2.2%, 7.9%, 23.7%, and 1.9% respectively. However, the primary levofloxacin resistance rose from 4.9% in 2000–2007 to 8.3% in 2008–2010 and 13.4% in 2011–2012 (p=0.001). The primary resistance of metronidazole was higher in females than males (33.1% vs. 18.8%, p<0.001), which was probably attributed to the higher consumption of nitroimidazole. Neither CagA nor VacA was associated with antibiotic resistance.

Conclusions

The low primary clarithromycin and metronidazole resistance of H. pylori in Taiwan might be attributed to the reduced consumption of macrolides and nitroimidazole after the national policy to restrict antimicrobial usage. Yet, further strategies are needed to restrict the consumption of fluoroquinolones in the face of rising levofloxacin resistance.

Lactobacillus pentosus strain LPS16 produces lactic acid, inhibiting multidrug-resistant Helicobacter pylori

BACKGROUND/PURPOSE

Helicobacter pylori is a human gastric pathogen. Antibiotic resistance of H. pylori has become a problem increasing the failure of H. pylori eradication. Therefore alternative approaches are required. The aim of this study was to evaluate the anti-H. pylori activity of Lactobacillus pentosus strain LPS16 and the mechanism of its killing effect.

METHODS

The anti-H. pylori activity of LPS16 was determined by the disc diffusion test and time killing assay. High-performance liquid chromatography analysis was used to analyze the secreted compounds of LPS16. Sixty H. pylori strains isolated from different gastric diseases, having different antibiotic susceptibility were collected to analyze the spectrum of anti-H. pylori activity of LPS16. Adhesion ability of LPS16 to gastric epithelial cell lines was assayed by flow cytometry.

RESULTS

The anti-H. pylori activity of LPS16 depended on the secreted component, and lactic acid mediated bactericidal activity against H. pylori. The bactericidal activity did not vary significantly among the strains isolated from different diseases having different antibiotic susceptibility. Moreover, LPS16 can adhere on gastric epithelial cell lines AKG and MKN45.

CONCLUSION

L. pentosus strain LPS16 had the broad-spectrum anti-H. pylori activity, suggesting that it can be used to prevent H. pylori infection.

Substitutions in penicillin-binding protein 1 in amoxicillin-resistant Helicobacter pylori strains isolated from Korean patients

Background/Aims

A worldwide increase in amoxicillin resistance in Helicobacter pylori is having an adverse effect on eradication therapy. In this study, we investigated the mechanism of the amoxicillin resistance of H. pylori in terms of amino acid substitutions in penicillin-binding protein 1 (PBP1).

Methods

In total, 150 H. pylori strains were isolated from 144 patients with chronic gastritis, peptic ulcers, or stomach cancer. The minimum inhibitory concentrations (MICs) of the strains were determined with a serial 2-fold agar dilution method. The resistance breakpoint for amoxicillin was defined as >0.5 µg/mL.

Results

Nine of 150 H. pylori strains showed amoxicillin resistance (6%). The MIC values of the resistant strains ranged from 1 to 4 µg/mL. A PBP1 sequence analysis of the resistant strains revealed multiple amino acid substitutions: Val16→Ile, Val45→Ile, Ser414→Arg, Asn562→Tyr, Thr593→Ala, Gly595→Ser, and Ala599→Thr. The natural transformation of these mutated genes into amoxicillin-sensitive strains was performed in two separate pbp1 gene segments. A moderate increase in the amoxicillin MIC was observed in the segment that contained the penicillin-binding motif of the C-terminal portion, the transpeptidase domain.

Conclusions

pbp1 mutation affects the amoxicillin resistance of H. pylori through the transfer of the penicillin-binding motif.

Comparison of the once-daily levofloxacin-containing triple therapy with the twice-daily standard triple therapy for first-line Helicobacter pylori eradication: a prospective randomised study

BACKGROUND/AIMS

Simple compound of Helicobacter pylori eradication therapy may improve drug compliance of patients. The aims of this study were to compare the efficacy and tolerability of a simple combination containing levofloxacin 7-day once-daily with standard twice-daily triple therapy.

PATIENTS AND METHODS

This was a prospective, randomised, open-label trial. A total of 189 consecutive patients diagnosed with peptic ulcer and H. pylori infection were enrolled. Patients were randomly divided into two groups: LEC group--levofloxacin 500 mg, esomeprazole 40 mg and clarithromycin 500 mg once daily for 7 days; AEC group--amoxicillin 1 g, esomeprazole 40 mg and clarithromycin 500 mg twice daily for 7 days.

RESULTS

There were 90 patients in the LEC group and 99 patients in the AEC group. By intention-to-treat and per-protocol analysis, the H. pylori eradication rate was 78.9% [71/90; 95% confidence interval (CI), 70.3-87.5%] and 83.5% (71/85; 95% CI, 75.5-91.6%) respectively, in the LEC group; and 74.8% (74/99; 95% CI, 66.0-83.5%) and 86.0% (74/86; 95% CI, 78.6-93.5%) respectively, in the AEC group. The incidence and tolerability of side effects were similar between these two groups.

CONCLUSION

The efficacy and tolerability of once-daily levofloxacin-containing triple therapy are equal to those of the standard twice-daily triple therapy in this study. However, none of the treatment regimens evaluated achieved enough eradication efficacies to be considered as a recommendable first-line treatment.

Change in antibiotic resistance of Helicobacter pylori strains and the effect of A2143G point mutation of 23S rRNA on the eradication of H. pylori in a single center of Korea

BACKGROUND

The current prevalence of primary antibiotic resistance of H. pylori is not known in Korea. This study was done to evaluate the prevalence of primary antibiotic resistance of H. pylori, and to evaluate the effect of point mutations of 23S rRNA on the rate of eradication of H. pylori.

METHODS

H. pylori were isolated from gastric mucosal biopsy specimens obtained from 222 Koreans. The susceptibilities of the H. pylori isolates to amoxicillin, clarithromycin, metronidazole, tetracycline, ciprofloxacin, and levofloxacin were examined using the agar dilution method. DNA sequencing was carried out to detect H. pylori 23S rRNA mutations.

RESULTS

The resistance to clarithromycin, tetracycline, ciprofloxacin, and levofloxacin increased during the period of 2007 to 2009 compared with 2003 to 2005 (P<0.05). However, amoxicillin and metronidazole resistance slightly decreased. The rates of eradication were 95.5% for the clarithromycin-sensitive strains, which was higher than the 67.9% for the clarithromycin-resistant strains (P=0.001). By contrast, the eradication rate was 100% in patients with amoxicillin-resistant H. pylori. Among 26 clarithromyin-resistant strains, 6 (23%) had A2143G mutations, and all of the cases in which these mutations were present were not eradicated by proton pump inhibitor-based triple therapy (P=0.0004). By contrast, none of the 26 clarithromyin-sensitive strains had A2143G mutations. The T2183C and A2223G mutations were frequently found in the sensitive strains and in the resistant strains.

CONCLUSIONS

Clarithromycin resistance of H. pylori, which determined the efficacy of H. pylori eradication of proton pump inhibitor triple regimen, was found to be increased in a single center study. A2143G was an important 23S rRNA mutation associated with clarithromycin resistance and affected the H. pylori eradication efficacy.

Interleukin-1beta and -10 polymorphisms influence erosive reflux esophagitis and gastritis in Taiwanese patients

BACKGROUND AND AIMS

Helicobacter pylori (H. pylori) infection induces cytokine production and is associated with gastrointestinal diseases. This study examined the relationship of gene polymorphisms, including interleukin (IL)-1beta, -10, -8, and tumor necrosis factor-alpha (TNF-alpha), H. pylori infection, and susceptibility to gastrointestinal disorders in Taiwanese patients.

METHODS

IL-1beta-511/-31/+3953, -10-1082/-819/-592, -8-251, and TNF-alpha-308 polymorphisms were assessed in 628 gastrointestinal disease patients, and 176 healthy controls were analyzed using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

IL-1beta-511 T/T and -31 C/C genotypes, and IL-1beta-511 T and -31 C alleles were associated with an increased risk of reflux esophagitis (P = 0.034, odds ratio [OR] = 1.384, 95% confidence interval [CI]: 1.023-1.871; P = 0.031, OR = 1.388, 95% CI: 1.028-1.873; P = 0.044, OR = 1.342, 95% CI: 1.008-1.786; and P = 0.040, OR = 1.349, 95% CI: 1.014-1.796, respectively). No relationship was found between H. pylori infection and the risk of reflux esophagitis. IL-10-819 C/T and -10-592 A/C genotypes and IL-10-1082/-819/-592 ATA/ACC and ATA/GCC haplotypes were associated with an increased risk of gastritis (P = 0.021, OR = 1.721, 95% CI: 1.084-2.733; P = 0.016, OR = 1.766, 95% CI: 1.112-2.805; P = 0.039, OR = 1.662, 95% CI: 1.024-2.697; and P = 0.035, OR = 1.600, 95% CI: 1.024-2.499, respectively).

CONCLUSION

Among Taiwanese patients, IL-1beta and -10 polymorphisms were associated with an increased risk of erosive reflux esophagitis and gastritis, respectively.

Changes in 12-Year First-Line Eradication Rate of Helicobacter pylori Based on Triple Therapy with Proton Pump Inhibitor, Amoxicillin and Clarithromycin

A triple therapy based on a proton pump inhibitor (PPI), amoxicillin (AMPC), and clarithromycin (CAM) is recommended as a first-line therapy for Helicobacter pylori (H. pylori) eradication and is widely used in Japan. However, a decline in eradication rate associated with an increase in prevalence of CAM resistance is viewed as a problem. We investigated CAM resistance and eradication rates over time retrospectively in 750 patients who had undergone the triple therapy as first-line eradication therapy at Nagoya City University Hospital from 1995 to 2008, divided into four terms (Term 1: 1997-2000, Term 2: 2001-2003, Term 3: 2004-2006, Term 4: 2007-2008). Primary resistance to CAM rose significantly over time from 8.7% to 23.5%, 26.7% and 34.5% while the eradication rate decreased significantly from 90.6% to 80.2%, 76.0% and 74.8%. Based on the PPI type, significant declines in eradication rates were observed with omeprazole or lansoprazole, but not with rabeprazole. A decrease in the H. pylori eradication rate after triple therapy using a PPI + AMPC + CAM has been acknowledged, and an increase in CAM resistance is considered to be a factor. From now on, a first-line eradication regimen that results in a higher eradication rate ought to be investigated.

Prevalence of antimicrobial resistance in Helicobacter pylori isolates in Taiwan in relation to consumption of antimicrobial agents

During 1998-2004, a total of 218 Helicobacter pylori isolates were obtained from patients who were randomised to receive one of the following regimens in a medical centre in Taiwan: lansoprazole, amoxicillin and clarithromycin (LAC) therapy; or lansoprazole, metronidazole and clarithromycin (LMC) therapy. In the LMC group, resistance rates for metronidazole and clarithromycin reduced from 48.6% (1998-2000) to 20.4% (2001-2004) (P<0.05) and from 13.5% to 6.3% (P<0.05), respectively. Analysis of annual antimicrobial consumption found that metronidazole use was slowly decreased both in the total population and in gastrointestinal disease patients. The per-protocol analysis revealed a higher eradication rate for patients using LMC therapy in 2001-2004 (82.6% vs. 75.0%), whilst there was similar efficacy for LAC therapy (84.8% vs. 84.2%). This observation suggests an effective programme to control H. pylori antibiotic resistance and hence elevate its cure rate.

Prevalence of primary fluoroquinolone resistance among clinical isolates of Helicobacter pylori at a University Hospital in Southern Taiwan

BACKGROUND

Fluoroquinolone-containing therapy is effective in eradicating Helicobacter pylori. However, the resistance rate of H. pylori to fluoroquinolones in Taiwan has not yet been reported. In this study, we aimed to investigate the susceptibility to antibiotics commonly used in eradication schedules and fluoroquinolones in H. pylori.

METHODS

A total of 210 clinical isolates of H. pylori were collected from April 1998 to September 2007 from patients in southern Taiwan. The in vitro activities of six antimicrobial agents were determined by the agar dilution method and Etest. The mutations in quinolone resistance-determining regions of gyrA and gyrB were investigated by direct sequencing.

RESULTS

Overall, 5.7% of the isolates were resistant to ciprofloxacin and levofloxacin. The resistance rate to amoxicillin, clarithromycin, metronidazole, and tetracycline was 1.0% (two of 210), 9.5% (20 of 210), 27.6% (58 of 210), and 0.5% (one of 210), respectively. The resistance rate to either ciprofloxacin or to levofloxacin increased from 2.8% (1998-2003) to 11.8% (2004-2007). The mutations in gyrA at N87 or D91 had an impact on primary fluoroquinolone resistance in H. pylori. Garenoxacin, but not moxifloxacin, had a good in vitro inhibitory effect against ciprofloxacin/levofloxacin-resistant strains compared with objective minimal inhibitory concentration values.

CONCLUSIONS

Drug resistance to ciprofloxacin and levofloxacin in H. pylori collected from 2004 to 2007 increased significantly compared with resistance level observed during 1998-2003. The continuous surveillance of quinolone resistance among H. pylori is important in this area.

Tailored eradication therapy based on fecal Helicobacter pylori clarithromycin sensitivities

BACKGROUND AND AIM

Helicobacter pylori (H. pylori) eradication rates using the PPI/AC regimen (proton pump inhibitor + amoxicillin + clarithromycin) are declining. We trialed tailoring eradication regimens according to clarithromycin (CAM) susceptibility.

METHODS

The subjects were 70 H. pylori positive adults. They were randomly allocated to a tailored group and a control group. In the tailored group, subjects with CAM-sensitive strains were given PPI/AC eradication therapy, and those with CAM-resistant strains were given PPI/AM (metronidazole instead of clarithromycin) therapy. The control group were all given PPI/AC therapy. CAM sensitivity was measured by collecting fecal specimens, and extracting the DNA. The 23S rRNA domain, associated with CAM susceptibility in H. pylori, was amplified using a nested polymerase chain reaction (PCR), and DNA sequencing was used to detect point mutations at A2143G and A2144G.

RESULTS

Eradication rates were 94.3% in the tailored group and 71.4% in the control group. In particular, the eradication rate was 100% for CAM-resistant strains in the tailored group.

CONCLUSIONS

In Japan, where CAM-resistant H. pylori strains are expected to continue to increase, tailored eradication therapy according to CAM sensitivity will be of benefit.

Helicobacter pylori isolates recovered from gastric biopsies of patients with gastro-duodenal pathologies in Cameroon: current status of antibiogram

OBJECTIVE

To determine the prevalence of Helicobacter pylori in patients with gastro-duodenal pathologies and the susceptibility patterns of isolates to the currently recommended antibiotic treatment regimen used in Cameroon.

METHODS

Consecutive dyspeptic patients referred to Douala General Hospital, Cameroon for endoscopy were recruited in the study. Gastric biopsies were collected from the patients and H. pylori isolated and identified following standard microbiology and biochemical techniques. Antibiotic susceptibility was determined by disk diffusion and agar dilution methods against clarithromycin, tetracycline, amoxicillin and metronidazole. Data were analysed using chi-square test and significance considered at P < 0.05.

RESULTS

Seventy-one (92.2%) of the 77 patients (mean age 44.5 +/- 15.7, range 15-77 years) were positive for H. pylori. The antibiotic susceptibility rates were 56% for tetracycline, 55.3% for clarithromycin, 14.4% for amoxicillin and 6.8% for metronidazole. The prevalence of clarithromycin resistance in males vs. females was 42.1%vs. 46.7%, while for metronidazole it was 89.5%vs. 94.7% (P > 0.05). Antimicrobial susceptibility results also revealed 12 antibiotypes based on resistance to the antimicrobial agents investigated. The resistance pattern, amoxicillin and metronidazole (AMR(R) MET(R)) was the most common (23.7%) amongst the isolates. More than 60% of the isolates exhibited multi-drug resistance to three or four antibiotics.

CONCLUSION

Multi-drug resistance is common against the current treatment regimen in Cameroon and, therefore, calls for urgent studies involving newer and broad spectrum antibiotics to address the problem.

Detection of the drug-resistant gene of Helicobacter pylori

Antibiotic-resistant Helicobacter pylori (H. pylori) and the resistance rate are increased due to the wide use of antibiotics. At present, the detection of antibiotic-resistant H. pylori is focused on the clarithromycin and metronidazole resistance testing using PCR-based molecular biology techniques. However, PCR-restriction fragment length polymorphism and real-time PCR in combination with melting curve analysis techniques have a broad prospect in detecting drug-resistant clarithromycin. They can detect it from tissue biopsy and stool samples, and thus can be used in detecting the resistance of a wide range of antibiotics. Western blot and PCR- restriction fragment length polymorphism can also detect the resistance of metronidazole, and can therefore develop into the routine procedures for detecting drug-resistant H. pylori.

Correlation between substitutions in penicillin-binding protein 1 and amoxicillin resistance in Helicobacter pylori

The correlation between the substitutions of penicillin-binding protein 1 (PBP1) and amoxicillin resistance was studied for the determination of the substitutions in PBP1 which confer amoxicillin resistance in Helicobacter pylori. By the comparison of the amino acid sequences of PBP1 in the amoxicillinresistant (n=3), low-susceptible (n=3), and susceptible (n=13) H. pylori isolates, the substitution Asn562-->Tyr, which is adjacent to KTG motif (555-557), was common and specific to amoxicillin-resistant H. pylori. Additionally, all amoxicillin-resistant isolates had multiple substitutions such as Ser414-->Arg in the transpeptidase region of PBP1 of H. pylori. Furthermore all transformants obtained by the natural transformation using the pbp1 genes of amoxicillin-resistant H. pylori isolates had multiple substitutions including Asn562-->Tyr. These results suggest that multiple amino acid substitutions in the transpeptidase region of PBP1 are closely related to amoxicillin resistance in H. pylori.

Efficacy and safety of faropenem in eradication therapy of Helicobacter pylori

AIMS

While triple therapy with a proton pump inhibitor, amoxicillin, and clarithromycin is the standard therapy for Helicobacter pylori eradication, it is ineffective against clarithromycin-resistant strains. To seek a better regimen for eradication therapy, we assessed the sensitivity of clinical strains seen in Japan to faropenem and then evaluated the efficacy and safety of eradication therapy containing this antibiotic.

METHODS

Minimum inhibitory concentrations (MICs) of faropenem were determined in 78 Japanese clinical H. pylori isolates using the agar dilution method. H. pylori-positive patients were consecutively assigned to a 7-day eradication therapy protocol with LAF (lansoprazole 60 mg/day, amoxicillin 2000 mg/day, and faropenem 600 mg/day), and then to a 14-day protocol. The outcomes of the therapies were assessed by (13)C-urea breath tests.

RESULTS

All 78 strains showed MICs of faropenem that were equal to or less than 0.2 microg/mL. The eradication rates according to intention-to-treat analyses were 46.5% with the 7-day therapy (n = 43) and 62.5% with the 14-day therapy (n = 32). No special measures were required to treat the adverse events observed in approximately one-third of the patients.

CONCLUSIONS

Faropenem was found to have good antimicrobial action against H. pylori in vitro. The 14-day LAF therapy successfully eradicated H. pylori in about two-thirds of the patients although the incidence of adverse events was high.

Gene expression profiling in human gastric mucosa infected with Helicobacter pylori

Pathogenic mechanisms associated with Helicobacter pylori infection enhance susceptibility of the gastric epithelium to carcinogenic conversion. We have characterized the gene expression profiles of gastric biopsies from 69 French Caucasian patients, of which 43 (62%) were infected with H. pylori. The bacterium was detected in 27 of the 42 antral biopsies examined and in 16 of the 27 fundic biopsies. Infected biopsies were selected for the presence of chronic active gastritis, in absence of metaplasia and dysplasia of the gastric mucosa. Infected antral and fundic biopsies exhibited distinct transcriptional responses. Altered responses were linked with: (1) the extent of polymorphonuclear leukocyte infiltration, (2) bacterial density, and (3) the presence of the virulence factors vacA, babA2, and cagA. Robust modulation of transcripts associated with Toll-like receptors, signal transduction, the immune response, apoptosis, and the cell cycle was consistent with expected responses to Gram-negative bacterial infection. Altered expression of interferon-regulated genes (IFITM1, IRF4, STAT6), indicative of major histocompatibility complex (MHC) II-mediated and Th1-specific responses, as well as altered expression of GATA6, have previously been described in precancerous states. Upregulation of genes abundantly expressed in cancer tissues (UBD, CXCL13, LY96, MAPK8, MMP7, RANKL, CCL18) or in stem cells (IFITM1 and WFDC2) may reveal a molecular switch towards a premalignant state in infected tissues. Tissue microarray analysis of a large number of biopsies, which were either positive or negative for the cag-A virulence factor, when compared to each other and to noninfected controls, confirmed observed gene alterations at the protein level, for eight key transcripts. This study provides 'proof-of-principle' data for identifying molecular mechanisms driving H. pylori-associated carcinogenesis before morphological evidence of changes along the neoplastic progression pathway.

High Helicobacter pylori resistance rate to clarithromycin in Turkey

GOALS

To assess the resistance of Helicobacter pylori to clarithromycin in Turkey.

BACKGROUND

Recent studies have emphasized the remarkable reduction in H. pylori eradication rates. Resistance to clarithromycin is the most important factor affecting the success of H. pylori eradication therapies.

STUDY

The study involved 110 consecutive adult dyspeptic patients infected with H. pylori. Resistance to clarithromycin was studied by real-time polymerase chain reaction method on gastric biopsy specimens.

RESULTS

Of the 110 patients, 56 (50.9%) were male and mean age (+/-SD) was 45.1+/-13.1 years. Overall, 53 (48.2%) patients were found to be resistant to clarithromycin. Resistance to clarithromycin was not statistically associated with age, sex, previous macrolide use, residence (urban/rural), education status, and presence of peptic ulcer.

CONCLUSIONS

The rate of resistance to clarithromycin was found to be markedly high. This result may explain the recently reported low success rates of H. pylori eradication therapies with clarithromycin.

Meta-analysis: the effect of antibiotic resistance status on the efficacy of triple and quadruple first-line therapies for Helicobacter pylori

BACKGROUND

Information regarding the effects of drug resistance on therapies for Helicobacter pylori is limited.

AIMS

To determine the effect of drug resistance on the efficacy of first-line treatment regimens for H. pylori and identify the most efficacious treatments in the presence of drug resistance.

METHODS

We searched for studies using the keywords: 'Helicobacter pylori','resistance' and 'treatment' or 'therapy'. Multilevel meta-regression models were used to determine the effect of drug resistance on treatment efficacy.

RESULTS

We analysed data from 93 studies with 10,178 participants. For triple therapies, clarithromycin resistance had a greater effect on treatment efficacy than nitroimidazole resistance. Metronidazole resistance reduced efficacy by 26% in triple therapies containing a nitroimidazole, tetracycline and bismuth, while efficacy was reduced by only 14% when a gastric acid inhibitor was added to the regimen. Quadruple therapies containing both clarithromycin and metronidazole were the most efficacious; >80% of H. pylori infections were consistently eradicated with these regimens.

CONCLUSIONS

Drug resistance was a strong predictor of efficacy across triple therapies for the eradication of H. pylori in adults. Resistance to either clarithromycin or metronidazole, but not both simultaneously, may be overcome by using quadruple therapies, especially those containing both clarithromycin and metronidazole.

A report card to grade Helicobacter pylori therapy

Helicobacter pylori causes a serious bacterial infectious disease, and the expectations of therapy should reflect this fact. Increasing antibiotic resistance, especially to clarithromycin, has significantly undermined the effectiveness of legacy triple therapy consisting of a proton pump inhibitor, clarithromycin, and amoxicillin. Current cure rates are consistently below 80% intention-to-treat, the accepted threshold separating acceptable from unacceptable treatment results. Grading clinical studies into effectiveness categories using prespecified criteria would allow clinicians to objectively identify and compare regimens. We offer a therapy report card similar to that used to grade the performance of school children. The intention-to-treat cure rate categories are: F or unacceptable ( 80%), D or poor (81-84%), C or fair (85-89%), B or good (90-95%), and A or excellent (95-100%). The category of "excellent" is based on the cure rates expected with other prevalent bacterial infectious diseases. We propose that only therapies that score "excellent" (grade = A) should be prescribed. Regimens scoring as B or "good" can be used if "excellent" results are not obtainable. In most regions legacy triple therapy should be abandoned as unacceptable. Quadruple therapy and sequential therapy are reasonable alternatives for initial therapy.

Quantifying gastric Helicobacter pylori infection: a comparison of quantitative culture, urease breath testing, and histology

Although there are several methods to detect Helicobacter pylori infection, there is no simple validated test to quantify the density of infection, which is believed to play a major role in the pathogenesis of H. pylori-associated gastritis and peptic ulceration. The aim of this study was to evaluate and compare noninvasive and invasive tests for assessing the level of H. pylori infection so as to facilitate the development and clinical testing of new antibiotic treatments. Healthy volunteers (n=323) were screened for H. pylori infection by serology and, if positive (n=86), invited to undergo (13)C urea breath testing (UBT) (n=55). An increase of >2.4 parts per thousand (13)CO(2) at 15 min compared to baseline was considered a positive test. Total cumulative urease activity (mumol) at 60 min was also calculated. UBT-positive subjects underwent endoscopy and nine biopsies were obtained from defined sites for quantitative culture and histological grading using the modified Sydney System. A total of 19 subjects were studied, 4 of whom underwent repeat testing. All subjects were positive for H. pylori by serology, UBT, culture, and histology. The increase in (13)CO(2) at 30 min correlated with the total cumulative urease activity at 60 min (r (2)=0.92, P< 0.0001). Bacterial counts (log cfu/biopsy; mean+/-SD) were 3.9+/-0.5, 3.9+/-0.4, and 3.9+/-0.6 at the lesser curve antrum, greater curve antrum, and corpus, respectively. There was no significant correlation between UBT results and bacterial counts at any biopsy site. Nor was there any significant correlation between the histology grading and either the UBT or the bacterial counts at any site. This study indicates that there is little correlation among the three methods used to measure bacterial burden in H. pylori infection. Thus, decrements in bacterial numbers during single-agent therapy cannot be measured reliably by UBT and therefore cannot be used to evaluate the potential efficacy of novel agents to treat gastric H. pylori infection.

A community-based study of Helicobacter pylori therapy using the strategy of test, treat, retest, and re-treat initial treatment failures

BACKGROUND

Although eradication of Helicobacter pylori infection can decrease the risk of gastric cancer, the optimal regimen for treating the general population remains unclear. We report the eradication rate (intention-to-treat and per protocol) of a community-based H. pylori therapy using the strategy of test, treat, retest, and re-treat initial treatment failures.

MATERIALS AND METHODS

In 2004, a total of 2658 residents were recruited for 13C-urea breath testing. Participants with positive results for infection received a standard 7-day triple therapy (esomeprazole 40 mg once daily, amoxicillin 1 g twice daily, and clarithromycin 500 mg twice daily), and a 10-day re-treatment (esomeprazole 40 mg once daily, amoxicillin 1 g twice daily, and levofloxacin 500 mg once daily) if the follow-up tests remained positive. Both H. pylori status and side-effects were assessed 6 weeks after treatment.

RESULTS

Among 886 valid reporters, eradication rates with initial therapy were 86.9% (95% confidence interval [CI]: 84.7-89.1%) and 88.7% (95%CI: 86.5-90.9%) by intention-to-treat and per protocol analysis, respectively. Re-treatment eradicated infection in 91.4% (95%CI: 86-96.8%) of 105 nonresponders. Adequate compliance was achieved in 798 (90.1%) of 886 subjects receiving the initial treatment and in all 105 re-treated subjects. Mild side-effects occurred in 24% of subjects. Overall intention-to-treat and per protocol eradication rates were 97.7% (95%CI: 96.7-98.7%) and 98.8% (95%CI: 98.5-99.3%), respectively, which were only affected by poor compliance (odds ratio, 3.3; 95%CI, 1.99-5.48; p < .0001).

CONCLUSIONS

A comprehensive plan using drugs in which the resistance rate is low in a population combined with the strategy of test, treat, retest, and re-treat of needed can result in virtual eradication of H. pylori from a population. This provides a model for planning country- or region-wide eradication programs.

Institutional difference of antibiotic resistance of Helicobacter pylori strains in Korea

GOALS

This study was performed to evaluate whether the prevalence rates of primary antibiotic resistance in Helicobacter pylori isolates could be different between 2 institutions, which are located in the different areas in Korea, and to evaluate the effect of antibiotic resistance on the eradication rate of H. pylori.

STUDY

H. pylori were isolated from gastric mucosal biopsy specimens obtained from 113 Koreans, who did not have any eradication history. The susceptibilities of the H. pylori isolates to amoxicillin, clarithromycin, metronidazole, tetracycline, levofloxacin, and moxifloxacin were examined according to the agar dilution method by 1 technician.

RESULTS

All of these patients were treated with the same regimen, proton pump inhibitor-amoxicillin-clarithromycin triple therapy. There was a statistical difference in resistance to metronidazole, levofloxacin, and moxifloxacin among 6 antibiotics between 2 institutions located in Seoul and Gyeonggi province. The rates of eradication were 94.2% for the clarithromycin and amoxicillin-susceptible strains, and 42.8% for the amoxicillin-susceptible and clarithromycin-resistant strains. In contrast, eradication rate was 100% for the amoxicillin-resistant strains.

CONCLUSIONS

These results show that there is institutional difference of antibiotic resistance of H. pylori, explaining the institutional difference of eradication rate of H. pylori. The resistance to clarithromycin seems to be an important determinant for the eradication by proton pump inhibitor triple therapy but resistance to amoxicillin does not have any effect.

[Helicobacter pylori resistance: who needs what treatment?]

The standard treatment recommended for eradication of Helicobacter pylori is a combination of three drugs for seven days: one proton pump inhibitor at a double dose and two antibiotics. The high risk of failure - on the order of 30% - justifies routine testing to verify eradication after this first treatment. Verification is most often conducted with a urea breath test, more rarely by endoscopy when endoscopy or gastric histology is otherwise necessary. When eradication fails, longer multidrug treatment with different antibiotics is proposed. The failure rate after second-line treatment is 9-10%. If a third treatment is necessary, bacterial culture is recommended to select antibiotics on the basis of the antibiotic susceptibility testing.

Association of antibiotic resistance and higher internalization activity in resistant Helicobacter pylori isolates

OBJECTIVES

Helicobacter pylori resistance to antibiotics is the main factor for therapy failure, while other features remain largely unknown. The aims of this study are to investigate the relationship of antibiotic resistance and in vitro internalization activity between cure and failure isolates and to determine whether failures are associated with persistence of the same predominant strain.

METHODS

Fifty-three isolates from forty-seven patients (cure group, n = 31; failure group, n = 16) receiving one of two lansoprazole-based therapies before and/or after therapy were investigated. Antibiotic susceptibility was determined by Etest. Genotyping was determined by cagA, babA, vacA and RAPD analyses. Target cells of internalization assay were AGS cells.

RESULTS

Five of six paired pre- and post-treatment isolates had the same predominant genetic profiles and exhibited similarly high internalization activities. The A2143G point mutation of the 23S rRNA gene conferred clarithromycin resistance. Moreover, increased antibiotic resistance after therapy was found for these five cases. Pre-treatment isolates from the failure group (n = 11) had higher level of internalization activity than those from the cure group (n = 31) (P = 0.00005). Antibiotic-resistant strains were significantly associated with higher internalization activity than were susceptible strains (metronidazole, P < 0.005; clarithromycin, P < 0.005).

CONCLUSIONS

Our results suggest that resistant H. pylori strains are associated with antibiotic resistance and superior internalization activity, protecting them against antibiotic treatment.

Susceptibilities to clarithromycin, amoxycillin and metronidazole of Helicobacter pylori isolates from the antrum and corpus in Tokyo, Japan, 1995-2001

The aim of this study was to determine the susceptibilities to clarithromycin, amoxycillin and metronidazole of Helicobacter pylori isolates from the antrum and corpus of Japanese patients examined during the period 1995-2001. There was an increase, from 6.2% in 1995 to 22.1% in 2000-2001, in the proportion of patients infected with clarithromycin-resistant H. pylori. Of patients infected with clarithromycin-resistant H. pylori, 39.1% were infected with both clarithromycin-susceptible and -resistant H. pylori. Furthermore, the MIC90 of clarithromycin for H. pylori rose from < 1 mg/L in 1995-1998 to 8 mg/L in 1999. In contrast, the MIC90s of amoxycillin and metronidazole were < or = 0.125 and 4 mg/L, respectively, throughout the study period. The results showed that, while most H. pylori isolates were susceptible to amoxycillin and metronidazole, resistance to clarithromycin among H. pylori isolates increased markedly in Japan during 1995-2001. The results also indicated a need to test the susceptibility of H. pylori isolates from more than two samples obtained from two different sites in the stomach of a single patient in order to diagnose the presence of clarithromycin-resistant H. pylori correctly.

Laboratory diagnosis and susceptibility profile of Helicobacter pylori infection in the Philippines

Background

Helicobacter pylori diagnosis and susceptibility profile directs the applicability of recommended treatment regimens in our setting. To our knowledge, there is no published data on the culture and local susceptibility pattern of Helicobacter pylori in the Philippines.

Methods

52 dyspeptic adult patients undergoing endoscopy from the Outpatient Gastroenterology clinic of the University of the Philippines-Philippine General Hospital underwent multiple gastric biopsy and specimens were submitted for gram stain, culture, antimicrobial sensitivity testing, rapid urease test and histology. Antimicrobial susceptibility testing was done by Epsilometer testing (Etest) method against metronidazole, clarithromycin, amoxicillin, and tetracycline.

Results

Sixty percent (60%) of the study population was positive for H. pylori infection (mean age of 44 years ± 13), 70% were males. H. pylori culture showed a sensitivity of 45% (95% CI [29.5–62.1]), specificity of 98% (95%CI [81.5–100%]), positive likelihood ratio of 19.93 (95% CI [1.254–317.04]) and a negative likelihood ratio of 0.56 (95% CI [0.406–0.772]). All H. pylori strains isolated were sensitive to metronidazole, clarithromycin, amoxicillin and tetracycline.

Conclusion

Knowledge of the antibiotic susceptibility patterns in our setting allows us to be more cautious in the choice of first-line agents. Information on antibiotic susceptibility profile plays an important role in empiric antibiotic treatment and management of refractive cases.

Trends in peptic ulcer pharmacotherapy

Considering the diseases of the stomach and duodenum, peptic ulcer has been the one with a significant clinical impact. The pathophysiology of peptic ulcer has centred on an imbalance between aggressive and protective factors. The discovery of Helicobacter pylori as a cause of peptic ulcer has changed our approach greatly towards this disease. Despite the decreasing frequency of H. pylori-induced peptic ulcers, peptic ulcer remains a major clinical problem partly because nonsteroidal anti-inflammatory drug (NSAID)-related ulcers and hospital admissions for ulcer complications associated with NSAIDs have increased in frequency. The interaction between H. pylori and NSAIDs is one of the most controversial issues in peptic ulcer. In this article, current concepts of peptic ulcer etiopathogenesis and the management of peptic ulcer according to the etiology were reviewed.

Helicobacter pylori: a microbiologist's view

Helicobacter pylori infection is known to cause a number of gastrointestinal diseases. From the standpoint of a microbiologist there are several important facets to this organism, which include the nature of the organism, it's diagnosis and the effectiveness of eradication therapy.

High-dose rabeprazole-amoxicillin versus rabeprazole-amoxicillin-metronidazole as second-line treatment after failure of the Japanese standard regimen for Helicobacter pylori infection

BACKGROUND

There is currently no optimal second-line treatment after failure of Helicobacter pylori triple therapy.

AIM

To determine effective salvage therapy after failure of lansoprazole-amoxicillin-clarithromycin.

METHODS

After failure of lansoprazole-amoxicillin-clarithromycin 123 out-patients were randomized to receive either 2-week rabeprazole (20 mg b.d.) + amoxicillin (1000 mg b.d.) (RA group) or 1-week rabeprazole (10 mg b.d.) + amoxicillin (750 mg twice b.d.) + metronidazole (250 mg b.d.) (RAM group). Eradication was assessed by the 13C-urea breath test. We also evaluated cytochrome p450 (CYP) 2C19 genotype status, determined by polymerase chain reaction - restriction fragment length polymorphism, and susceptibility to clarithromycin and metronidazole.

RESULTS

On an intention-to-treat basis, H. pylori infection cure was achieved in 37 of 63 (59%) patients in the RA group and in 49 of 60 (82%) patients in the RAM group. Per protocol-based eradication rates in the RA and RAM groups were 66% (37/56) and 88% (49/56), respectively. In both analytic sets there were significant differences between the treatment groups (P < 0.01 in each). Mild adverse events were observed in eight and five patients from the RA and RAM groups, respectively. Genetic predisposition of CYP2C19 and antibiotic resistance did not influence the treatment outcome either regimen.

CONCLUSIONS

The rabeprazole + amoxicillin + metronidazole therapy yielded satisfactory results. In contrast, the cure rate in high-dose rabeprazole + amoxicillin was below an acceptable level.

A clinical practice viewpoint: to culture or not to culture Helicobacter pylori?

Bacterial culture has played an irreplaceable role in the discovery and characterisation of Helicobacter pylori. The main topic of the present article is to critically review the role of culture in the management of H. pylori infection in clinical practice, from diagnosis to treatment. The available data suggest that H. pylori culture is an invasive, time-consuming method, offering quite low sensitivity, requiring significant cost for the patient, and which, in practice, tests very few antibiotics, with a questionable contribution to the management of non-responder patients. Therefore, whether patients should undergo (and pay for) an upper endoscopy for bacterial culture remains a debatable matter.

Fluorescence in situ hybridization vs. epsilometer test for detection of clarithromycin-susceptible and clarithromycin-resistant Helicobacter pylori strains in gastric biopsies from children

AIM

To compare the results of culture and epsilometer test with fluorescence in situ hybridization for the detection of Helicobacter pylori and the presence of clarithromycin-susceptible and clarithromycin-resistant strains in antral biopsies from children.

METHODS

Antral biopsies from 149 unselected children were investigated prospectively; 15 had previously received anti-H. pylori therapy. H. pylori status was defined by histology, rapid urease test and 13C-urea breath test. Fluorescence in situ hybridization was applied on fresh tissue with probes specific for the clarithromycin-susceptible wild type and three clarithromycin-resistant mutants. Susceptibility to clarithromycin was tested by epsilometer test in two laboratories.

RESULTS

Culture and fluorescence in situ hybridization gave negative results in all 66 H. pylori-negative children (specificity, 100%). Of 83 infected children, cultures were successful in 75 (90%), epsilometer test in 71 (86%) and fluorescence in situ hybridization in 77 (93%). Eleven children (13%) showed discrepant results between the applied methods, indicating mixed infection. Clarithromycin-resistant isolates were identified in 16 of 73 previously untreated children.

CONCLUSIONS

Primary resistance to clarithromycin is common (22%) in H. pylori isolates from children living in Germany. Fluorescence in situ hybridization is an excellent, fast method for the detection of H. pylori and clarithromycin-resistant mutants in gastric biopsies. Multiple biopsies identify mixed infections, indicating that clarithromycin-resistant and clarithromycin- susceptible strains are not evenly distributed within the stomach.

Helicobacter pylori: the challenge in therapy

For the therapeutic management of Helicobacter pylori infection, the Maastricht 2-2000 Consensus Report have introduced the concept of the 'treatment package' that considers first- and second-line eradication therapies together. According to this consensus statement, the first-line therapy for H. pylori eradication is a combination of the proton pump inhibitors (PPI) or ranitidine bismuth citrate (RBC) and claritromycin plus either amoxicillin or metronidazole. The second-line treatment is suggested to be PPI-quadruple therapy for a minimum of 7 days. If bismuth compounds are not available, PPI-based triple therapy will have to be used as a second-line treatment only after susceptibility testing. Since no considerable progress has been made during the past year in treatment regimens, there is still a need for new compounds that are specific for H. pylori, which could constitute future therapies.

[Microbiological factors that influence the eradication of Helicobacter pylori in adults and children]

AIM

To study microbiological factors of Helicobacter pylori, such as antimicrobial susceptibility and virulence, which affect the eradication of the microorganism in gastric mucosa of adult and pediatric patients.

METHODS

Fifty-five H. Pylori strains were isolated from culture of biopsy specimens from 39 adult and 16 pediatric patients. Antibiotic susceptibility was determined by agar dilution and study of virulence factors (cagA gene and alleles s1 and s2 of the vacA gene) by PCR. Outcome of treatment with amoxicillin (AMX), clarithromycin (CLR) and omeprazole was assessed by the urea breath test. We studied the relation of minimum inhibitory concentration (MIC) of AMX and CLR and presence of virulence factors with eradication of the microorganism.Results. The eradication rate was 69% (38/55), 71.7% in adults and 62.5% in children. Resistance to CLR and AMX was 14.5% and 0%, respectively. Overall eradication rates with respect to the variables studied were: 75% and 53% in strains with AMX MICs of < or = 0.01 6mg/L and > or = 0.032 mg/L (range < or = 0.008-0.5) (p > 0.05), 79% and 12% in strains with clarithromicina MICs of < 1 mg/L and > or = 1mg/L (range # 0.008-64) (p < 0.05), 79% and 54% in cagA+ and cagA strains (p > 0.05) and 82% and 62% in s1 and s2 strains (p > 0.05), respectively.

CONCLUSIONS

H. pylori strains with higher amoxicillin and clarithromycin MICs, and cagA and vacA s2 strains were related with lower rates of eradication in both adult and pediatric populations treated with amoxicillin, clarithromycin and omeprazole.

High prevalence of cagA- and babA2-positive Helicobacter pylori clinical isolates in Taiwan

Two virulence markers, cagA and babA2, were characterized by PCR in 101 Helicobacter pylori isolates from a population in Taiwan. cagA was detected in 99% of the isolates, while babA2 was present in all of the isolates. Base deletions and substitutions at the forward babA2 primer annealing sites were found. Given their high prevalence, cagA and babA2 cannot be useful markers for predicting the high-risk patients of H. pylori infection in Taiwan.