Fluoroquinolone resistance in Helicobacter pylori: role of mutations at position 87 and 91 of GyrA on the level of resistance and identification of a resistance conferring mutation in GyrB

Background and Aims: Fluoroquinolone‐containing regimens have been suggested as an alternate to standard triple therapy for the treatment of Helicobacter pylori infections. To determine the relationship between fluoroquinolone resistance and mutations of GyrA and GyrB in H. pylori, we exchanged the mutations at positions 87and 91 of GyrA among fluoroquinolone‐resistant clinical isolates. GyrB of a strain with no mutations in GyrA was also analyzed to identify mechanisms of resistance to norfloxacin. Materials & Methods: Natural transformation was performed using the amplified fragment of the gyrA and gyrB gene as donor DNA. The amino acid sequences of GyrA and GyrB were determined by DNA sequencing of the gyrA and gyrB genes. Results: Norfloxacin‐resistant strains which had mutations at position 87 and 91 became susceptible when the mutations were converted to the wild type. When the mutation from Asp to Asn at position 91 was exchanged to the mutation from Asn to Lys at position 87, the MIC to levofloxacin, gatifloxacin, and sitafloxacin increased. Norfloxacin‐resistant strain TS132 with no mutations in GyrA but had a mutation at position 463 in GyrB. Transformants obtained by natural transformation using gyrB DNA of TS132 had a mutation at position 463 of GyrB and revealed resistant to norfloxacin and levofloxacin. Conclusion: Mutation from Asn to Lys at position 87 of GyrA confers higher resistance to levofloxacin and gatifloxacin than does mutation from Asp to Asn at position 91. We propose that mutation at position 463 in GyrB as a novel mechanism of fluoroquinolone resistance in H. pylori.     

Primary antibiotic resistance of Helicobacter pylori isolated from Beijing children

Background: The antimicrobials resistance of Helicobacter pylori (H. pylori) was able to sharply decline the eradication rate of H. pylori both in adults and children, but there are limited studies about the primary antibiotic resistance and the related gene mutations, specifically in China. Materials and Methods: The primary resistance to 9 antibiotics of 73 H. pylori strains isolated from gastric biopsies of children recruited at Beijing Children’s Hospital was assessed, and the mutations in 23S rRNA gene of 65 macrolide‐resistant strains and in gyrA and gyrB of 12 quinolone‐resistant strains were investigated. Results: The resistance rate to clarithromycin, azithromycin, metronidazole, levofloxacin, moxifloxacin, and rifampicin was 84.9%, 87.7%, 61.6%, 13.7%, 15.1%, and 6.8%, respectively. No resistance to amoxicillin, gentamicin, and tetracycline was observed. Dual, triple, and quadruple antibacterial resistant percentage was 46.6% (34/73), 15.1% (11/73), and 2.7% (2/73), respectively. The gene mutation rate of A2142C, A2142G, and A2143G in 23S rRNA gene was 1.5% (1/65), 6.2% (4/65), and 84.6% (55/65), respectively. The detection rate of mutations of Asn87, Asp91, and Met191 in GyrA was 41.7% (5/12), 25% (3/12), and 25% (3/12), respectively. Conclusion: The high prevalence of primary antibiotic resistance was out of expectation in H. pylori strains isolated from the children in Beijing. Antibiotic susceptibility should be made clear before the antibiotic was used in the anti‐H. pylori therapy in this population. The A2143G was the most populated mutation in macrolide‐resistant strains, and Asn87 and Asp91 of GyrA were the most common mutation points in quinolone resistance strains.     

Mutations of Helicobacter pylori associated with fluoroquinolone resistance in Korea

Background and Aim: Fluoroquinolone resistance of Helicobacter pylori is known to be dependent on mutations in the QRDR of gyrA. This study was performed to investigate the distribution of gyrA point mutations and to evaluate the impact of the mutations on second‐line H. pylori eradication therapy. Methods: After H. pylori isolation from gastric mucosal specimens, fluoroquinolone resistance was examined using the agar dilution method. DNA sequencing of the QRDR of gyrA was performed in 89 fluoroquinolone‐resistant and 27 fluoroquinolone‐susceptible isolates. Transformation experiments were performed to confirm mutations in the resistant strains. The eradication rates of moxifloxacin‐containing triple therapy were evaluated depending on the resistance of fluoroquinolone. Results: The gyrA mutations were detected in 75.3% (55 of 73 strains) of the primary resistant strains and 100% (16 strains) of the secondary resistant strains. The most common mutations were Asp‐91 (36.0%) and Asn‐87 (33.7%). The MIC values in the transformed strains differed depending on the gyrA mutations, N87, and D91. Six patients with fluoroquinolone‐resistant strains received moxifloxacin‐containing triple therapy as the second‐line therapy, and two of three patients with Asn‐87 mutations (66.7%) failed in the eradication. By contrast, three patients with Asp‐91 mutations had successful eradication treatment. Conclusions: Fluoroquinolone resistance of H. pylori was caused by gyrA Asn‐87 and Asp‐91 point mutations. The Asn‐87 mutation seems to be an important determinant of failure of fluoroquinolone‐containing triple eradication therapy based on eradication results.     

Analysis of antibiotic susceptibility patterns of Helicobacter pylori isolates from Malaysia

Background: The prevalence of antibiotic resistance varies in geographic areas. The information on the antibiotic susceptibility patterns of Helicobacter pylori (H. pylori) in our local setting is therefore relevant as a guide for the treatment options. Objective: This study was conducted to determine the primary resistance rates among H. pylori isolated from Malaysian patients. Materials and methods: Biopsy samples were obtained from the stomach antrum and corpus of 777 patients from September 2004 until 2007. H. pylori isolated from these patients were then subjected to minimum inhibitory concentration (MICs) determination using E‐test method, against metronidazole, clarithromycin, levofloxacin, ciprofloxacin, amoxicillin, and tetracycline. Results: From 777 patients, 119 were positive for H. pylori where a total of 187 strains were isolated. The resistance rates were noted to be 37.4% (metronidazole), 2.1% (clarithromycin), 1% (levofloxacin and ciprofloxacin), and 0% (amoxicillin and tetracycline). Different resistance profiles were observed among isolates from the antrum and corpus of 13 patients. Resistance to one type of antibiotic was observed in 36.4% of the strains where mono‐resistance to metronidazole was the most common. Resistance to ≥2 antibiotics was noted in 3.3% of isolates. High metronidazole MICs of ≥256 μg/mL were observed among the resistant strains. Conclusions: The resistance rates of the antibiotics used in primary treatment of H. pylori infections in Malaysia are low, and multi‐antibiotic‐resistant strains are uncommon. Infections with mixed populations of metronidazole‐sensitive and ‐resistant strains were also observed. However, the high metronidazole MIC values seen among the metronidazole‐resistant strains are a cause for concern.     

Levofloxacin susceptibility testing for Helicobacter pylori in China: comparison of E-test and disk diffusion method

Background: The aims of this study were to compare disk diffusion with E‐test method for levofloxacin susceptibility testing of Helicobacter pylori and standardized breakpoints for disk diffusion as a stable and reliable method for determining qualitative levofloxacin susceptibility. Materials and Methods: We determined the levofloxacin susceptibility of 45 H. pylori strains isolated from Chinese patients by the E‐test method. Disk diffusion was evaluated as an alternative method to determine susceptibility and compared with the E‐test results by linear regression analysis. Results: The minimum inhibitory concentration (MIC) values tested by E‐test method ranged from 0.047 to 32 μg/mL. Resistance to levofloxacin was detected in 16 (35.6%) isolates. The levofloxacin disk zone sizes obtained by disk diffusion method correlated well (r² = .877) with the MICs obtained by E‐test method. As a consequence of regression analysis, isolates with inhibition diameters <12 mm were considered resistant to levofloxacin. There was 100% agreement between the two methods for levofloxacin, applying the regression‐based breakpoints. Conclusions: The disk diffusion method is equivalent to the E‐test method for testing levofloxacin susceptibility of H. pylori strains; it is more practical and inexpensive, and it is suitable for the analysis of a small number of isolates compared with the E‐test method.     

Nonbismuth quadruple (concomitant) therapy: empirical and tailored efficacy versus standard triple therapy for clarithromycin-susceptible Helicobacter pylori and versus sequential therapy for clarithromycin-resistant strains

Background:  Using quadruple clarithromycin‐containing regimens for Helicobacter pylori eradication is controversial with high rates of macrolide resistance. Aim:  To evaluate antibiotic resistance rates and the efficacy of empirical and tailored nonbismuth quadruple (concomitant) therapy in a setting with cure rates <80% for triple and sequential therapies. Methods:  209 consecutive naive H. pylori‐positive patients without susceptibility testing were empirically treated with 10‐day concomitant therapy (proton pump inhibitors (PPI), amoxicillin 1 g, clarithromycin 500 mg, and metronidazole 500 mg; all drugs b.i.d.). Simultaneously, 89 patients with positive H. pylori culture were randomized to receive triple versus concomitant therapy for clarithromycin‐susceptible H. pylori, and sequential versus concomitant therapy for clarithromycin‐resistant strains. Eradication was confirmed with ¹³C‐urea breath test or histology 8 weeks after completion of treatment. Results:  Per‐protocol (PP) and intention‐to‐treat eradication rates after empirical concomitant therapy without susceptibility testing were 89% (95%CI:84–93%) and 87% (83–92%). Antibiotic resistance rates were: clarithromycin, 20%; metronidazole, 34%; and both clarithromycin and metronidazole, 10%. Regarding clarithromycin‐susceptible H. pylori, concomitant therapy was significantly better than triple therapy by per protocol [92% (82–100%) vs 74% (58–91%), p = 0.05] and by intention to treat [92% (82–100%) vs 70% (57–90%), p = 0.02]. As for antibiotic‐resistant strains, eradication rates for concomitant and sequential therapies were 100% (5/5) vs 75% (3/4), for clarithromycin‐resistant/metronidazole‐susceptible strains and 75% (3/4) vs 60% (3/5) for dual‐resistant strains. Conclusions:  Empirical 10‐day concomitant therapy achieves good eradication rates, close to 90%, in settings with multiresistant H. pylori strains. Tailored concomitant therapy is significantly superior to triple therapy for clarithromycin‐susceptible H. pylori and at least as effective as sequential therapy for resistant strains.     

Clarithromycin–Amoxycillin‐Containing Triple Therapy: A Valid Empirical First‐Line Treatment for Helicobacter pylori Eradication in Hong Kong?

Background: Recent studies have suggested the eradication rate for Helicobacter pylori infection with standard amoxycillin–clarithromycin‐containing triple therapy as first‐line treatment have fallen below 80%. Levofloxacin‐containing triple therapy was proposed as an alternative. The aim of this study is to compare the efficacy and tolerability of the standard 7‐day clarithromycin‐containing triple therapy against the 7‐day levofloxacin‐containing triple therapy, and to assess whether the classical triple therapy is still valid as empirical first‐line treatment for H. pylori infection in Hong Kong. Methods: Three hundred consecutive H. pylori‐positive patients were randomized to receive either 1 week of EAL (esomeprazole 20 mg b.d., amoxycillin 1 g b.d., and levofloxacin 500 mg daily) or EAC (esomeprazole 20 mg b.d., amoxycillin 1 g b.d., and clarithromycin 500 mg b.d.). H. pylori status was rechecked by ¹³C‐urea breath test 6 weeks after treatment. Patients who failed either of the first‐line eradication therapy were invited to undergo H. pylori susceptibility testing. Results: H. pylori eradication was achieved in 128 of 150 (85.3%) patients in EAL and 139 of 150 (92.7%) patients in EAC groups, respectively (p = .043), for both intention‐to‐treat and per‐protocol analysis. More patients in the clarithromycin‐ than the levofloxacin‐containing therapy group developed side effects from the medication (21.3% vs 13.3%, p = .060). Nine patients (six from the EAL group and three from the EAC group) who failed their corresponding eradication therapy returned for susceptibility testing. All nine isolates were highly resistant to levofloxacin (minimum inhibitory concentration or MIC > 32 μg/mL), whereas only two of the six isolates from the EAL group were resistant to clarithromycin (MIC > 0.5 μg/mL). Conclusions: The standard 7‐day clarithromycin‐containing triple therapy is still valid as the most effective empirical first‐line eradication therapy for H. pylori infection in Hong Kong, as prevalence of primary resistance of H. pylori to amoxycillin and clarithromycin remains low. Patients who failed their empirical first‐line eradication therapy should undergo H. pylori susceptibility testing to guide further treatment.     

Primary antibiotic resistance and associated mechanisms in Helicobacter pylori isolates from Senegalese patients

Background

Antibiotic combination therapy for Helicobacter pylori eradication must be adapted to local resistance patterns, but the epidemiology of H. pylori resistance to antibiotics is poorly documented in Africa. The aim was to determine the antibiotic resistance rates, as well as the associated molecular mechanisms, of strains isolated in Dakar, Senegal.

Methods

One hundred and eight H. pylori strains were isolated between 2007 and 2009 from 108 patients presenting with upper abdominal pain to the Gastroenterology Department of Le Dantec Hospital. Antimicrobial susceptibility testing was performed for amoxicillin, clarithromycin, metronidazole, levofloxacin and tetracyclin using the E-test method. Mutations in the 23S rRNA gene of clarithromycin-resistant strains and in gyrA and gyrB of levofloxacin-resistant strains were investigated.

Results

Isolates were characterized by no resistance to amoxicillin (0%), tetracycline (0%), and very low rate of resistance to clarithromycin (1%), but a high rate of resistance to metronidazole (85%). The clarithromycin-resistant strain displayed the A2143G mutation. A worrying rate of levofloxacin resistance was detected (15%). N87I and D91N were the most common mutations in the quinolone-resistance-determining region of gyrA.

Conclusions

The first-line empirical regimen for H. pylori eradication in Senegal should include clarithromycin. Increasing rates of fluoroquinolone resistance detected should discourage the use of levofloxacin-containing regimens without prior antimicrobial susceptibility testing.     

Vitamin C and E supplements to lansoprazole-amoxicillin-metronidazole triple therapy may reduce the eradication rate of metronidazole-susceptible Helicobacter pylori infection

Aim. To test whether vitamin C and E supplements to triple therapy can improve the Helicobacter pylori eradication rate and gastric inflammation. Methods. A total of 104 H. pylori‐infected patients were randomized to receive: either lansoprazole, amoxicillin, and metronidazole twice daily for 1 week (triple‐only group) or lansoprazole, amoxicillin, metronidazole plus vitamin C (250 mg) and vitamin E (200 mg) twice daily for 1 week, followed immediately by vitamin C and E once daily for 6 consecutive weeks (triple‐plus‐vitamin group). Eight weeks after the completion of triple therapy, patients were assessed for the effectiveness of H. pylori eradication. The severity of gastric inflammation in histology was assessed for the acute and chronic inflammation scores. Results. Intention‐to‐treat and per‐protocol eradication rates were 59.1% and 64.4% in the triple‐only group, and 40% and 44% in the triple‐plus‐vitamin group. In the patients infected with metronidazole susceptible isolates, the triple‐only group had a higher intention‐to‐treat eradication rate than those in the triple‐plus‐vitamin group (80% vs. 53.1%, p < .01). However, for the metronidazole resistance isolates, the intention‐to‐treat eradication rates between the two groups were not different (26.3% vs. 21.7%, p = NS). The improvements of both acute and chronic inflammation scores in histology were not different between the two groups. Conclusion. Adding vitamin C and E to triple therapy cannot improve the H. pylori eradication rate and gastric inflammation. For patients with metronidazole susceptible strain infection, adding these vitamins may even reduce the eradication rate of triple therapy.     

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.     

The bifidogenic growth stimulator inhibits the growth and respiration of Helicobacter pylori

Background: Triple therapy with amoxicillin, clarithromycin, and a proton‐pump inhibitor is a common therapeutic strategy for the eradication of Helicobacter pylori (H. pylori). However, frequent appearance of clarithromycin‐resistant strains is a therapeutic challenge. While various quinones are known to specifically inhibit the growth of H. pylori, the quinone 1,4‐dihydroxy‐2‐naphthoic acid (DHNA) produced by Propionibacterium has strong stimulating effect on Bifidobacterium. We were interested to see whether DHNA could inhibit the growth of H. pylori in in vitro or in vivo experimental setting. Materials and Methods: The minimum inhibitory concentration (MIC) of DHNA was determined by the agar dilution method. The inhibitory action of DHNA on the respiratory activity was measured by using an oxygen electrode. Germ‐free mice infected with H. pylori were given DHNA in free drinking water containing 100 μg/mL for 7 days. Results: DHNA inhibited H. pylori growth at low MIC values, 1.6–3.2 μg/mL. Likewise, DHNA inhibited clinical isolates of H. pylori, resistant to clarithromycin. However, DHNA did not inhibit other Gram negative or anaerobic bacteria in the normal flora of the human intestine. Both H. pylori cellular respiration and adenosine 5′‐triphosphate (ATP) generation were dose‐dependently inhibited by DHNA. Similarly, the culture filtrates of propionibacterial strains inhibited the growth of H. pylori, and oral administration of DHNA could eradicate H. pylori in the infected germ‐free mice. Conclusions: The bifidogenic growth stimulator DHNA specifically inhibited the growth of H. pylori including clarithromycin‐resistant strains in vitro and its colonization activity in vivo. The bactericidal activity of DHNA was via inhibition of cellular respiration. These actions of DHNA may have clinical relevance in the eradication of H. pylori.     

Antibiotic resistance of Helicobacter pylori in Mazandaran, North of Iran

Background: The aim of this study was to investigate the prevalence of resistances in Helicobacter pylori against commonly used antibiotics including metronidazole, clarithromycin, amoxicillin, and tetracycline in Iranian patients. Methods: H. pylori isolates were collected from gastric biopsies from patients referred for upper gastrointestinal endoscopy at Tooba Medical Center, Sari, Iran, from 2007 to 2010. None of them had been using antibiotics for at least 8 months. H. pylori was identified based on morphological shape and positive biochemical tests for catalase, oxidase, and urease activity. Antibiotic resistance for metronidazole, clarithromycin, amoxicillin, and tetracycline was investigated by using epsilometer test. Resistance was defined by minimal inhibitory concentration (MIC) > 0.5 mg/L for amoxicillin (AMX), >4 mg/L for tetracycline (TET), >8 mg/L for metronidazole (MTZ), and >1 mg/L for clarithromycin (CLR). Results: Strains were collected from 132 patients, mean age 45.8 years, 52 (39%) were women. Patients had diverse diagnoses: gastritis 42 (31.8%), duodenal ulcer 45 (34%), gastric cancer 15 (11.3%), or gastric ulcer 30 (22.7%). The prevalences of resistance of H. pylori strains isolated from the patients were 73.4% for metronidazole, 30% for clarithromycin, 6.8% for amoxicillin, and 9% for tetracycline. Twenty‐eight (21.2%) were double resistant to MTZ‐CLR, 16 (12.1%) showed triple resistance to MTZ‐CLR‐AMX, and 8 (6%) were resistant to all four tested antibiotics (MTZ‐CLR‐AMX‐TET). No associations were detected between multiple resistant strains and clinical manifestations (p > .05). Conclusions: The prevalence of H. pylori antibiotic resistance to metronidazole and clarithromycin was high in Iran consistent with the reported low success rates for H. pylori treatment in this country.     

Increased primary resistance to recommended antibiotics negatively affects Helicobacter pylori eradication

Objective. To evaluate the efficacy of two commonly employed treatments for Helicobacter pylori infection and the impact of bacterial resistance to antibiotics on eradication rate. Methods. Ninety‐two consecutive H. pylori‐positive patients with active peptic ulcer disease were randomly enrolled to receive a 7‐day treatment with either lansoprazole 30 mg plus amoxicillin 1 g and clarithromycin 500 mg [all twice a day (b.i.d.), Group A, n = 46]; or bismuth subcitrate 125 mg four times a day (q.i.d.) plus tetracycline 500 mg q.i.d and furazolidone 200 mg b.i.d. (Group B, n = 46) H. pylori status was reassessed 30 days after completion of the therapy and bacterial resistance to the antibiotics was investigated using an in vitro assay. Results. Five patients from each study group were lost to follow up. Both treatments resulted in similar H. pylori eradication rate: 66–60% (per protocol), 59–52% (intention‐to‐treat) in Groups A and B, respectively (non significant). However, eradication improved to 79% in the absence of H. pylori resistance to clarithromycin or amoxicillin. Conclusion. Primary resistance to clarithromycin or amoxicillin may underscore a potentially serious problem for the eradication of H. pylori infection. Testing for bacterial resistance may become necessary to improve therapeutic efficacy.     

Mucoid Helicobacter pylori isolates with fast growth under microaerobic and aerobic conditions

Background: Helicobacter pylori is microaerobic and turns into coccoid under aerobic conditions. In this study, two mucoid strains, A and D, were isolated from gastric biopsies which grew well on blood agar after 24‐hour incubation under aerobic as well as microaerobic conditions. The aim of this study was to identify these strains and compare their growth under aerobic and microaerobic conditions with that of control H. pylori. Materials and Methods: The two isolates A and D were identified as H. pylori according to microscopic morphology, urease, catalase and oxidase tests. Their growth under humidified aerobic and microaerobic conditions was compared with that of control H. pylori which grew only under microaerobic conditions. They were further identified by amplification of 16S rRNA, vacA alleles, cagA and ureAB genes by PCR. Their susceptibility to current antimicrobials was also examined. Results: The strains A and D produced mucoid colonies under aerobic and microaerobic conditions after 24‐hour, exhibiting the typical spiral morphology of H. pylori. The results of urease, catalase and oxidase tests were positive. Sequencing of amplified products showed 99–100% homology with those of the reference H. pylori strains in GenBank. Both strains exhibited resistance to the high concentrations of antimicrobials. Conclusions: This study reports the isolation of two mucoid strains of H. pylori with confluent growth under aerobic and microaerobic conditions. It appears that production of exopolysaccharide (EXP) could serve as a physical barrier to reduce oxygen diffusion into the bacterial cell and uptake of antibiotics. EXP protected the mucoid H. pylori isolates against stressful conditions, the result of which could be persistence of bacterial infection in the stomach.     

Eradication of Helicobacter pylori in children in Vietnam in relation to antibiotic resistance

Background: Low Helicobacter pylori eradication rates are common in pediatric trials especially in developing countries. The aim of the study was to investigate the role of antibiotic resistance, drug dosage, and administration frequency on treatment outcome for children in Vietnam. Materials and Methods: Antibiotics resistance of H. pylori was analyzed by the Etest in 222 pretreatment isolates from children 3–15 years of age who were originally recruited in a randomized trial with two treatment regiments: lansoprazole with amoxicillin and either clarithromycin (LAC) or metronidazole (LAM) in two weight groups with once‐ or twice‐daily administration. The study design was an observational study embedded in a randomized trial. Results: The overall resistance to clarithromycin, metronidazole, and amoxicillin was 50.9%, 65.3%, and 0.5%, respectively. In LAC, eradication was linked to the strains being susceptible to clarithromycin (78.2% vs 29.3%, p = .0001). Twice‐daily dosage of proton‐pump inhibitor (PPI) and clarithromycin was more effective for eradication than once‐daily dosage for resistant strains (50.0% vs 14.7%, p = .004) and tended to be so also for sensitive strains (87.5% vs 65.2%, p = .051). Exact antibiotic dose per body weight resulted in more eradication for resistant strains (45.3% vs 8.0%, p = .006). These differences were less pronounced for the LAM regimen, with twice‐daily PPI versus once daily for resistant strains resulting in 69.2% and 50.0% eradication (p = .096), respectively. Conclusions: Helicobacter pylori clarithromycin resistance was unexpectedly high in young children in Vietnam. Clarithromycin resistance was an important cause for eradication treatment failure. Twice‐daily administration and exact antibiotic dosing resulted in more eradicated infections when the strains were antibiotic resistant, which has implications for the study design in pediatric H. pylori eradication trials.     

The evolution of Helicobacter pylori antibiotics resistance over 10 years in Beijing, China

Objectives: To evaluate Helicobacter pylori antibiotics resistance evolution from 2000 to 2009 to amoxicillin, clarithromycin, metronidazole, tetracycline, levofloxacin and moxifloxacin in Beijing, China. Methods: A total of 374 H. pylori strains isolated from 374 subjects who had undergone upper gastrointestinal endoscopy from 2000 to 2009 were collected and examined by E‐test method for antibiotics susceptibility. Results: The average antibiotics resistance rates were 0.3% (amoxicillin), 37.2% (clarithromycin), 63.9% (metronidazole), 1.2% (tetracycline), 50.3% (levofloxacin) and 61.9% (moxifloxacin). Overall resistance to clarithromycin, metronidazole, and fluoroquinolone increased annually (from 14.8 to 65.4%, 38.9 to 78.8%, and 27.1 to 63.5%, in 2000 or 2006–2007 to 2009, respectively). The secondary resistance rates were much higher than primary rates to these antibiotics, which also increased annually in recent 10 years. Conclusions: The trend of clarithromycin, metronidazole, and fluoroquinolone resistance of H. pylori increased over time and the resistance to amoxicillin and tetracycline was infrequent and stable in Beijing. Clarithromycin, metronidazole, and fluoroquinolone should be used with caution for H. pylori eradication treatment.     

The relationship between consumption of antimicrobial agents and the prevalence of primary Helicobacter pylori resistance

Background. Primary and acquired resistance to the antimicrobial agents is a primary reason for the failure of Helicobacter pylori eradication therapies. We assessed the primary antibiotic resistance rates of H. pylori to three different antibiotics and its relationship due to the annual antibiotic consumption in Japan during the period prior to approval of anti‐H. pylori therapy in Japan. Materials and Methods. Antibiotic susceptibility was tested using the agar dilution method for clarithromycin, amoxicillin and metronidazole. Isolates were considered resistant when the MIC value was > 8 mg/l for metronidazole, > 1 mg/l for clarithromycin and < 0.5 mg/l for amoxicillin. Results. Helicobacter pylori isolates were obtained from 593 Japanese patients from 1995 to 2000. Primary resistance of H. pylori to clarithromycin, metronidazole and amoxicillin was found in 11%, 9% and 0.3% strains, respectively. The proportion with clarithromycin resistance significantly increased from 7% in 1997–98 to 15.2% in 1999–2000 (p = .003). During the same period the metronidazole resistance rate also increased from 6.6% in 1997–98 to 12% in 1999–2000 (p = .02). The prevalence of clarithromycin and metronidazole was related to the annual consumption of these antimicrobial agents. Conclusion. Resistance rates for both clarithromycin and metronidazole appear to reflect the annual consumption of these agents. The high rate of clarithromycin resistance in Japan suggests that the effectiveness of clarithromycin‐based therapies may be compromised in the near future.     

Antibiotics resistance of Helicobacter pylori in children with upper gastrointestinal symptoms in Hangzhou,China

Background

The decreasing eradication rate of Helicobacter pylori is mainly because of the progressive increase in its resistance to antibiotics. Studies on antimicrobial susceptibility of H. pylori in children are limited. This study aimed to investigate the resistance rates and patterns of H. pylori strains isolated from children.

Materials and Methods

Gastric mucosa biopsy samples obtained from children who had undergone upper gastrointestinal endoscopy were cultured for H. pylori, and susceptibility to six antibiotics (clarithromycin, amoxicillin, gentamicin, furazolidone, metronidazole, and levofloxacin) was tested from 2012‐2014.

Results

A total of 545 H. pylori strains were isolated from 1390 children recruited. The total resistance rates of H. pylori to clarithromycin, metronidazole, and levofloxacin were 20.6%, 68.8%, and 9.0%, respectively. No resistance to amoxicillin, gentamicin, and furazolidone was detected. 56.1% strains were single resistance, 19.6% were resistant to more than one antibiotic, 16.7% for double resistance, and 2.9% for triple resistance in 413 strains against any antibiotic. And the H. pylori resistance rate increased significantly from 2012‐2014. There was no significant difference in the resistance rates to clarithromycin, metronidazole, and levofloxacin between different gender, age groups, and patients with peptic ulcer diseases or nonulcer diseases.

Conclusions

Antibiotic resistance was indicated in H. pylori strains isolated from children in Hangzhou, and it increased significantly during the 3 years. Our data strongly support current guidelines, which recommend antibiotic susceptibility tests prior to eradication therapy.     

A prospective,randomized study of quadruple therapy and high-dose dual therapy for treatment of Helicobacter pylori resistant to both metronidazole and clarithromycin

Background and Aim. Failure of primary anti‐H. pylori therapy results in a high rate of antimicrobial resistance. Here, we investigated the efficacy of high‐dose dual therapy and quadruple therapy as salvage treatments for eradication of H. pylori resistant to both metronidazole and clarithromycin. Patients and Methods. Patients with at least one treatment failure and infected with H. pylori resistant to both metronidazole and clarithromycin, were randomized to receive either omeprazole 4 × 40 mg and amoxicillin 4 × 750 mg; or omeprazole 2 × 20 mg, bismuthcitrate 4 × 107 mg, metronidazole 4 × 500 mg and tetracycline 4 × 500 mg. Both regimens were given for 14 days. In cases of persistent infection, a cross‐over therapy was performed. Results. Eighty‐four patients were randomized. Cure of H. pylori infection was achieved in 31 patients after dual therapy and in 35 patients after quadruple therapy (per protocol: 83.8% (95% CI, 67.9–93.8) and 92.1% (95% CI, 78.6–98.3), respectively (p = 0.71); intention to treat: 75.6% (95% CI: 59.7–87.6) and 81.4% (95% CI: 66.6–91.6), respectively (p = 0.60)). Cross‐over therapy was performed in six of nine patients, four of whom were cured of the infection. Conclusion. Both high‐dose dual therapy and quadruple therapy are effective in curing H. pylori infection resistant to both metronidazole and clarithromycin in patients who experienced previous treatment failures.     

Application of real-time PCR stool assay for Helicobacter pylori detection and clarithromycin susceptibility testing in Brazilian children

Background: Helicobacter pylori ClariRes assay is a novel commercially available real‐time PCR assay allowing H. pylori detection and clarithromycin susceptibility testing in either gastric biopsy or stool specimens. Objective: The aim of this study was to validate the novel biprobe real‐time assay in stool specimens from 217 dyspeptic children. Methods: DNA from gastric biopsies and stool specimens were obtained and submitted to the biprobe real time assay for H. pylori detection and clarithromycin susceptibility testing. Results: The sensitivity, specificity, and test accuracy were 69, 100 and 93.9% for the detection of H. pylori infection and 83.3, 100 and 95.6%, for detection of clarithromycin resistance. Conclusion: This assay proved to be appropriate for H. pylori clarithromycin susceptibility testing, particularly in children populations where a high prevalence of clarithromycin‐resistant strains is suspected.