High Prevalence Of Metronidazole Resistance Research Articles

CagA status & genetic characterization of metronidazole resistant strains of H. pylori from: A region at high risk of gastric cancer.

The aim of study was to determine relationship between cagA and genetic characterization of metronidazole (MTZ) resistant H. pylori strains from a region at high risk of gastric cancer. 172 H. pylori strains were isolated from the patients with dyspeptic symptoms, and antimicrobial susceptibility testing for MTZ was assessed by E-test. rdxA and frxA genes were amplified using PCR among the MTZ resistant isolates. The status of the plasmid and classes 1～3 integrons were investigated in all isolates. MTZ was detected in 88 isolates (51.16%). Variations in the rdxA gene leading to alterations of amino acids in RdxA proteins were identified in all MTZ resistant strains. FrxA contained missense alterations in 55 MTZ resistant isolates, while the premature truncation of FrxA was caused by frameshift mutations in 9 MTZ resistant strains. Plasmid was found in one MTZ sensitive strain (0.58%), and none of Class 1～3 integrases gene was detected in the studied isolates. The conservative cagA fragment was obtained from all clinical isolates of H. pylori. The sequence of cagA 3' variable region in 164 strains were obtained, including East Asian-type (122, 74.39%) and Western-type (42, 25.61%). Prevalence of Western-type cagA 3' variable region was significantly higher in MTZ resistant (33.73%, 28/83) than those of MTZ-sensitive strains (17.28%, 14/81) (p=0.02). A high prevalence of MTZ resistance was found in the region, and bacterial chromosome mutations in the rdxA and frxA gene still contribute to the high-level MTZ resistance. H. pylori strains characterized with West-type cagA 3' variable region tend to acquire MTZ resistance in the region.

Reliable Efficacy of 14-Day High Dose PPI Triple Therapy for Helicobacter pylori Eradication Independent Effect of CYP2C19 Genotype and High Prevalence of Metronidazole Resistance in Thailand

Reliable Efficacy of 14-Day High Dose PPI Triple Therapy for Helicobacter pylori Eradication Independent Effect of CYP2C19 Genotype and High Prevalence of Metronidazole Resistance in Thailand

Helicobacter pylori Eradication Using a 14-day Bismuth Quadruple Therapy Among Hispanic Adults in El Paso, Texas: Preliminary Findings

Purpose: Previous studies have shown that the standard triple therapy which consists of two antibiotics, clarithromycin and amoxicillin, and a proton pump inhibitor, results in less than 80% eradication rates of H. pylori infection. A quadruple therapy consisting of three-in-one capsules containing bismuth subcitrate potassium, metronidazole, tetracycline hydrochloride plus omeprazole capsules (Pylera) for ten days was 91% PP in the U.S. and 93% ITT in Europe for eradicating H. pylori (Grade B results). An ongoing study is assessing cure rates of this therapy given for 14 days in an area with high prevalence of metronidazole resistance (i.e., adults in El Paso, Texas). Methods: Subjects were screened for H. pylorii using a urine IgG antibody test and infection status was confirmed by urea breath test. Specimens for cultures were obtained using the minimally invasive non-endoscopic oro-gastric brush method. Fifty subjects have entered and received the 14-day treatment of the combination capsules containing 420 mg of bismuth subcitrate potassium (q.i.d.), 375 mg of metronidazole (q.i.d.), 375 mg of tetracycline hydrochloride (q.i.d.) plus 20 mg of omeprazole (bid). Infection status after treatment was determined by a urea breath test administered at 45+ days. Results: The effectiveness based on PP analysis to date is 100% (lower bound of mid-P 95% CI: 82.9). The prevalence of metronidazole resistant H. pylori (≥8 μg/mL) strains was 44%. The eradication rates according to PP analysis the cure rates were 100% for both metronidazole resistant and metronidazole susceptible strains. No strain was resistant to tetracycline (i.e., all had MIC <2 μg/mL). Overall the therapy was well tolerated. Conclusion: Extending the duration to 14-days of this bismuth-containing quadruple therapy resulted in a high treatment success despite the presence of metronidazole resistance for eradication of H. pylori infections in a Hispanic population. If the excellent results continue, a head to head 10 vs. 14 days comparison will be indicated. (Disclosure: This researcher initiated study was funded by a grant from Aptalis Pharma, Inc, Bridgewater, NJ, USA.) This researcher initiated study was funded by a grant from Aptalis Pharma, Inc, Bridgewater, NJ, USA.

Phenotypic and Genetic Characterization of Antimicrobial Profiles of &lt;i&gt;Helicobacter pylori&lt;/i&gt; Strains in Cuba

The study evaluated the antibiotic resistance patterns of Helicobacter pylori strains against metronidazole and clarithromycin in a hospital in Havana, Cuba. Eighty-five percent, 22.5%, and 10% of 40 H. pylori strains investigated were resistant to metronidazole, ciprofloxacin, and clarithromycin respectively but all were susceptible to amoxicillin and tetracycline. RdxA truncation was found only in metronidazole-resistant strains. In such strains, reported are eight and two novel mutations in the rdxA and frxA genes respectively. Two-point mutations in the 23S rRNA genes of clarithromycin-resistant strains were detected. A high prevalence of metronidazole resistance was found in Cuban H. pylori strains. Mutations in the rdxA gene may contribute more significantly than frxA gene to the high level of resistance to metronidazole. This study supports the need to continue monitoring the antibiotic susceptibility in H. pylori in Cuba to guide the treatment of such infection.

Meta‐analysis: the efficacy, adverse events, and adherence related to first‐line anti‐Helicobacter pylori quadruple therapies

Owing to rising drug-resistant Helicobacter pylori infections, currently recommended proton-pump inhibitor-based triple therapies are losing their efficacy, and regimens efficacious in the presence of drug resistance are needed. To summarize the efficacy, safety and adherence of first-line quadruple H. pylori therapies in adults. Meta-regression models identified factors explaining variation in the efficacy of first-line quadruple therapies from 145 treatment arms. Estimates of average efficacy were calculated within homogeneous groups. Quadruple therapy containing a gastric acid inhibitor, bismuth, metronidazole and tetracycline was enhanced when omeprazole was included, treatment duration lasted 10-14 days, and when therapy took place in the Netherlands, Hong Kong and Australia. Treatment efficacy decreased as the prevalence of metronidazole resistance increased. Even in areas with a high prevalence of metronidazole resistance, this quadruple regimen eradicated more than 85% of H. pylori infections when it contained omeprazole and was given for 10-14 days. Furthermore, in the presence of clarithromycin resistance, this quadruple regimen eradicated 90-100% of H. pylori infections, while the currently recommended triple therapy containing clarithromycin, amoxicillin and a proton-pump inhibitor eradicated only 25-61% (P < 0.001). Adherence and adverse events for quadruple therapy were similar to currently recommended triple therapies. Guidelines should include quadruple therapy with a proton-pump inhibitor, a bismuth compound, metronidazole and tetracycline among recommended first-line anti-H. pylori therapies.

Metronidazole-resistant Helicobacter pylori in an urban Asian population.

Helicobacter pylori eradication is the mainstay in the treatment of H. pylori-associated peptic ulcer disease. Metronidazole is an important component in most eradication regimens. However, the presence of metronidazole-resistant H. pylori adversely affects the efficacy of such regimens. We aimed to study the prevalence of metronidazole resistance in our population, and the factors associated with its presence. From September 1993 to September 1996, 459 H. pylori isolates were collected and analysed. The overall resistance rate was 62.7%. The rate was significantly higher among women compared with men (P < 0.05). When the results were analysed according to each year, there was a significant increase in the resistance rate from 50.5% in the first year to 72.7% in the third year (P = 0.0039). There was a significant rise in the prevalence of metronidazole resistance over a 3-year period. The presence of metronidazole resistance adversely affects the eradication rates of nitroimidazole-based regimens. Hence, in a population with a high prevalence of metronidazole resistance, the use of non-nitroimidazole-based therapy may be more efficacious. This information on resistance rates is important for the empirical choice of antibiotic against H. pylori in a population.

One-week ranitidine bismuth citrate-based low dose clarithromycin triple therapy is superior to omeprazole-based regime for the eradication of Helicobacter pylori (H. Pylori) in Hong Kong with high prevalence of metronidazole resistance

One-week ranitidine bismuth citrate-based low dose clarithromycin triple therapy is superior to omeprazole-based regime for the eradication of Helicobacter pylori (H. Pylori) in Hong Kong with high prevalence of metronidazole resistance

One-week ranitidine bismuth citrate versus colloidal bismuth subcitrate-based anti- Helicobacter triple therapy: a prospective randomized controlled trial

OBJECTIVE: The efficacy of 1 wk bismuth triple therapy is adversely influenced by the presence of metronidazole resistance. In vitro studies suggest that ranitidine bismuth citrate (RBC) plus metronidazole exhibit synergistic activity against metronidazole resistant strains of Helicobacter pylori ( H. pylori). Whether this confers a superior clinical efficacy remains unproven. This study compared the efficacy of RBC-based triple therapy with bismuth triple therapy in eradication of H. pylori. METHODS: Patients with H. pylori-related ulcer disease or gastritis were randomized to receive either 400/mg of RBC twice daily plus 400/mg of metronidazole and 500/mg of tetracycline four times daily for 1 wk (RMT) or 120/mg of colloidal bismuth subcitrate, 400/mg of metronidazole, and 500/mg of tetracycline, all given four times daily for 1 wk (BMT). Metronidazole susceptibility was determined by the E-test and pretreatment resistance was defined as minimum inhibitory concentration ≥32/mg/L. RESULTS: Of 100 consecutive patients randomized, two patients were lost to follow-up in each group. Forty-three of 85 (51%) H. pylori isolates were metronidazole resistant. Perprotocol cure rate for RMT and BMT was 40 of 41 (98%) and 37 of 44 (84%), respectively ( p = 0.058). Intent-to-treat cure rate for RMT and BMT was 46 of 50 and 41 of 50, respectively (92% vs 82%, p = 0.23). A significantly higher eradication of metronidazole resistant H. pylori was observed in the RMT group (25 of 25, 100%) than in the BMT group (12 of 16, 75%), ( p = 0.018). Side effects observed in the two treatment groups were comparable. CONCLUSIONS: One week of RBC triple therapy with metronidazole and tetracycline is an effective anti- Helicobacter therapy. This regimen is more appropriate in areas of high prevalence of metronidazole resistance.

High prevalence of Helicobacter pylori metronidazole resistance in migrants to east London: relation with previous nitroimidazole exposure and gastroduodenal disease.

A high prevalence of metronidazole resistance in Helicobacter pylori is reported in developing countries. This study examined whether migrants referred for diagnostic gastroscopy at a United Kingdom centre (n = 54), had a higher prevalence of metronidazole resistance than subjects born in the United Kingdom attending endoscopy (n = 46). Records of nitroimidazole treatment prescribed in the United Kingdom was obtained in 83 patients to find out if there was an association between H pylori metronidazole resistance and previous ingestion of either metronidazole or tinidazole. The prevalence of metronidazole resistant isolates varied according to country of birth: Bangladesh (90%, 27 of 30), other countries (67%, 16 of 24), and United Kingdom (37%, 17 of 46) (p < 0.001). Among those born in the United Kingdom, women were more likely to harbour resistant H pylori than men (54% v 18% respectively, p = 0.01) and more likely to have a history of previous nitroimidazole ingestion (41% v 11% respectively, p = 0.02). Patients previously exposed to either metronidazole or tinidazole were more likely to harbour resistant strains (84% (27 of 32) v 41% (21 or 51), p < 0.0001). The distribution of gastroduodenal disease, assessed endoscopically, was not affected by metronidazole resistance status.

Short report: clarithromycin, an alternative to metronidazole in the triple therapy of Helicobacter pylori infection

Triple therapy for Helicobacter pylori using metronidazole is less effective in patients with a metronidazole resistant strain. Moreover, metronidazole is responsible for many side-effects. This open study examined the efficacy and side-effects of a triple treatment regimen substituting clarithromycin for metronidazole. 36 patients with a H. pylori infection, proven by culture, were treated with tripotassium dicitrato bismuthate 120 mg q.d.s., tetracycline 250 mg q.d.s. and clarithromycin 250 mg q.d.s. for 10 days. Eradication was defined as a negative culture and histological examination of antral biopsy specimens, taken at least 6 weeks after completion of the treatment. Eradication was achieved in 26 patients (72%). The treatment was well tolerated with only 4 (11%) of the patients having significant side-effects. Triple therapy with clarithromycin seems to be less effective than standard triple treatment when the prevalence of metronidazole resistance is low. It is suggested, however, that this combination could be a valuable alternative in areas with a high prevalence of metronidazole resistance.