Antimicrobial activities of synthetic bismuth compounds against Clostridium difficile.
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Clostridium difficile is a major nosocomial pathogen responsible for pseudomembranous colitis and many cases of antibiotic-associated diarrhea. Because of potential relapse of disease with current antimicrobial therapy protocols, there is a need for additional and/or alternative antimicrobial agents for the treatment of disease caused by C. difficile. We have synthesized a systematic series of 14 structurally simple bismuth compounds and assessed their biological activities against C. difficile and four other gastrointestinal species, including Helicobacter pylori. Here, we report on the activities of six compounds that exhibit antibacterial activities against C. difficile, and some of the compounds have MICs of less than 1 microgram/ml. Also tested, for comparison, were the activities of bismuth subcitrate and ranitidine bismuth citrate obtained from commercial sources. C. difficile and H. pylori were more sensitive both to the synthetic bismuth compounds and to the commercial products than were Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis, and the last three species were markedly resistant to the commercial bismuth salts. Testing with human foreskin fibroblast cells revealed that some of the synthetic compounds were more cytotoxic than others. Killing curves for C. difficile treated with the more active compounds revealed rapid death, and electron microscopy showed that the bismuth of these compounds was rapidly incorporated by C. difficile. Energy dispersive spectroscopy X-ray microanalysis of C. difficile cells containing electron-dense material confirmed the presence of internalized bismuth. Internalized bismuth was not observed in C. difficile treated with synthetic bismuth compounds that lacked antimicrobial activity, which suggests that the uptake of the metal is required for killing activity. The nature of the carrier would seem to determine whether bismuth is transported into susceptible bacteria like C. difficile. (+info)
Helicobacter pylori eradication with proton pump inhibitor-based triple therapies and re-treatment with ranitidine bismuth citrate-based triple therapy.
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BACKGROUND: It has been suggested that short-term triple therapy comprising a proton pump inhibitor, plus clarithromycin and amoxycillin be used as first choice in treating H. pylori infection, while eradication failure patients should be further treated with a quadruple therapy. Nevertheless, conflicting results have been reported using these treatment regimens in different countries. METHODS: A total of 278 patients with H. pylori infection were randomised to receive one-week triple therapy, comprising clarithromycin 500 mg b.d., amoxycillin 1 g b.d., and either omeprazole 20 mg b.d. (OAC; 90 patients), or pantoprazole 40 mg b.d. (PAC; 95 patients), or lansoprazole 30 mg b.d. (LAC; 93 patients). H. pylori infection at entry, and eradication 4-6 weeks after therapy had ended, were assessed by rapid urease test and histology on biopsies from the antrum and the corpus. When eradication did not occur, patients were given a 2-week treatment comprising ranitidine bismuth citrate 400 mg b.d., tetracycline 500 mg t.d.s. and tinidazole 500 mg b.d. (RBTT). Eradication in these patients was assessed 4-6 weeks after conclusion of treatment by a further endoscopy. RESULTS: Six patients were lost to the follow-up. At the end of the first course of treatment, the overall H. pylori eradication rate was 78% (95% CI: 73-83) and 79% (95% CI: 75-84) at 'intention-to-treat' (ITT) and 'per protocol' (PP) analysis, respectively, without any statistically significant difference between treatment regimens, although a trend for better results with the omeprazole combination was observed. Moreover, H. pylori eradication was achieved in 82% (95% CI: 75-97) (ITT) and 86% (95% CI: 69-94) (PP) of 38 patients re-treated with RBTT regimen. CONCLUSIONS: Our data found that this short-term triple therapy is not a satisfactory treatment (< 80% eradication rate) for H. pylori infection. The 2-week triple therapy used as re-treatment in eradication failure patients yielded more promising results. (+info)
BACKGROUND: Although many combination therapies have been proposed, there is still interest in identifying simple, inexpensive, effective protocols that have high rates of success. AIM: To investigate the role of the new soluble form of bismuth, ranitidine bismuth citrate, in twice-a-day therapy for Helicobacter pylori infection. METHODS: Patients with histologically and culture proven H. pylori infection received ranitidine bismuth citrate 400 mg, tetracycline HCl 500 mg, and clarithromycin 500 mg, each b.d. for 14 days, followed by 300 mg ranitidine once a day for 4 additional weeks. Outcome was assessed 4 or more weeks after the end of antimicrobial therapy by repeat endoscopy with histology and culture (49 patients) or urea breath testing (14 patients). RESULTS: Sixty-three patients completed the therapy, 59 men and four women (average age 56.7 years; range 31-75 years). All patients had clarithromycin-susceptible strains prior to therapy. H. pylori infection was cured in 94% (95% CI: 85-98%). There was a therapy failure in one patient who took the medicine for only 1 day and stopped because of side-effects. Three of the isolates from treatment failures were available post-failure; two were clarithromycin-resistant and one was susceptible. Side-effects were severe in two patients (3%) and moderate in three (primarily diarrhoea). CONCLUSIONS: Twice-a-day ranitidine bismuth citrate, tetracycline, clarithromycin triple therapy was well tolerated and effective for the treatment of H. pylori infection in patients with clarithromycin-susceptible H. pylori. (+info)
The influence of metronidazole resistance on the efficacy of ranitidine bismuth citrate triple therapy regimens for Helicobacter pylori infection.
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AIM: To assess the influence of metronidazole resistance on the efficacy of ranitidine bismuth citrate-based triple therapy regimens in two consecutive studies. METHODS: In the first study, patients with a culture-proven Helicobacter pylori infection were treated with ranitidine bismuth citrate 400 mg, metronidazole 500 mg, and clarithromycin 500 mg, all twice daily for 1 week (RMC). In the second study, amoxycillin 1000 mg was substituted for clarithromycin (RMA). Susceptibility testing for metronidazole was performed with the E-test. Follow-up endoscopy was performed after >/= 4 weeks. Antral biopsy samples were taken for histology and urease test, and culture and corpus samples for histology and culture. RESULTS: 112 patients, 53 males, age 55 +/- 14 years (39 duodenal ulcer, 7 gastric ulcer and 66 gastritis) were treated with RMC, and 89 patients, 52 males, age 58 +/- 15 years (23 duodenal ulcer, 7 gastric ulcer and 59 gastritis) were treated with RMA. For RMC, intention-to-treat eradication results were 98% (59/60, 95% CI: 91-100%) and 95% (20/21, 95% CI: 76-100%) for metronidazole susceptible and resistant strains, respectively (P = 0.45). For RMA these figures were 87% (53/61, 95% CI: 76-94%) for metronidazole susceptible strains and 22% (2/9, 95% CI: 3-60%) for resistant strains (P = 0.0001). CONCLUSION: Both regimens are effective in metronidazole susceptible strains. However, in contrast to the amoxycillin-containing regimen, that containing clarithromycin is also effective in resistant strains. (+info)
Eradication of Helicobacter pylori infection after ranitidine bismuth citrate, metronidazole and tetracycline for 7 or 10 days.
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BACKGROUND: We assessed the efficacy, tolerance, and compliance of twice-daily triple therapy for Helicobacter pylori with ranitidine bismuth citrate, metronidazole and tetracycline for 7 or 10 days. METHODS: 105 subjects with H. pylori infection documented by the 13C-urea breath test were randomly assigned to a 7 or 10-day course of ranitidine bismuth citrate 400 mg b.d., metronidazole 500 mg b.d. and tetracycline 500 mg b.d. Subjects returned at the end of therapy for assessment of side-effects and pill count. A repeat 13C-urea breath test was obtained 4 or more weeks after completion of therapy and cure of infection was defined as a negative test result. RESULTS: Poor compliance (< 80% of medications) was seen in 2% of subjects randomized to 7 days of therapy and in 10% randomized to 10 days of therapy (P = N.S.). Intention-to-treat eradication rates were 56% for 7-day and 60% for 10-day therapy (P = N.S.). Per protocol eradication rates were 58% for 7-day and 61% for 10-day therapy (P = N.S.). The 10-day intention-to-treat eradication rate for males was 78% and 32% for females (P < 0.01) and per protocol eradication rates were 79% and 31%, respectively (P < 0.01). CONCLUSIONS: Despite excellent compliance and tolerance, neither 7 nor 10 days of therapy with twice-daily ranitidine bismuth citrate, metronidazole and tetracycline are adequate as a treatment of H. pylori infection. (+info)
Efficacy of a 1-week regimen of ranitidine bismuth citrate in combination with metronidazole and clarithromycin for Helicobacter pylori eradication.
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BACKGROUND: In order to improve the efficacy and simplicity of the FDA-approved regimen of ranitidine bismuth citrate (RBC) and clarithromycin dual therapy, we added an inexpensive antibiotic (metronidazole), changed the dosage scheme to twice daily dosing, and decreased the duration of therapy to 1 week. METHODS: This was an open label study in which subjects with previously untreated Helicobacter pylori infection documented by serology or endoscopy and confirmed by the 13C-urea breath test received a 1-week course of RBC 400 mg b.d., metronidazole 500 mg b.d. and clarithromycin 500 mg b.d. A repeat breath test was performed 4-6 weeks after completing therapy. RESULTS: Forty-seven out of 50 subjects completed the protocol. Intention-to-treat and per protocol cure rates were 86% and 91%, respectively. The regimen was well tolerated. Study drugs were stopped in two patients due to side-effects. The most common side-effect was self-limited diarrhoea. CONCLUSION: Twice daily RBC-based triple therapy with metronidazole and clarithromycin for 1 week is well tolerated and effective in eradicating H. pylori infection. (+info)
Spiramycin is comparable to oxytetracycline in eradicating H. pylori when given with ranitidine bismuth citrate and metronidazole.
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BACKGROUND: We have consistently achieved about 90% eradication of H. pylori with liquid bismuth, metronidazole and oxytetracycline. AIM: To test eradication and adverse events of ranitidine bismuth citrate (RBC) when given with metronidazole and either oxytetracycline or spiramycin. METHODS: One hundred and eighty-three patients were randomized to one of four 10-day regimens: RBC400OM: RBC 400 mg b.d., oxytetracycline 500 mg q.d.s.; RBC400SM: RBC 400 mg b.d., spiramycin 1 g q.d.s.; RBC200OM: RBC 200 mg q.d.s., oxytetracycline 500 mg q.d.s.; RBC200SM: RBC 200 mg q.d.s., spiramycin 1 g q.d.s. Additionally, all patients received metronidazole 400 mg q.d.s. A 14C-urea breath test was performed at 8 weeks. RESULTS: Intention-to-treat eradication rates were 94%, 91%, 94% and 89% with RBC400OM, RBC400SM, RBC200OM and RBC200SM, respectively (P = 0.81). Eradication was significantly higher in ulcer patients (97%) than in those with diagnoses other than ulcer (86%) (P = 0.009). There was a strong tendency to better eradication among those who had never smoked (100%) compared with ex-smokers (93%) and smokers (89%) (P = 0.06). Fifty-three per cent experienced at least one moderate or severe adverse event, and women had more adverse events than men (P = 0.0002). CONCLUSIONS: All four regimens had comparable efficacy and adverse events. Eradication was significantly better in ulcer patients but there was a trend to better eradication in those who smoked less, used less alcohol and exercised more. Adverse events were frequent, perhaps because of the large dose of metronidazole used, but few patients stopped treatment. (+info)
Prospective evaluation of ranitidine bismuth citrate-based triple therapy for the treatment of Helicobacter pylori infection.
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BACKGROUND: There is a need for effective and inexpensive therapy for Helicobacter pylori with good patient compliance. AIM: To evaluate a simplified twice daily schedule for treating H. pylori. METHODS: Patients infected with H. pylori (positive by CLO- and 13C-urea breath tests [UBT]) and not previously treated with anti-H. pylori therapy were treated with ranitidine bismuth citrate (RBC) and two inexpensive antibiotics (metronidazole, tetracycline) twice daily for 14 days in an open-label study. Eradication was established by a negative UBT 4 weeks after ending therapy. RESULTS: Twenty men and 30 women (age 54+/-14 years, range 26-74) were included in the study. Five patients were prematurely withdrawn (side-effects 2, took additional antibiotics 2 and surgery 1) and one patient was lost to follow-up; therefore, 44 (88%) patients completed the H. pylori eradication protocol. Per protocol (PP) cure rate was 82% (36/44 patients, 95% CI: 68-95%), and intention-to-treat cure rate was 72% (36/50 patients, 95% CI: 58-82%). Five patients (10%) developed side-effects during therapy, most commonly nausea (3 patients). Four weeks after the end of treatment, 78% (PP) of patients were symptomatically improved. CONCLUSIONS: A 2-week course of twice-daily RBC-based triple therapy was well tolerated, eradicated H. pylori in 72% (ITT) and 82% (PP) of patients, respectively, and relieved symptoms in 78%. (+info)