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PubMed1997

Evolution of resistance to metronidazole and clarithromycin in Helicobacter pylori clinical isolates from Spain.

The aim of this study was to determine the frequency of resistance to amoxycillin, tetracycline, metronidazole and clarithromycin in 282 Helicobacter pylori clinical isolates from Spain and to evaluate the evolution of resistance over the five years of this study. The overall percentage of resistance was 19.9% for metronidazole and 3.5% for clarithromycin. Resistance to metronidazole rose from 9% in 1991 to 21.6% in 1995, although 33.3% resistance was found in 1993. Clarithromycin resistance was not detected in 1991 or 1992 and the rate was 4%, 3.4% and 4.4% in 1993, 1994 and 1995, respectively. No amoxycillin or tetracycline resistance was found.

Adolescent↗
PubMed1999

Antimicrobial activities of benzoxazinorifamycin (KRM-1648) and clarithromycin against Mycobacterium avium-intracellulare complex within murine peritoneal macrophages, human macrophage-like cells and human alveolar epithelial cells.

Profiles of the in-vitro antimicrobial effects of KRM-1648 and clarithromycin against Mycobacterium avium-intracellulare complex (MAC) within murine peritoneal macrophages, the THP-1 human macrophage cell line and the A-549 type II alveolar epithelial cell line were determined. MAC organisms grew more rapidly in A-549 and THP-1 cells than in murine peritoneal macrophages. Peritoneal macrophages produced significant amounts of reactive nitrogen intermediates in response to MAC infection, but A-549 and THP-1 cells did not. KRM-1648 progressively killed M. intracellulare residing in macrophages, but did not completely eliminate M. intracellulare from A-549 and THP-1 cells. Moreover, in the case of M. intracellulare-infected A-549 and THP-1 cells, bacterial regrowth was observed during the middle to late phase of cultivation. Clarithromycin exhibited moderate levels of microbicidal activity against M. intracellulare residing in peritoneal macrophages, THP-1 cells and A-549 cells. The profiles of clarithromycin-mediated killing or inhibition of the intracellular organisms in A-549 and THP-1 cells were similar to those observed for organisms within peritoneal macrophages.

Animals↗
PubMed1999

Comparative effects of omeprazole, amoxycillin plus metronidazole versus omeprazole, clarithromycin plus metronidazole on the oral, gastric and intestinal microflora in Helicobacter pylori-infected patients.

Fourteen patients with Helicobacter pylori infection were treated with 20 mg omeprazole, 1 g amoxycillin and 400 mg metronidazole bd for 7 days (OAM), and 16 patients were treated with 20 mg omeprazole, 250 mg clarithromycin and 400 mg metronidazole bd for 7 days (OCM). Saliva, gastric biopsies and faecal samples were collected before, during (day 7) and 4 weeks after treatment in order to analyse alterations of the normal microflora and to determine antimicrobial susceptibility. Both treatment regimens resulted in marked quantitative and qualitative alterations. A selection of resistant streptococcal strains were noticed in both treatment groups, most apparent in the OCM group where a shift from susceptible to resistant strains was recorded. In the OAM group, six patients had overgrowth of resistant enterobacteriaceae during treatment compared with none in the OCM group, in the gastric microflora. The MICs for Enterococcus spp. and Enterobacteriaceae in faeces increased significantly during treatment in both groups. Nine patients in the OAM group became intestinally colonized by yeasts during treatment. The total anaerobic microflora was strongly suppressed in both treatment groups, although most pronounced in the OCM group, where the frequency of clarithromycin-resistant bacteroides strains increased from 2 to 76% during treatment, and remained at 59% 4 weeks post-treatment. Even if the treatment outcome was better in the OCM group (100%) than in the OAM group (71%), the amoxycillin-based treatment might be preferable from an ecological point of view, since the qualitative alterations in terms of emergence and persistence of resistant strains seemed to be most pronounced in the clarithromycin-treated group.

Adult↗
PubMed2001

Effects of lansoprazole, clarithromycin and pH gradient on uptake of [14C]amoxycillin into rat gastric tissue.

The effect of lansoprazole and clarithromycin on the uptake of [(14)C]amoxycillin into rat gastric tissue was investigated. After oral administration of [(14)C]amoxycillin, the levels of radioactivity in gastrointestinal tissue were two to 15 times higher than those in plasma. The level of radioactivity in glandular stomach was significantly higher when lansoprazole and [(14)C]amoxycillin were administered together. After intravenous administration of [(14)C]amoxycillin, there was less radioactivity in gastric tissue than after oral administration, and co-administration of lansoprazole and clarithromycin had no obvious effect. The gastric emptying rate of [(14)C]amoxycillin was not apparently affected by the co-administration of lansoprazole and clarithromycin. In vitro uptake of [(14)C]amoxycillin into gastric tissue depended on the pH, with uptake at pH 7.4 being four times greater than that at pH 4.0. The apparent synergic effects of lansoprazole are due to enhanced penetration of amoxycillin in gastric mucus and tissue by increasing intragastric pH and play an important role in the eradication of H. pylori.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2001

The effect of azithromycin and clarithromycin on ex vivo interleukin-8 (IL-8) release from whole blood and IL-8 production by human alveolar macrophages.

We investigated the effects of azithromycin and clarithromycin, two antibiotics that possess a broad spectrum of antimicrobial activity (including antimycobacterial activity), on interleukin-8 (IL-8) release from human whole blood leucocytes and lung macrophages. Ex vivo stimulation of leukocytes with either of the antibiotics (0.04-40 mg/L) significantly increased IL-8 secretion. Incubation of alveolar macrophages with different concentrations of azithromycin or clarithromycin modified IL-8 production: it increased at a drug concentration of 4 mg/L and decreased at concentration of 400 mg/L. Our findings suggest that azithromycin and clarithromycin may alter IL-8 production, thus enhancing the clinical effectiveness of these antibiotics.

Analysis of Variance↗
PubMed2001

Efficacy of azithromycin, clarithromycin and beta-lactam agents against experimentally induced bronchopneumonia caused by Haemophilus influenzae in mice.

Azithromycin is an azalide with potent activity against Haemophilus influenzae including ampicillin-resistant strains. We evaluated the efficacy of azithromycin, clarithromycin and three beta -lactams when used for 1 day only and for 3 days for the treatment of a murine model of bronchopneumonia, using three strains of H. influenzae, two of which were ampicillin resistant. MICs of azithromycin (1-2 mg/L) and clarithromycin (4-8 mg/L) were similar for the three strains. The MICs of cefdinir and cefcapene for beta-lactamase-negative ampicillin-resistant (BLNAR) H. influenzae were 32 times higher than those for beta-lactamase-positive ampicillin-resistant and ampicillin-susceptible strains. The viable counts in the infected tissues of azithromycin-treated mice with bronchopneumonia caused by the susceptible strain TUM8, beta-lactamase-positive strain TUH36 and BLNAR strain TUH267 were less than the counts obtained with the other antibiotics used, irrespective of MIC. At a dose of 50 mg/kg, the area under the concentration curve and the half-life of azithromycin in the lungs were respectively three times higher and six times longer than those of clarithromycin. Our results indicate that azithromycin may be useful for both ampicillin-susceptible and ampicillin-resistant bronchopneumonial infections caused by H. influenzae.

Animals↗
PubMed2002

Resistance of Helicobacter pylori isolated in Israel to metronidazole, clarithromycin, tetracycline, amoxicillin and cefixime.

The resistance of Helicobacter pylori isolated in Israel to metronidazole, clarithromycin, tetracycline, amoxicillin and cefixime was tested in 138 isolates, including 28 from treatment failures. No resistance to tetracycline was detected. Resistance to amoxicillin was found in one isolate (MIC = 1.5 mg/L) from an untreated patient, and resistance to cefixime in two isolates from each group (P = 0.18). Resistance to metronidazole and clarithromycin was much higher in the isolates from treated than from untreated patients: 60.7% and 38.2% for metronidazole (MIC >or= 8 mg/L) (P = 0.03); 46.4% and 8.2% for clarithromycin (MIC >or= 2 mg/L) (P < 0.001). Therapeutic outcome would benefit from susceptibility testing, especially after treatment failure.

Amoxicillin↗
PubMed2007

Clarithromycin alone and in combination with ceftriaxone inhibits the production of pneumolysin by both macrolide-susceptible and macrolide-resistant strains of Streptococcus pneumoniae.

OBJECTIVES: To investigate the effects of clarithromycin (0.01-0.5 mg/L) alone or in combination with ceftriaxone (0.1 and 0.25 mg/L) on pneumolysin production by both macrolide-susceptible and -resistant [2 erm(B) positive and 2 mef(A) positive] strains of Streptococcus pneumoniae. METHODS: The bacteria were cultured for 6 h at 37 degrees C/5% CO(2) in tryptone soy broth, washed, enumerated and resuspended to 0.5-3 x 10(8) cfu/mL in tissue culture medium, RPMI 1640. After 16 h of incubation at 37 degrees C / 5% CO(2), pneumolysin was assayed in the bacteria-free supernatants, as well as in lysates, using a functional assay based on the influx of calcium into human neutrophils. RESULTS: Exposure of not only macrolide-susceptible strains, but also the macrolide-resistant strains, of S. pneumoniae to sub-MICs of clarithromycin resulted in dose-related inhibition of the pneumolysin production, whereas production of the toxin was unaffected by ceftriaxone. CONCLUSIONS: These observations demonstrate that even in the setting of macrolide resistance the production of pneumolysin, a key virulence factor of the pneumococcus, is attenuated by exposure of this microbial pathogen to clarithromycin.

Anti-Bacterial Agents↗
PubMed1999

Oral rifampin plus azithromycin or clarithromycin to treat osteomyelitis in rabbits.

A rabbit model for Staphylococcus aureus osteomyelitis was used to compare 28-day combination antibiotic therapy using oral rifampin (40 mg/kg, twice daily) plus oral azithromycin (50 mg/kg, once per day), oral clarithromycin (80 mg/kg, twice daily), or parenteral nafcillin (30 mg/kg, four times daily). The left tibial metaphysis of New Zealand White rabbits was infected with Staphylococcus aureus. Grades 3 to 4 osteomyelitis (according to the Cierny-Mader classification system) development in the rabbits was confirmed radiographically. After antibiotic therapy regimens of 28 days, all tibias from controls that were infected but left untreated (n = 10) revealed positive cultures for Staphylococcus aureus at a mean concentration of 2.8 x 10(4) colony forming units/g bone. The rifampin plus clarithromycin (n = 15) and rifampin plus azithromycin (n = 15) groups showed significantly lower percentages of positive Staphylococcus aureus infection (20% and 13.3%, respectively) and bacterial concentrations (3.5 x 10(1) and 1.75 x 10(1) colony forming units/g bone, respectively). The osteomyelitic tibias of the nafcillin plus rifampin treated group (n = 7) showed no detectable Staphylococcus aureus infection (significantly lower than controls). The differences observed for bone bacterial concentrations and sterilization percentages between the antibiotic treated groups were not statistically significant. Although fluoroquinolones (including ofloxacin and ciprofloxacin) are the agents usually prescribed with rifampin, increasing resistance has been observed. Although macrolides traditionally are not used in the treatment of osteomyelitis, the results of this study indicate that azithromycin and clarithromycin may be attractive partners for rifampin for the treatment of Staphylococcus aureus osteomyelitis in humans.

Administration, Oral↗
PubMed1993

Clarithromycin for the eradication of Helicobacter pylori.

Helicobacter pylori infection has proven to be extraordinarily difficult to eradicate. Antimicrobial monotherapies have been particularly disappointing, with most eradication rates in the range of 0-15%. Clarithromycin has potential advantages over other macrolides to which H. pylori is susceptible because of its acid stability and solubility at low pH. We evaluated clarithromycin therapy (250 mg four times daily for 14 days) in 12 H. pylori-infected patients. The 13C-urea breath test was used to evaluate the effectiveness of therapy. Eradication was defined as a negative urea breath test 4-6 weeks after the end of treatment. Suppression of H. pylori was demonstrated in 11 of 12 patients (92%) by a negative urea breath test 2 days after start of treatment. H. pylori was eradicated in five (42%) of 12 patients. Adverse events were intermittent and mild. Clarithromycin is the first antimicrobial agent that appears to offer promise as monotherapy for the eradication of H. pylori.

Adolescent↗
PubMed1995

Eradication of Helicobacter pylori with lansoprazole and clarithromycin in gastric ulcer patients.

This study attempted to determine the efficacy of lansoprazole plus clarithromycin therapy in the eradication of Helicobacter pylori in gastric ulcer patients. The influence of H. pylori eradication on healing and relapse of ulcers was also studied. Thirty-nine patients received either lansoprazole 30 mg daily for 8 weeks (group 1) or clarithromycin 200 mg twice daily for 2 weeks and lansoprazole 30 mg daily for 8 weeks (group 2). Before treatment, H. pylori status was evaluated by a rapid urease test and histologic examination. H. pylori clearance and eradication were evaluated by a rapid urease test, polymerase chain reaction, and a [13C]urea breath test. Clearance of H. pylori was 0% in group 1 and was 33% in group 2. Eradication of H. pylori was 0% in group 1 and 21% in group 2. Although all five ulcers were healed in patients with H. pylori eradication, ulcers were not healed in the five patients without eradication. Relapse of ulcer was observed in three patients in whom eradication had failed. In this study, for H. pylori-positive gastric ulcer patients, better results were obtained when lansoprazole plus clarithromycin therapy was used, and H. pylori eradication was achieved.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Mycoplasma pneumoniae and Chlamydia pneumoniae in pediatric community-acquired pneumonia: comparative efficacy and safety of clarithromycin vs. erythromycin ethylsuccinate.

We evaluated 260 previously healthy children ages 3 through 12 years who had clinical signs and symptoms of pneumonia, radiographically confirmed. Patients were randomized 1:1 to a 10-day course of either clarithromycin suspension 15 mg/kg/day divided twice a day or erythromycin suspension 40 mg/kg/day divided twice a day or three times a day. Evidence of infection with Chlamydia pneumoniae was detected in 28% (74) of patients: 13% (34) by nasopharyngeal culture and 18% (48) by serology with the microimmunofluorescence assay. Evidence of infection with Mycoplasma pneumoniae was detected in 27% (69) of patients: 20% (53) by nasopharyngeal culture or polymerase chain reaction and 17% (44) by serology with the use of enzyme-linked immunosorbent assay. Serologic confirmation of infection was observed in 23% (8) and 53% (28) of patients with bacteriologically detected C. pneumoniae and M. pneumoniae, respectively. Treatment with clarithromycin vs. erythromycin, respectively, yielded the following outcomes: clinical success 98% (121 of 124) vs. 95% (105 of 110); radiologic success 98% (109 of 111) vs. 94% (92 of 110); and eradication by pathogen, C. pneumoniae 79% (15 of 19) vs. 86% (12 of 14) and M. pneumoniae 100% (9 of 9) vs. 100% (4 of 4). Adverse events were primarily gastrointestinal occurring in almost one-fourth of patients in both groups, and were mild to moderate in severity. Clarithromycin and erythromycin were similarly effective and safe for the treatment of radiographically proved, community-acquired pneumonia in children older than 2 years old.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1994

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

BACKGROUND: 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. METHODS: 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. RESULTS: Eradication was achieved in 26 patients (72%). The treatment was well tolerated with only 4 (11%) of the patients having significant side-effects. CONCLUSION: 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.

Adult↗
PubMed2004

Primary Helicobacter pylori resistance to metronidazole and clarithromycin in the Finnish population.

AIM: To systematically determine Helicobacter pylori primary antimicrobial resistance in Finland and the associated demographic and clinical features. METHODS: A total of 342 adult patients referred for gastroscopy at 23 centres in different parts of Finland and positive for the rapid biopsy urease test were recruited. Clinical and demographic data were collected via a structured questionnaire. Patients with positive H. pylori culture and successful antibiotic sensitivity determination by the E-test method (n = 292) were included in the present analysis. RESULTS: The study population consisted of 134 men and 158 women, mean age 56 years (95% CI, 55-58 years). Resistance to metronidazole was 38% (110 of 292) and to clarithromycin 2% (seven of 292). Resistance to metronidazole was higher in women than in men (48% vs. 25%, P < 0.001). Previous use of antibiotics for gynaecological infections predicted metronidazole resistance (P = 0.01), and previous use of antibiotics for respiratory (P = 0.02) and dental infections (P = 0.02) the clarithromycin resistance. We observed no major geographical variations in metronidazole resistance. CONCLUSIONS: The primary metronidazole resistance of H. pylori was 38% and was common in women previously treated for gynaecological infections. Primary clarithromycin resistance was uncommon (2%) and may associate with previous dental and respiratory infections.

Adolescent↗
PubMed1996

Triple therapy with lansoprazole, clarithromycin, and amoxicillin for the cure of Helicobacter pylori infection: a short report.

BACKGROUND: Given the therapeutic potential of proton pump inhibitor-based triple therapy for successful cure of Helicobacter pylori infection, we evaluated the efficacy and safety of lansoprazole with clarithromycin and amoxicillin in an open-label, single-center study. MATERIALS AND METHODS: H. pylori-positive patients self-administered lansoprazole, 30 mg; clarithromycin, 500 mg; and amoxicillin, 1 gm bid for 14 days. Patients were assessed pretreatment, at which time the presence of H. pylori was documented by rapid urease test, culture, or histology, following study drug administration (week 2) for a brief evaluation only, and at least 4 weeks posttreatment (week 6), which included endoscopy with collection of biopsy specimens for culture and histology testing. RESULTS: Primary clarithromycin and metronidazole resistance were observed in 6% (2 of 30) and 43% (13 of 30) of study patients, respectively. One month after the end of therapy, H. pylori infection was cured in 23 of 25 patients (92%; 95% confidence interval, 74%-99%). The triple-therapy regimen was well-tolerated; 17% of patients (5 of 30) reported mild to moderate adverse effects during the treatment period. CONCLUSION: A 2-week, triple-drug combination of lansoprazole, clarithoromycin, and amoxicillin is highly effective for cure of H. pylori infection. Additionally, the triple-drug combination was well-tolerated by patients infected with H. pylori.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1997

Ranitidine bismuth citrate with clarithromycin for the eradication of Helicobacter pylori and for ulcer healing.

BACKGROUND: In a pilot study, ranitidine bismuth citrate (RBC; Pylorid, Tritec) in coprescription with clarithromycin achieved a Helicobacter pylori eradication rate (based on 13C urea breath test alone) of 83%. The aim of the current study was to validate this finding by using three diagnostic tests and a larger group of H. pylori-positive patients with active duodenal ulcer. METHODS: In a blinded study, 95 patients were given either 4 weeks of treatment with RBC, 400 mg bid, alone (RBC400, n = 31) or RBC, 400 mg bid or 800 mg bid, in coprescription with clarithromycin, 250 mg qid for 14 days, followed by 14 days of RBC, 400 mg bid, alone (RBC400 + CLAR and RBC800 + CLAR, respectively; n = 32 for each). Rates of ulcer healing at week 4 and of H. pylori eradication (assessed by antral and corpus urease tests and histology and by 13C urea breath test) at week 8 were compared, together with the incidence of adverse events. RESULTS: All three regimens were effective at duodenal ulcer healing and were tolerated well. The coprescription regimens gave significantly higher observed H. pylori eradication rates (82% and 74% for RBC400 + CLAR and RBC800 + CLAR) compared with RBC400 (0%; p < .001). CONCLUSIONS: RBC in dual therapy with clarithromycin provides excellent H. pylori eradication therapy and is an effective duodenal ulcer healing drug.

Adult↗
PubMed2006

Comparison of amoxicillin-metronidazole plus famotidine or lansoprazole for amoxicillin-clarithromycin-proton pump inhibitor treatment failures for Helicobacter pylori infection.

BACKGROUND: Proton pump inhibitor-amoxicillin-metronidazole is recommended as second-line Helicobacter pylori therapy in Japan. The authors assessed the efficacy and safety of second-line eradication using the H2-receptor antagonist famotidine as a substitute for proton pump inhibitor. MATERIALS AND METHODS: Sixty-one patients who failed in first-line H. pylori eradication using proton pump inhibitor-clarithromycin-amoxicillin were randomly assigned to either second-line therapy including metronidazole: a 7-day course of lansoprazole 30 mg, amoxicillin 750 mg, and metronidazole 250 mg, b.i.d. (lansoprazole group); or a 7-day course of famotidine 40 mg, amoxicillin 750 mg, and metronidazole 250 mg, b.i.d. (famotidine group). Eradication was assessed for each group at least 4 weeks after completing eradication therapy. Drug susceptibility test was performed using 57 strains in pretreatment to clarithromycin, metronidazole, and amoxicillin. RESULTS: Prior to second-line H. pylori eradication, the rate of resistance to clarithromycin was high at 84% (48/57). Similarly, resistance to metronidazole was low at 5.3% (3/57); however, no amoxicillin-resistant strains were found. The eradication rates for both lansoprazole and famotidine treatment groups were high at 97% (29/30) and 94% (29/31), respectively. CONCLUSIONS: Famotidine treatment including metronidazole-amoxicillin as second-line therapy provided a high eradication rate similar to lansoprazole therapy. Famotidine is therefore expected to serve as a useful H. pylori eradication regimen in patients with proton pump inhibitor allergy, an economic benefit in terms of reduced health-care costs is also anticipated.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1998

Dual therapy using a double dose of lansoprazole with amoxicillin versus triple therapy using a double dose of lansoprazole, amoxicillin, and clarithromycin to eradicate Helicobacter pylori infection: results of a prospective randomized open study.

OBJECTIVES: The eradication of Helicobacter pylori is recommended in duodenal ulcer disease. The aim of this randomized open trial was to evaluate and compare H. pylori eradication and safety after a dual therapy consisting of lansoprazole (30 mg b.i.d.) and amoxicillin (1 g b.i.d.) versus a triple therapy consisting of lansoprazole (30 mg b.i.d.), amoxicillin (1 g b.i.d.), and clarithromycin (500 mg b.i.d.) administered from day 1 to day 14. METHODS: All patients with an ulcer received lansoprazole (30 mg) from day 15 to day 28. H. pylori status was determined from antral biopsies using histology, culture, and polymerase chain reaction (PCR) upon inclusion and 1-3 months after the end of the treatment. RESULTS: Of the 50 patients included in the study, five did not adhere to the protocol. H. pylori eradication was obtained in 37.5% of the patients receiving lansoprazole-amoxicillin (n = 9/24) and in 95.2% of the patients receiving lansoprazole-amoxicillin-clarithromycin (n = 20/21, p < 0.0002). Minor side effects appeared in 8.3% of the cases during dual therapy (n = 2/24) and in 52% during triple therapy (n = 13/22, p < 0.001). These side effects consisted mainly of diarrhea and a metallic taste. CONCLUSION: Concomitant administration of double doses of lansoprazole with amoxicillin and clarithromycin is very efficacious against H. pylori infection compared with dual therapy.

2-Pyridinylmethylsulfinylbenzimidazoles↗