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PubMed2002

Assessment of clarithromycin-resistant Helicobacter pylori among patients in Shanghai and Guangzhou, China, by primer-mismatch PCR.

Of 96 Helicobacter pylori isolates from patients in Shanghai and Guangzhou, China, 5 had the A2143G 23S rRNA mutation as determined by primer-mismatch PCR and were resistant to clarithromycin by the E-test. The remaining isolates were primer-mismatch PCR negative and susceptible to clarithromycin. The conclusion is that the prevalence of clarithromycin-resistant H. pylori isolates among these Chinese patients is 5%.

Anti-Bacterial Agents↗
PubMed2003

Clarithromycin resistance among Helicobacter pylori strains isolated from children: prevalence and study of mechanism of resistance by PCR-restriction fragment length polymorphism analysis.

Clarithromycin and metronidazole resistance was 29.1 and 23.9%, respectively, in 96 Helicobacter pylori strains obtained from pediatric patients. No resistance to amoxicillin was observed. Resistance according to patients' ages to clarithromycin and metronidazole was 45.4 and 18.2% in 22 patients from 4 to 8 years old, 30.2 and 20.7% in 53 patients from 9 to 13 years old, and 9.5 and 38.1% in 21 patients from 14 to 18 years old, respectively. The A2143G mutation was the most prevalent (82.1%) among clarithromycin-resistant strains.

Anti-Bacterial Agents↗
PubMed2006

Comparison of 1 and 2 weeks of omeprazole, amoxicillin and clarithromycin treatment for Helicobacter pylori eradication: the HYPER Study.

BACKGROUND: Triple therapy is recommended for Helicobacter pylori eradication, yet consensus on the duration of treatment is lacking. AIM: To compare the efficacy and safety of 1- and 2-week regimens of omeprazole, amoxicillin and clarithromycin in a large, multicentre, double-blind and randomised study. METHODS: A total of 909 H pylori-positive patients with duodenal ulcer, enrolled in 81 endoscopy units in Italy, were randomised to receive omeprazole, amoxicillin and clarithromycin for either 1 week (OAC1W) or 2 weeks (OAC2W) or omeprazole and amoxicillin for 2 weeks. H pylori eradication was assessed by histological examination and carbon-13 urea breath test 4 weeks after treatment. RESULTS: Both the intention-to-treat (ITT; n = 907) and per protocol (PP; n = 661) analyses showed no significant differences between the eradication rates of OAC1W (ITT 79.7%; PP 83.6%) and OAC2W (ITT 81.7%; PP 84.9%; ITT p = 0.53; PP p = 0.71). Both triple omeprazole, amoxicillin and clarithromycin regimens gave significantly higher eradication rates compared with omeprazole and amoxicillin treatment (ITT 44.6%; PP 42.8%; p<0.001). Poor compliance was reported in 18.6%, 17.3% and 15.1% (p = 0.51) of patients for OAC2W, OAC1W and omeprazole and amoxicillin, respectively. Adverse events occurred in 9.9% and 9.6% (p = 0.88) of patients for OAC2W and OAC1W, respectively, and in 5.9% for omeprazole and amoxicillin (p = 0.11). CONCLUSIONS: 1-week and 2-week triple treatments for H pylori eradication are similar in terms of efficacy, safety and patient compliance.

Adolescent↗
PubMed1997

Ranitidine bismuth citrate with clarithromycin for the treatment of duodenal ulcer.

BACKGROUND/AIMS: To investigate the effect of the new Helicobacter pylori eradication regimen, ranitidine bismuth citrate (RBC) and clarithromycin (CLAR) dual therapy, on duodenal ulcer healing and absence of ulcer recurrence during 24 weeks follow up (overall success). METHODS: Two hundred and thirty two H pylori positive patients with active duodenal ulcer received four weeks treatment with RBC 400 mg twice daily alone (RBC400) (n = 82), or RBC 400 or 800 mg twice daily co-prescribed with clarithromycin 250 mg four times daily for 14 days, followed by 14 days of RBC 400 mg twice daily alone (RBC400+CLAR and RBC 800+CLAR, respectively, n = 75 for each). RESULTS: The co-prescription regimens gave high H pylori eradication rates determined using two tests (CLOtest and 13C-urea breath test) for the presence of the organism. These rates were 92% and 81% for RBC400+CLAR (n = 62) and RBC800+CLAR (n = 63) respectively, compared with 2% for RBC400 (n = 66) (p < 0.001). With respect to overall success as estimated by life table analysis, RBC400+CLAR (89%) and RBC800+CLAR (87%) were significantly more effective than RBC400 alone (51%) (p < 0.001). All regimens were safe and well tolerated. Trough plasma bismuth concentrations at week 4 were low (treatment medians less than 6.6 ng bismuth/ml). CONCLUSIONS: Ranitidine bismuth citrate is a well tolerated and efficacious ulcer healing drug which, when co-prescribed with clarithromycin, affords effective H pylori eradication therapy and prevents ulcer relapse in most patients with duodenal ulcer.

Adolescent↗
PubMed2005

Irreversible sensorineural hearing loss due to clarithromycin.

Clarithromycin is a commonly used advanced generation macrolide. This case study reviews a case of an 81 year old woman who developed sensorineural deafness in the right ear after the start of low dose oral clarithromycin for an infective exacerbation of chronic obstructive pulmonary disease. Despite cessation of this drug after only three days, the sensorineural deafness was found to be irreversible. Reversible sensorineural deafness secondary to macrolides has previously been described and evidence in the literature shows that a dose related phenomenon occurs. Research has indicated that transient dysfunction of the outer hair cells could be the possible mechanism. In this case, however, the patient experienced an irreversible sensorineural deafness associated with the start of low dose oral clarithromycin. This is a side effect profile that has not previously been reported.

Aged↗
PubMed2000

Pathophysiology of antibiotic resistance: clarithromycin.

Resistance of Helicobacter pylori to antibiotics ranges from 3% to 10% and may exceed these levels in some countries. The pathophysiology of clarithromycin resistance is reviewed, including the mode of action by which the antibiotic inhibits protein synthesis and the mechanism of resistance, which involves a mutation at position 2142 or 2143 in the V loop domain of the 23SrRNA genes. Mutations of A2142G confer a higher minimum inhibitory concentration than mutations of A2143G. The former demonstrate cross-resistance to macrolide, lincosamide and streptogramin antibiotics, whereas the latter are susceptible to streptogramin B. In vitro mutagenesis combined with natural transformation were used to create several types of clarithromycin-resistant mutants. H pylori strains with A2142G and A2143G mutations had a higher growth rate than those with A2142C, A2143 or A2142T mutations. Data from this study indicate why clarithromycin-resistant clinical isolates of H pylori are more likely to have A2142G or A2143G mutations and only occassionally A2142C mutations.

Anti-Bacterial Agents↗
PubMedDate not supplied

Comparison of omeprazole, metronidazole and clarithromycin with omeprazole/amoxicillin dual-therapy for the cure of Helicobacter pylori infection.

In this randomized, multicenter trial, we evaluated the effectiveness and side effect profile of a modified omeprazole-based triple therapy to cure Helicobacter pylori infection. The control group consisted of patients treated with standard dual therapy comprising omeprazole and amoxicillin. One hundred and fifty-seven H. pylori infected patients with duodenal ulcers were randomly assigned to receive either a combination of omeprazole 10 mg, clarithromycin 250 mg and metronidazole 400 mg (OCM) given three times daily for 10 days (n = 81), or a combination of omeprazole 20 mg and amoxicillin 1 g (OA) given twice daily for 14 days (n = 76). Prior to treatment and after 2 and 6 weeks, gastric biopsies from the antrum and corpus were obtained for histology and H. pylori culture. H. pylori infection was cured in 97.4% after OCM and in 65.8% after OA in the per-protocol analysis (p < 0.001) (intention-to-treat analysis: 93.4% and 63.2%, respectively). H. pylori was successfully cultured in 122 patients (77%). The overall rate of metronidazole resistance was 19.7% (24/122), no primary resistance to clarithromycin or amoxicillin was found. In the OCM group, all patients infected with metronidazole-sensitive H. pylori strains (n = 51) and those infected with strains of unknown susceptibility to metronidazole (n = 14) were cured (100%), while 77% (10/13) of those harboring metronidazole-resistant strains were cured of the infection (p = 0.36). Side effects leading to premature termination of treatment occurred in 2.5% of the patients in the OCM group and in 1.4% of the OA group. We conclude that combined treatment with omeprazole, clarithromycin and a higher dose of metronidazole is highly effective in curing H. pylori infection, and that this regimen remains very effective in the presence of metronidazole-resistant strains.

Adolescent↗
PubMed2004

Differential efficacy of clarithromycin in lung versus thigh infection models.

BACKGROUND: Differences in clarithromycin disposition and the resulting changes in bacterial density were studied using mouse lung and thigh infection models. METHODS: Clarithromycin activity was evaluated against seven Streptococcus pneumoniae isolates with efflux-mediated resistance in both murine lung and thigh infection models. Intrapulmonary disposition of clarithromycin was also studied. RESULTS: Consistent bacterial kill was observed in the lung model, whereas no drug effect was observed in the thigh model. CONCLUSION: These differences in bacterial density were supported by high concentrations observed in epithelial lining fluid as compared to serum.

Administration, Oral↗
PubMed1997

Effect of clarithromycin on lymphocytes in chronic respiratory Pseudomonas aeruginosa infection.

In a newly established murine model of chronic Pseudomonas aeruginosa respiratory infection mimicking diffuse panbronchiolitis (DPB), we investigated the effect of oral administration of clarithromycin on lymphocyte accumulation in the lung. Infection was produced by placement of a plastic tube precoated with P. aeruginosa in the bronchus. The number of bacteria on the tube was 6.25 +/- 0.22 log10 colony-forming units (cfu)/ml. Viable bacteria were constantly isolated at 10(5) to 10(6) cfu/specimen from the lungs for more than 1 yr. The histopathologic features resembled those of DPB consisting of massive accumulation of lymphocytes in the lung. The total number of pulmonary lymphocytes started to increase on Day 7, reaching a peak level within 12 d of intratracheal challenge. The number remained steady at that level for up to 120 d. There was also a steady fall in the CD4+/CD8+ ratio in the lungs, commencing on Day 7 and persisting to Day 120. A 10-d course of oral clarithromycin (10 mg/kg/d) from Day 7 resulted in a reduction of lymphocyte numbers to baseline level, although the dose did not influence the number of bacteria in the lungs. Treatment also increased the CD4+/CD8+ ratio to the baseline level from Day 7 to 17. Our results were similar to those detected in bronchoalveolar lavage fluid of patients with DPB and suggest that the therapeutic benefits of clarithromycin are due to its anti-inflammatory properties rather than antimicrobial effect.

Animals↗
PubMed2002

Progressive cholestatic liver disease associated with clarithromycin treatment.

The authors report a case of an acute toxic cholestatic reaction to clarithromycin, proven by liver biopsy, in a patient with comorbid diseases, prior exposure to erythromycin and ultimate death. No autopsy was performed. A 59-year-old woman with diabetes mellitus and chronic renal insufficiency received clarithromycin 500 mg twice daily for 3 days for acute maxillary sinusitis and then developed a rash and jaundice. She was hospitalized 11 days after stopping clarithromycin. Progressive cholestatic jaundice accompanied by oligo-anuric renal failure requiring hemodialysis ensued. Liver biopsy showed pure bilirubinostasis without parenchymal inflammation. On the 22nd hospital day, after clinical deterioration, she died from an apparent cardiopulmonary death. This is the first report in the literature of a fatality associated with a short-term, low (1 g) daily dose of drug-induced pure cholestasis, an entity not previously identified with severe drug-induced hepatotoxicity.

Anti-Bacterial Agents↗
PubMedDate not supplied

Enhanced effect of clarithromycin on neutrophil function in vitro.

An in vitro study was carried out to investigate the effect of clarithromycin, a new oral macrolide, on neutrophil reactive oxygen species generation and chemotaxis. It was found that neutrophil-generated O2-, H2O2 and OH. levels were significantly increased by clarithromycin at concentrations of 50 micrograms/ml (P < 0.05). The drug also significantly increased chemotaxis (P < 0.05). These results indicate that clarithromycin may enhance the activation of neutrophils in vivo.

Anti-Bacterial Agents↗
PubMedDate not supplied

Azithromycin compared with clarithromycin for the treatment of streptococcal pharyngitis in children.

The treatment of streptococcal pharyngitis with azithromycin (10 mg/kg orally once daily for 3 days) or clarithromycin (7.5 mg/kg orally twice daily for 10 days) was compared in a randomized observer-blind study carried out in 174 children with documented Streptococcus pyogenes infection. The observed cure rate 10 days after the beginning of treatment was 61/63 (96.8%) in the clarithromycin group and 71/74 (95.9%) in the azithromycin group. At days 17-20 the bacteriological eradication rate was 95.2% for clarithromycin and 94.6% for azithromycin. When children who did not complete treatment were included in the analysis the eradication rate was higher for azithromycin (93.6% compared with 82.9%; P < 0.05); the difference was due to better compliance with the azithromycin regimen.

Adolescent↗
PubMed1992

The new macrolide antibiotics: azithromycin, clarithromycin, dirithromycin, and roxithromycin.

OBJECTIVE: To review the chemistry, antimicrobial spectrum, pharmacokinetics, clinical trials, adverse effects, and drug interactions of four new macrolide antibiotics: azithromycin, clarithromycin, dirithromycin, and roxithromycin. DATA SOURCES: Information was obtained from comparative clinical trials, abstracts, conference proceedings, and review articles. Indexing terms included azithromycin, clarithromycin, dirithromycin, erythromycin, roxithromycin, and macrolide antibiotics. STUDY SELECTION: Emphasis was placed on comparative clinical trials involving the new macrolide antibiotics. DATA EXTRACTION: Data from human studies published in the English language were evaluated. Trials were assessed by sample size, macrolide dosage regimen, and therapeutic response. DATA SYNTHESIS: The erythromycins have gained widespread use in treating a variety of infections. Although they are effective, limitations include the need to administer four times a day and the intolerable adverse gastrointestinal effects. Four of the more extensively studied agents, azithromycin, clarithromycin, dirithromycin, and roxithromycin, are currently being studied in patients. Based on the studies to date, the newer macrolides may offer several advantages over erythromycin, including: (1) greater antimicrobial activity against certain organisms; (2) longer elimination half-life, thus allowing less frequent administration; and (3) lower incidence of adverse gastrointestinal effects. CONCLUSIONS: The new macrolide antibiotics appear to offer an improvement over erythromycin. Definitive conclusions about the role of these drugs should await completion of ongoing clinical studies.

Anti-Bacterial Agents↗
PubMedDate not supplied

Lovastatin-induced rhabdomyolysis possibly associated with clarithromycin and azithromycin.

OBJECTIVE: To describe two cases of rhabdomyolysis in patients taking lovastatin that were precipitated by the use of the newer macrolide antibiotics clarithromycin and azithromycin. CASE SUMMARIES: In each case, the patients were treated over 5 years with lovastatin and developed rhabdomyolysis that coincided with the completion of a prescribed regimen of a newer macrolide antibiotic. Following intravenous hydration and administration of bicarbonate, the patients' condition resolved without permanent' sequelae. DISCUSSION: Rhabdomyolysis is a clinical syndrome resulting from the destruction of skeletal muscle that may progress to renal failure Several drugs have been associated with rhabdomyolysis, including lovastatin, a hydroxymethylglutaryl-coenzyme A reductase inhibitor. Erythromycin is a macrolide antibiotic that may increase the risk of lovastatin-induced rhabdomyolysis. To our knowledge, these cases are the first published reports of lovastatin-induced rhabdomyolysis associated with azithromycin and clarithromycin. CONCLUSIONS: The risk of drug-induced rhabdomyolysis due to the potential interaction between lovastatin and azithromycin or clarithromycin should be considered before the concomitant use of these agents.

Aged↗
PubMed1998

Long term treatment with clarithromycin for cryptosporidiosis and emergence of drug resistant disseminated infection due to Mycobacterium avium: case report.

Macrolide resistance in disseminated Mycobacterium avium infection is of major concern in AIDS patients as these drugs represent the main component of combination therapy. Clarithromycin and azithromycin should not be used alone for the treatment and prophylaxis of the disease because of the risk of selecting resistant strains. We report the case of a clarithromycin resistant disseminated M. avium infection in an AIDS patient, acquired after long term monotherapy with clarithromycin for the treatment of cryptosporidiosis.

AIDS-Related Opportunistic Infections↗
PubMed2000

In vitro activity of clarithromycin against penicillin-susceptible and penicillin-resistant strains of Streptococcus pneumoniae in a pharmacodynamic simulation model.

Clarithromycin has shown enhanced activity against Streptococcus pneumoniae, but increased resistance to macrolides has been observed in recent years. Our aim was to investigate its activity against strains of S. pneumoniae with variable susceptibility to this antibiotic and to penicillin. We determined killing curves using the Centriprep-10 pharmacodynamic simulation model, which permits using varying antibiotic concentrations to mimic a pharmacokinetic human profile in serum (corresponding to an oral dose of 500 mg). Four strains of S. pneumoniae were tested. In susceptible strains, clarithromycin showed bactericidal activity (reductions of up to 2.97 log10 cfu/ml of the initial inoculum). In resistant strains, clarithromycin showed a bacteriostatic effect (<1 log10 cfu/ml reduction). Penicillin-susceptible strains showed higher reductions than penicillin-resistant strains. This effect is important owing to the high minimum inhibitory concentration (MIC) of one of the resistant strains (32 microg/ml). More studies are needed to explain this bacteriostatic activity.

Anti-Bacterial Agents↗
PubMed2002

An open, comparative pilot study of thiamphenicol glycinate hydrochloride vs clarithromycin in the treatment of acute lower respiratory tract infections due to Chlamydia pneumoniae.

The aim of this study was to evaluate the efficacy and tolerability of thiamphenicol glycinate hydrochloride (TGH) i.m. versus clarithromycin in acute lower respiratory infections due to Chlamydia pneumonia. 113 patients with suspected pneumonia were screened. 40 patients with IgM and/or IgA titers > or = 1:16 and/or IgG titers > or = 1:512 were assigned to 10 days of treatment with TGH 1500 mg daily or clarithromycin 1000 mg daily. 34 patients were considered a clinical success. 33 patients were a radiological success. 22 patients showed a decrease in IgG values. 3 patients had an increase in IgG values. Blood/urine values presented no clinically significant variations. Clinical efficacy was similar in both treatment groups. These are the first results confirming in vivo the recent in vitro evidence that TGH is effective against acute lower respiratory tract infections due to C. pneumoniae, thus representing an alternative therapy to clarithromycin.

Administration, Oral↗
PubMed2004

Serum bactericidal activity of gemifloxacin versus clarithromycin against Streptococcus pneumoniae with different susceptibility to quinolones.

The objective of this study was to determine serum bactericidal titers (SBT, the highest dilution of serum showing no growth) and the serum bactericidal activity (SBA, i.e. duration of SBT greater than 1:2) as well as the serum bactericidal rate of gemifloxacin and clarithromycin after single doses in healthy male volunteers against Streptococcus pneumoniae. Strains tested had various degrees of susceptibility to penicillin as well as different susceptibility to quinolones due to a different QRDR mutation pattern (parC, gyrA). Serum samples from volunteers (n = 12) who had received a single oral dose of either 320 mg gemifloxacin or 500 mg clarithromycin in an open-label crossover study were obtained over a 24-hour period. SBA was determined, using the microdilution method. SBA of wildtype strains for gemifloxacin ranged from 8.9 to 15.4 h (mean 12.6 h). For gemifloxacin, 2 strains with solitary gyrA mutation had an SBA from 4.5 to 4.7 h (median 4.5 h). One of the 2 strains with a single QRDR mutation in parC displayed an SBA of 4.5 h, comparable to the gyrA mutation strains, whereas the second strain had a nearly twice as long SBA of 8.9 h. Two strains with two mutations (parC and gyrA) did not display any SBA. For clarithromycin, the duration of SBA ranged from 11.3 to 15.5 h (mean 13.6 h) for 6 of the 12 strains with an MIC < or = 0.06 mg/L (no SBA was found for the remaining strains, with an MIC of 0.25 mg/L or higher). In conclusion, a correlation between individual serum concentrations and SBA was found for both antibiotics.

Administration, Oral↗