Search

Objectives: We evaluated a new approach for the rapid detection of clarithromycin resistance in Helicobacter pylori, based on PCR and denaturing HPLC (DHPLC)., Methods: A 180 bp fragment of the 23S rRNA gene was amplified using DNA from 81 clinical H. pylori isolates (51 isolates were shown to be resistant to clarithromycin by Etest), and, directly, from 101 gastric biopsies from patients with digestive diseases, who were infected with H. pylori as assessed by a 13C-urea breath test, histology and/or culture. DHPLC was used to detect mutations in all the PCR products., Results: DHPLC profiles for the 30 susceptible isolates all showed homoduplex peaks; the resistant isolates consistently generated heteroduplex peaks that were easily distinguishable from the wild-type H. pylori reference strain. Sequencing revealed point mutations in all the resistant isolates. Overall, five different mutations were detected. Four of these mutations (A2142G, A2142C, A2143G and T2182C) are known to be associated with clarithromycin resistance; the remaining mutation (C2195T) has not been previously described. This novel single-base substitution was found in combination with the common mutation A2143G. Of the biopsies tested, 25 specimens generated heteroduplexes due to sequence alterations (mutation A2142G, A2142C or A2143G). In one of these specimens, A2143G was found together with the novel mutation T2221C; in another, a mixture of wild-type and mutant (A2143G) sequences was detected. For 20 culture-positive out of the 25 biopsies DHPLC results confirmed the presence of clarithromycin resistance., Conclusions: Our results suggest that the PCR-DHPLC assay is a valid tool for rapid assessment of clarithromycin resistance in H. pylori and that in the future it could be used directly on biopsy specimens, avoiding the need for culture-based methods.

Current treatment for Helicobacter pylori infections generally includes two or more antimicrobials (amoxicillin, clarithromycin, nitroimidazoles, tetracycline, etc.), but treatment fails in 10-20% of all cases, often because of drug resistance. Levofloxacin has been proposed as an alternative for these refractory infections. We examined 67 H. pylori isolates from patients unsuccessfully treated with amoxicillin, clarithromycin, metronidazole and levofloxacin. Minimum inhibitory concentrations determined with the epsilometer test revealed clarithromycin and metronidazole resistance in 91 and 82.1% of the isolates, respectively; 52 (77.6%) were resistant to both drugs. All 67 isolates were susceptible to amoxicillin and tetracycline. Fifty-two isolates had levofloxacin MICs of 0.01-2 mg/l; the remaining 15 (22.4%), all clarithromycin- and metronidazole-resistant, had MICs >/= 8 mg/l. Levofloxacin may be an option for refractory H. pylori infections, but the choice should be based on in vitro susceptibility data, and physicians should consider local resistance patterns when treating these infections empirically.

Goals: To compare high-dose versus low-dose clarithromycin in 1-week triple therapy including rabeprazole and levofloxacin., Background: Regimens containing rabeprazole and levofloxacin have proved to be effective against H. pylori infection., Study: One-hundred H. pylori-positive patients were randomly assigned to one of the following 1-week regimens: rabeprazole 20 mg o.d. plus levofloxacin 500 mg o.d. and clarithromycin 250 mg b.d. (RLC-1 group); rabeprazole 20 mg o.d. plus levofloxacin 500 mg o.d. and clarithromycin 500 mg b.d. (RLC-2 group). H. pylori status was assessed at entry and after the treatment. Patients who experienced treatment failure underwent antibiotic susceptibility testing., Results: Forty-two patients in RLC-1 group (both PP and ITT analysis: 84%; 95%CI: 71-93%) and 47 in RLC2 group (both PP and ITT analysis: 94%; 95% CI: 83-98%) became H. pylori negative. Clarithromycin resistance was detected in all of 8 (100%) RLC-1 failures and in 1 out of 3 (33%) RLC-2 failures. Side effects occurred in 8% of patients in RLC-1 group and in 12% in RLC-2., Conclusions: Regimens tested are competitive with other PPI-based treatments. One-week triple therapy containing rabeprazole plus, levofloxacin, and high-dose clarithromycin yielded a higher eradicating rate than the one containing low-dose clarithromycin and may be considered as a first-line therapy option.

Background: Helicobacter pylori eradication therapies do not achieve 100% success rates. Antibiotic resistant strains are among the major causes of failure. Current recommendations concerning the management of treatment failures are not fully clear., Aim: To evaluate the efficacy of a multi-step therapeutic strategy in a large group of infected patients., Methods: A total of 2606 H. pylori-positive patients were administered tinidazole, clarithromycin and a proton pump inhibitor for 1 week. Patients with continuing infection were then given a second 1-week course of amoxycillin, clarithromycin and ranitidine bismuth citrate. Patients still infected after the second course underwent upper gastrointestinal endoscopy with H. pylori culture, and then received a 1-week quadruple proton pump inhibitor-bismuth based scheme established on H. pylori antibiotic sensitivity., Results: After the first step, eradication was achieved in 2063 out of 2413 patients [86% per protocol analysis (PP); 79% intention-to-treat analysis (ITT)]. First-step failures (350 out of 2413; 14.5% PP) showed second-step eradication rates of 82% (271 out of 329 patients, PP; 77% ITT). The specific quadruple therapy for second-step failures (58 out of 329, 18% PP) achieved 77% (30 out of 39 patients, PP) or 52% (ITT) success. This algorithm led to overall eradication rates of 99% (PP) or 91% (ITT)., Conclusions: This multi-step strategy succeeded in a high percentage of H. pylori infected patients. Given the lack of precise guidelines on treatment failures, assessing H. pylori sensitivity to antibiotics only after failure of the second treatment could be suggested in clinical practice.