Quinolone-based first, second and third-line therapies for Helicobacter pylori

Second line therapy for Helicobacter pylori eradication: state of art

Helicobacter pylori (H. pylori) is a Gram negative spiraliform bacterium who colonizes the human stomach. It is the most common cause of chronic gastritis, peptic ulcer, and gastric carcinoma. The eradication therapy is based on the combination of a proton pump inhibitor and several antibiotics such as amoxicillin, metronidazole, clarithromycin, levofloxacin or tetracycline. The most commonly used regimens for eradication in the first line are triple, sequential and concomitant therapy, despite the last European Guidelines suggesting a quadruple therapy already at the first attempt in areas with high resistance rates. However, the rise in antibiotic resistance is the main reason for a marked increase in first-line therapy failure. Clarithromycin resistancea , is especially acknowledged as the most important event resulting in failure. Up to 20% of patients are intended not to eradicate, therefore they will need a second line therapy. Currently, the most used rescue regimens are levofloxacin-based triple therapy and bismuth-containing quadruple therapy, despite guidelines suggesting to use a combination of antibiotics that have not been included in previous treatments. Nitazoxanide is a novel antibiotic with promising results. Additionally, an interesting field worth of investigation is the antibiotic susceptibility based approach, which could help to choose antibiotics with confirmed effectiveness in vitro. Analysis of antibiotic resistance may be performed by both bacterial culture and molecular biology techniques, able to detect point mutations conferring resistance. This is a particularly interesting approach, since it may personalize the therapy, thus optimizing the regimen and maximizing the probability of success.

Helicobacter pylori DNA isolation in the stool: an essential pre-requisite for bacterial noninvasive molecular analysis

PURPOSE

Real-time polymerase chain reaction (RT-PCR) is a widely used technique for bacterial and viral infection diagnosis. Herein, we report our preliminary experience in retrieving H. pylori genetic sequences in stools and analyzing genotypic clarithromycin resistance by RT-PCR (noninvasive), with the aim of comparing this procedure with that performed on biopsy samples (invasive).

MATERIALS AND METHODS

After 'in vitro' demonstration of H. pylori DNA detection from pure and stool-mixed bacteria, 52 consecutive patients at the first diagnosis of infection were investigated. DNA was extracted from biopsy tissue and stool samples (THD^® Fecal Test, Italy). RT-PCR was performed to detect 23S rRNA encoding bacterial subunit gene and search A2143G, A2142C, A2142G point mutations for clarithromycin resistance assessment.

RESULTS

RT-PCR showed H. pylori positive DNA in all infected patients with full concordance between tissue and stool detection (100%). We found A2143G mutation in 10 (19.2%), A2142G in 4 (7.7%) and A2142C in 5 (9.6%) patients; there was a full agreement between biopsy and fecal samples. A2143G was found in all the four A2142G positive cases and in three out of the five A2142C positive strains. Overall clarithromycin resistance rate in our series was 23%.

CONCLUSIONS

Despite the need of confirmation on large sample, stool RT-PCR analysis could represent a feasible tool to detect H. pylori DNA sequences and antibiotic resistance point mutations. As compared to tissue molecular analysis, this technique is noninvasive, with potential advantages such as improvement of patient compliance, reduction of diagnostic procedure time/cost and improvement of therapeutic outcome.

Role of concomitant therapy for Helicobacter pylori eradication: A technical note

We read with interest the recent meta-analysis by Lin et al who evaluated the effectiveness of concomitant regimen for Helicobacter pylori (H. pylori) in Chinese regions. They found that 7-d concomitant regimen is undoubtedly superior to 7-d triple therapy (91.2% vs 77.9%, P < 0.0001). However, it is a common belief that a triple therapy lasting 7 d should be definitively removed from the clinical practice for its ineffectiveness. Only its prolongation to 14 d may give satisfactory success rate. Thus, the assessment of an old and outdated treatment versus a more recent and successful one does not seem to bring novel and useful information. Moreover, a 7-d duration has not been ascertained for concomitant regimen, as main guidelines recommend a 10-d schedule for this scheme. Therefore, only studies comparing 10-d concomitant versus 14-d triple seem to be appropriate according to current Guidelines and would clarify which regimen is the most suitable worldwide. Additionally, in this meta-analysis concomitant and sequential therapy showed similar performances, despite it is common opinion that sequential is more prone than concomitant therapy to fail when metronidazole resistance occurs, and China is characterized by high rate of resistance to this antibiotic. None of the included studies evaluated a priori antibiotic resistances, and the lack of this detail hampers the unveiling of this apparent contradiction. In conclusion, the lack of the evaluation of the quality of included trials as well as their high heterogeneity constitute a burdensome limit to draw solid conclusions in this meta-analysis. On the bases of these considerations and the low number of examined trials, we believe that further studies and the knowledge of antibiotic resistances will support with high quality evidence which is the best regimen and its optimal duration.