Gatifloxacin-based triple therapy as a third-line regimen for Helicobacter pylori eradication

Evidence based guidelines for the treatment of Helicobacter pylori infection in Korea 2020

Helicobacter pylori infection is one of the most common infectious diseases worldwide. H. pylori is responsible for substantial gastrointestinal morbidity with a high disease burden. Since the revision of the H. pylori Clinical Practice Guidelines in 2013 in Korea, the eradication rate of H. pylori has gradually decreased with the use of a clarithromycin based triple therapy. According to a nationwide randomized controlled study by the Korean College of Helicobacter and Upper Gastrointestinal Research released in 2018, the intention-to-treat eradication rate was only 63.9%, which was mostly due to increased antimicrobial resistance to clarithromycin. The clinical practice guidelines for treatment of H. pylori were updated based on evidence-based medicine from a meta-analysis conducted on a target group receiving the latest level of eradication therapy. The draft recommendations developed based on the meta-analysis were finalized after expert consensus on three recommendations regarding the indication for treatment and eight recommendations on the treatment itself. These guidelines were designed to provide clinical evidence for the treatment of H. pylori to patients, nurses, medical school students, policymakers, and clinicians. These may differ from current medical insurance standards, and will be revised if more evidence emerges in the future.

Sitafloxacin for Third-Line Helicobacter pylori Eradication: A Systematic Review

BACKGROUND AND AIM

Sitafloxacin-based therapy is a potent candidate for third-line Helicobacter pylori eradication treatment. In this systematic review, we summarise current reports with sitafloxacin-based therapy as a third-line treatment.

METHODS

Clinical studies were systematically searched using PubMed, Cochrane library, Web of Science, and the Igaku-Chuo-Zasshi database. We combined data from clinical studies using a random-effects model and calculated pooled event rates, 95% confidence intervals (CIs), and the pooled odds ratio (OR).

RESULTS

We included twelve clinical studies in the present systematic review. The mean eradication rate for 7-day regimens of either PPI (proton pump inhibitor) or vonoprazan-sitafloxacin-amoxicillin was 80.6% (95% CI, 75.2-85.0). The vonoprazan-sitafloxacin-amoxicillin regimen was significantly superior to the PPI-sitafloxacin-amoxicillin regimen (pooled OR of successful eradication: 6.00; 95% CI: 2.25-15.98, p < 0.001). The PPI-sitafloxacin-amoxicillin regimen was comparable with PPI-sitafloxacin-metronidazole regimens (pooled OR: 1.06; 95% CI: 0.55-2.07, p = 0.86).

CONCLUSIONS

Although the 7-day regimen composed of vonoprazan, sitafloxacin, and amoxicillin is a good option as the third-line Helicobacter pylori eradication treatment in Japan, the extension of treatment duration should be considered to further improve the eradication rate. Considering the safety concern of fluoroquinolones, sitafloxcin should be used after confirming drug susceptibility.

Evidence-Based Guidelines for the Treatment of Helicobacter pylori Infection in Korea 2020

Helicobacter pylori infection is one of the most common infectious diseases worldwide. Although the prevalence of H. pylori is gradually decreasing, approximately half of the world&#039;s population still becomes infected with this disease. H. pylori is responsible for substantial gastrointestinal morbidity worldwide, with a high disease burden. It is the most common cause of gastric and duodenal ulcers and gastric cancer. Since the revision of the H. pylori clinical practice guidelines in 2013 in Korea, the eradication rate of H. pylori has gradually decreased with the use of a clarithromycin-based triple therapy for 7 days. According to a nationwide randomized controlled study conducted by the Korean College of Helicobacter and Upper Gastrointestinal Research released in 2018, the intention-to-treat eradication rate was only 63.9%, which was mostly due to increased antimicrobial resistance, especially from clarithromycin. The clinical practice guidelines for the treatment of H. pylori were updated according to evidence-based medicine from a meta-analysis conducted on a target group receiving the latest level of eradication therapy. The draft recommendations developed based on the meta-analysis were finalized after an expert consensus on three recommendations regarding the indication for treatment and eight recommendations for the treatment itself. These guidelines were designed to provide clinical evidence for the treatment (including primary care treatment) of H. pylori infection to patients, nurses, medical school students, policymakers, and clinicians. These may differ from current medical insurance standards and will be revised if more evidence emerges in the future.

Salvage Regimens after Failure of Previous Helicobacter pylori Eradication Therapy: A Systematic Review and Meta-analysis

Background/Aims: As antibiotic resistance increases and new first-line therapies emerge, salvage therapies for <i>Helicobacter pylori</i> (<i>H. pylori</i>) eradication failures are becoming more common and complicated. This study aimed to systematically review overall salvage regimens after previous failure of <i>H. pylori</i> eradication.Materials and Methods: A systematic review of randomized clinical trials evaluating salvage therapies after previous <i>H. pylori</i> eradication failure was performed. A meta-analysis was conducted when an adequate number of studies suitable for grouping was found.Results: Overall, 36 studies with 77 treatment arms were identified, and they were highly heterogeneous regarding previously failed regimens and salvage regimens under comparison. Bismuth quadruple therapy after failure of standard triple therapy showed a pooled intention-to-treat (ITT) eradication rate of 75.5% (95% CI, 71.6~79.1%), and the rates were significantly higher with 14-day therapy than 7-day therapy by 9% (95% CI, 2~15%). Levofloxacin triple therapy after failure of standard triple therapy demonstrated a pooled ITT eradication rate of 73.3% (95% CI, 68.4~77.3%). In direct comparison, the two regimens were not significantly different in eradication rates. No study evaluated salvage regimens after the failure of bismuth or non-bismuth quadruple therapy.Conclusions: The current studies regarding salvage regimens are highly heterogeneous. Bismuth quadruple therapy and levofloxacin triple therapy may be a reliable option after failure of standard triple therapy, but the regional profile of antibiotic resistance should be considered. Further studies are needed for salvage regimens after failure of non-bismuth or bismuth quadruple therapy.

Evidence-based Guidelines for the Treatment of Helicobacter pylori Infection in Korea: 2020 Revised Edition

Helicobacter pylori (H. pylori) infection is one of the most common infectious diseases worldwide. Although its incidence is gradually decreasing, about half of the world's population still get infected. H. pylori infection is responsible for substantial gastrointestinal morbidity worldwide. It is the most common cause of gastric and duodenal ulcers as well as gastric cancer. Since the revision of the H. pylori Clinical Practice Guidelines in 2013, the eradication rate of H. pylori has gradually decreased with the use of classical triple therapy, wherein amoxicillin, clarithromycin, and proton pump inhibitors are administered, for 7 days. According to a nationwide randomized controlled study conducted by the Korean College of Helicobacter and Upper Gastrointestinal Research released in 2018, the intention-to-treat eradication rate was only 63.9%, which was due to increased antimicrobial resistance induced by the use of antibiotics, especially clarithromycin. The update of clinical practice guideline for treatment of H. pylori was developed based on evidence-based medicine by conducting a meta-analysis. The draft recommendations were finalized after expert consensus on three recommendations regarding the indication for treatment and eight recommendations on the treatment itself. These guidelines are designed to provide patients, nurses, medical school students, policymakers, and clinicians with clinical evidence to guide primary care and treatment of H. pylori infection. These may differ from current medical insurance standards and will be revised further, if necessary, based on research-based evidence.

A combination of serum anti-Helicobacter pylori antibody titer and Kyoto classification score could provide a more accurate diagnosis of H pylori

Background

We previously showed that the endoscopic Kyoto classification for gastritis could predict Helicobacter pylori infection in individuals with a high negative titer of serum anti-H pylori antibodies. This study evaluated H pylori infection and the Kyoto classification score in patients with a low negative titer (<3 U/ml), high negative titer (3–9.9 U/ml), low positive titer (10–49.9 U/ml), and high positive titer (≥50 U/ml).

Methods

Serum antibody levels, Kyoto classification score and histology were investigated in 870 individuals with no history of H pylori-eradication therapy. Urea breath tests (UBTs) were additionally conducted for patients with a low negative titer and a Kyoto score ≥1 or an antibody titer ≥10 U/ml and a Kyoto score of 0 or 1. UBTs and/or histological studies were conducted for participants with a high negative titer.

Results

False diagnoses based on anti-H pylori antibody titers were observed in 0.3% of the low-negative-titer group, 11.7% of the high-negative-titer group, 18.9% of the low-positive-titer group and 2.2% of the high-positive-titer group. Surprisingly, false diagnoses based on antibody titers were noted in 63.2% of patients with a low positive titer and a Kyoto score of 0 and in 62.5% of patients with a high negative titer and a Kyoto score ≥2, respectively.

Conclusions

Endoscopic findings could predict false diagnoses determined using serum antibody titers.

ACG Clinical Guideline: Treatment of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) infection is a common worldwide infection that is an important cause of peptic ulcer disease and gastric cancer. H. pylori may also have a role in uninvestigated and functional dyspepsia, ulcer risk in patients taking low-dose aspirin or starting therapy with a non-steroidal anti-inflammatory medication, unexplained iron deficiency anemia, and idiopathic thrombocytopenic purpura. While choosing a treatment regimen for H. pylori, patients should be asked about previous antibiotic exposure and this information should be incorporated into the decision-making process. For first-line treatment, clarithromycin triple therapy should be confined to patients with no previous history of macrolide exposure who reside in areas where clarithromycin resistance amongst H. pylori isolates is known to be low. Most patients will be better served by first-line treatment with bismuth quadruple therapy or concomitant therapy consisting of a PPI, clarithromycin, amoxicillin, and metronidazole. When first-line therapy fails, a salvage regimen should avoid antibiotics that were previously used. If a patient received a first-line treatment containing clarithromycin, bismuth quadruple therapy or levofloxacin salvage regimens are the preferred treatment options. If a patient received first-line bismuth quadruple therapy, clarithromycin or levofloxacin-containing salvage regimens are the preferred treatment options. Details regarding the drugs, doses and durations of the recommended and suggested first-line and salvage regimens can be found in the guideline.

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

Helicobacter pylori (H. pylori) is a very common bacterium that infects about 50% of the world population in urban areas and over 90% of people living in rural and developing countries. Fluoroquinolones, a class of antimicrobials, have been extensively used in eradication regimens for H. pylori. Levofloxacin is the most commonly used, and in second-line regimens, is one of the most effective options. However, an increasing resistance rate of H. pylori to fluoroquinolones is being observed, that will likely affect their effectiveness in the near future. Other novel fluoroquinolone molecules, such as moxifloxacin, sitafloxacin, gatifloxacin and gemifloxacin, have been proposed and showed encouraging results in vitro, although data on their clinical use are still limited. Further studies in large sample trials are needed to confirm their safety and efficacy profile in clinical practice.

Systematic review and meta-analysis: susceptibility-guided versus empirical antibiotic treatment for Helicobacter pylori infection

BACKGROUND

The cure rate of standard triple therapy for Helicobacter pylori infection is unacceptably low. Susceptibility-guided therapies (SGTs) have been proposed as an alternative to standard empirical treatments. The aim of this study was to perform a systematic review and meta-analysis evaluating the efficacy of SGTs.

METHODS

A systematic search was performed in multiple databases. Randomized controlled trials comparing cure rates of SGTs versus those of empirical therapy were selected and analysed separately for first- and second-line treatments. A meta-analysis was performed using risk ratio (RR) and number needed to treat (NNT) to measure the effect.

RESULTS

Twelve studies were included in the meta-analysis. In first-line treatment, SGT was more efficacious than empirical 7-10 day triple therapy (RR 1.16, 95% CI 1.10-1.23, I (2) = 33%; NNT = 8). Most studies used a 7-10 day triple therapy and randomized the patients after endoscopy and/or culture, thus precluding the comparison of SGT versus non-invasive testing and empirical treatment in clinical practice. For second-line therapy, only four studies were found. Results were highly heterogeneous and no significant differences were found (RR 1.11, 95% CI 0.82-1.51, I (2) = 87%).

CONCLUSIONS

Once endoscopy and culture have been performed, SGT is superior to empirical 7 or 10 day triple therapy for first-line treatment. Further studies are needed to evaluate the effectiveness of SGT in clinical practice, especially when compared with currently recommended first-line quadruple therapies.

Effect of supplementation with rebamipide for Helicobacter pylori eradication therapy: a systematic review and meta-analysis

BACKGROUND AND AIM

Several studies have reported that the application of rebamipide during the eradication of Helicobacter pylori can improve the eradication rate. However, the efficacy and safety are controversial. The present study systematically evaluated whether rebamipide improves the eradication rate of H. pylori by conducting a meta-analysis based on randomized controlled trials (RCTs).

METHODS

Literature searches were conducted in the following database: PubMed, the Cochrane Library, and the Igaku-chuo-zasshi database in Japan. A meta-analysis of all RCTs comparing rebamipide supplementation with non-rebamipide-containing therapy was performed.

RESULTS

We identified six randomized trials (611 patients). Pooled H. pylori eradication rates by per-protocol analysis were 73.3% and 61.4% for patients with or without rebamipide, respectively. The odds ratio was 1.74 (95% confidence interval. 1.19-2.53).

CONCLUSIONS

Supplementation with rebamipide might be effective in increasing the H. pylori eradication rates of proton-pump inhibitor-amoxicillin dual therapy.

Mechanisms of Helicobacter pylori antibiotic resistance and molecular testing

Antibiotic resistance in Helicobacter pylori (H.pylori) is the main factor affecting the efficacy of current treatment methods against infection caused by this organism. The traditional culture methods for testing bacterial susceptibility to antibiotics are expensive and require 10–14 days. Since resistance to clarithromycin, fluoroquinolone, and tetracycline seems to be exclusively caused by specific mutations in a small region of the responsible gene, molecular methods offer an attractive alternative to the above-mentioned techniques. The technique of polymerase chain reaction (PCR) is an accurate and rapid method for the detection of mutations that confer antibiotic resistance. This review highlights the mechanisms of antibiotic resistance in H. pylori and the molecular methods for antibiotic susceptibility testing.

Molecular approaches and modern clinical strategies for the management of Helicobacter pylori infection in Japan

Thirty years have passed since Warren and Marshall's discovery of Helicobacter pylori (H. pylori). Since then, not only peptic ulcer diseases and chronic gastritis but also non-cardia gastric cancers have been recognized as diseases originating from H. pylori infection. Several combination therapies consisting of multiple antibiotics have been developed as first- or second-line regimens to eradicate H. pylori infection. Our extensive experience in the field of anti-H. pylori medicine suggests that clinicians should consider a possible role for unidentified, invisible pathogens to elucidate the pathogenesis and improve the treatment of refractory diseases of unknown etiology.

Delay of second-line eradication therapy for Helicobacter pylori can increase eradication failure

BACKGROUND AND AIM

The interval between first-line Helicobacter pylori eradication treatment and second-line treatment may be critical to the second-line therapeutic effect. We attempted to assess the association between the second-line eradication rates and the treatment interval.

METHODS

Data of patients, who were administered the second-line H. pylori eradication regimen at Tokyo Medical Center between 2008 and 2012, were reviewed.

RESULTS

Of the 148 patients enrolled, one patient dropped out. The eradication rates were 88.6% (intention-to-treat [ITT]) and 89.3% (per-protocol [PP]) for early eradication group (eradication interval < 180 days, patients number 132) and 68.8% (ITT and PP) for delayed eradication group (eradication interval ≥ 180 days, patients number 16). The eradication rate in the delayed eradication group was significantly lower than in the early eradication group (P = 0.027 [ITT] and 0.021 [PP]). The eradication interval in the subjects showing eradication failure (124.0 ± 96.8 days, patients number 19) was significantly longer than those showing successful eradication (85.8 ± 56.9 days, patients number 128, P = 0.008).

CONCLUSION

Our results suggest that the delay of second-line treatment should be avoided.

Dual therapy for third-line Helicobacter pylori eradication and urea breath test prediction

We evaluated the efficacy and tolerability of a dual therapy with rabeprazole and amoxicillin (AMX) as an empiric third-line rescue therapy. In patients with failure of first-line treatment with a proton pump inhibitor (PPI)-AMX-clarithromycin regimen and second-line treatment with the PPI-AMX-metronidazole regimen, a third-line eradication regimen with rabeprazole (10 mg q.i.d.) and AMX (500 mg q.i.d.) was prescribed for 2 wk. Eradication was confirmed by the results of the ¹³C-urea breath test (UBT) at 12 wk after the therapy. A total of 46 patients were included; however, two were lost to follow-up. The eradication rates as determined by per-protocol and intention-to-treat analyses were 65.9% and 63.0%, respectively. The pretreatment UBT results in the subjects showing eradication failure; those patients showing successful eradication comprised 32.9 ± 28.8 permil and 14.8 ± 12.8 permil, respectively. The pretreatment UBT results in the subjects with eradication failure were significantly higher than those in the patients with successful eradication (P = 0.019). A low pretreatment UBT result (≤ 28.5 permil) predicted the success of the eradication therapy with a positive predictive value of 81.3% and a sensitivity of 89.7%. Adverse effects were reported in 18.2% of the patients, mainly diarrhea and stomatitis. Dual therapy with rabeprazole and AMX appears to serve as a potential empirical third-line strategy for patients with low values on pretreatment UBT.

Resistance of Helicobacter pylori strains to antibiotics in Korea with a focus on fluoroquinolone resistance

BACKGROUND AND AIM

New regimens, including those with new fluoroquinolones, have been developed to overcome the antibiotic resistance of Helicobacter pylori. We aimed to assess the antibiotic resistance rates, as well as the molecular mechanisms of fluoroquinolone resistance, of the clinical isolates obtained in Korea.

METHODS

The minimal inhibitory concentration (MIC) values of ciprofloxacin, amoxicillin, clarithromycin, metronidazole and tetracycline were determined by the agar dilution method for 185 treatment-naïve Helicobacter pylori isolates. The resistant strains were evaluated for the presence of point mutations in the quinolone resistance-determining region (QRDR) of the gyrA and gyrB genes by direct nucleotide sequencing.

RESULTS

Twenty-nine (29/185, 15.7%) of the strains were found to be resistant to ciprofloxacin. The resistance rates to amoxicillin, clarithromycin, metronidazole and tetracycline were 2.2% (four of 185), 10.8% (20 of 185), 30.3% (56 of 185) and 0.5% (one of 185), respectively. The most common mutations in the H. pylori gyrA gene were found at codons corresponding to Asp87 (16/29, 55.2%) and Asn91 (10/29, 34.5%).

CONCLUSIONS

Primary H. pylori resistance to ciprofloxacin occurred at a high frequency. The fluoroquinolone resistance is most likely mediated through amino acid point mutation in the gyrA gene at Asn87 and Asp91.

Efficacy of sitafloxacin-based rescue therapy for Helicobacter pylori after failures of first- and second-line therapies

Sitafloxacin-based triple therapy achieved 83.6% (per-protocol) and 78.2% (intention-to-treat) success in eradicating Helicobacter pylori among 78 Japanese patients after clarithromycin-based first-line and metronidazole-based second-line triple therapies failed. Eradication succeeded in 32 out of 43 patients, even with gyrA mutation-positive Helicobacter pylori (per protocol). The position of the gyrA mutation (N87 or D91) was determined to be a better marker than MIC levels for predicting outcomes of sitafloxacin-based treatment.

Helicobacter pylori resistance to rifabutin in the last 7 years

A low rate of resistance (0.24%) to rifabutin was noted in Helicobacter pylori strains isolated from 414 Japanese patients. The only rifabutin-resistant strain detected showed a point mutation in the rpoB gene and was isolated from a patient with a history of rifampin treatment for pulmonary tuberculosis.

Mutations of Helicobacter pylori associated with fluoroquinolone resistance in Korea

BACKGROUND AND AIM

Fluoroquinolone resistance of Helicobacter pylori is known to be dependent on mutations in the QRDR of gyrA. This study was performed to investigate the distribution of gyrA point mutations and to evaluate the impact of the mutations on second-line H. pylori eradication therapy.

METHODS

After H. pylori isolation from gastric mucosal specimens, fluoroquinolone resistance was examined using the agar dilution method. DNA sequencing of the QRDR of gyrA was performed in 89 fluoroquinolone-resistant and 27 fluoroquinolone-susceptible isolates. Transformation experiments were performed to confirm mutations in the resistant strains. The eradication rates of moxifloxacin-containing triple therapy were evaluated depending on the resistance of fluoroquinolone.

RESULTS

The gyrA mutations were detected in 75.3% (55 of 73 strains) of the primary resistant strains and 100% (16 strains) of the secondary resistant strains. The most common mutations were Asp-91 (36.0%) and Asn-87 (33.7%). The MIC values in the transformed strains differed depending on the gyrA mutations, N87, and D91. Six patients with fluoroquinolone-resistant strains received moxifloxacin-containing triple therapy as the second-line therapy, and two of three patients with Asn-87 mutations (66.7%) failed in the eradication. By contrast, three patients with Asp-91 mutations had successful eradication treatment.

CONCLUSIONS

Fluoroquinolone resistance of H. pylori was caused by gyrA Asn-87 and Asp-91 point mutations. The Asn-87 mutation seems to be an important determinant of failure of fluoroquinolone-containing triple eradication therapy based on eradication results.

Enhancement of amoxicillin resistance after unsuccessful Helicobacter pylori eradication

A high rate of resistance (49.5 to 72.7%) to amoxicillin (AMX) was observed in Helicobacter pylori after two or three unsuccessful eradication attempts. Unsuccessful eradication regimens significantly increase resistance to not only clarithromycin (CLR) and metronidazole (MNZ) but also AMX.

Helicobacter pylori eradication therapy

Helicobacter pylori infection is the main cause of gastritis, gastroduodenal ulcers and gastric cancer. H. pylori eradication has been shown to have a prophylactic effect against gastric cancer. According to several international guidelines, the first-line therapy for treating H. pylori infection consists of a proton pump inhibitor (PPI) or ranitidine bismuth citrate, with any two antibiotics among amoxicillin, clarithromycin and metronidazole, given for 7-14 days. However, even with these recommended regimens, H. pylori eradication failure is still seen in more than 20% of patients. The failure rate for first-line therapy may be higher in actual clinical practice, owing to the indiscriminate use of antibiotics. The recommended second-line therapy is a quadruple regimen composed of tetracycline, metronidazole, a bismuth salt and a PPI. The combination of PPI-amoxicillin-levofloxacin is a good option as second-line therapy. In the case of failure of second-line therapy, the patients should be evaluated using a case-by-case approach. European guidelines recommend culture before the selection of a third-line treatment based on the microbial antibiotic sensitivity. H. pylori isolates after two eradication failures are often resistant to both metronidazole and clarithromycin. The alternative candidates for third-line therapy are quinolones, tetracycline, rifabutin and furazolidone; high-dose PPI/amoxicillin therapy might also be promising.

Homology model of the DNA gyrase enzyme of Helicobacter pylori, a target of quinolone-based eradication therapy

BACKGROUND AND AIMS

Resistance of Helicobacter pylori to the standard therapeutic antimicrobial agents has been demonstrated. Although quinolones are an alternative candidate for third-line eradication therapy, quinolone resistance of H. pylori is also increasing. Quinolone resistance of H. pylori is caused by a point mutation of the DNA gyrase subunit A (GyrA) protein, especially on amino acids 87 and 91. The aim of this study is to surmise the structure of H. pylori GryA.

METHODS

The modeling of the 3-D structure of H. pylori GyrA was performed by an automated homology modeling program: SWISS-MODEL. The position of amino acids 87 and 91 in H. pylori GyrA was plotted on the homology model. To estimate the function of quinolone resistance-determining region (QRDR), the structure of H. pylori GyrA was compared with Escherichia coli GyrA.

RESULTS

A molecular model of H. pylori GyrA could be predicted using SWISS-MODEL. The GyrA N- and C-terminal domains closely resembled those of E. coli. The position of amino acids 87 and 91 in H. pylori GyrA was part of the DNA binding region (head dimer interface) on the GyrA N-terminal domain.

CONCLUSION

Our homology model of H. pylori GryA suggests that the quinolone resistance-determining region is on the head dimer interface of the GyrA N-terminal domain.

Quinolone-Based Third-Line Therapy for Helicobacter pylori Eradication

Currently, a standard third-line therapy for Helicobacter pylori (H. pylori) eradication remains to be established. Quinolones show good oral absorption, no major side effects, and marked activity against H. pylori. Several authors have studied quinolone-based third-line therapy and reported encouraging results, with the reported H. pylori cure rates ranging from 60% to 84%. Resistance to quinolones is easily acquired, and the resistance rate is relatively high in countries with a high consumption rate of these drugs. We recently reported a significant difference in the eradication rate obtained between patients infected with gatifloxacin-susceptible and gatifloxacin-resistant H. pylori, suggesting that the selection of quinolones for third-line therapy should be based on the results of drug susceptibility testing. As other alternatives of third-line rescue therapies, rifabutin-based triple therapy, high-dose proton pump inhibitor/amoxicillin therapy and furazolidone-based therapy have been suggested.