Prospective multicentre study on antibiotic resistance of Helicobacter pylori strains obtained from children living in Europe

Detection of Helicobacter pylori and clarithromycin resistance in gastric biopsies of pediatric patients by using a commercially available real-time polymerase chain reaction after NucliSens semiautomated DNA extraction

The aim of this study was to evaluate a commercially available kit, MutaREAL Helicobacter pylori (Inmundiagnostik, Bensheim, Germany) real-time polymerase chain reaction (PCR), for detection of H. pylori infection and point mutations in the 23S rRNA genes responsible for clarithromycin resistance in gastric biopsies.

METHODS

Gastric biopsies were obtained by endoscopy from pediatric patients with gastric symptoms, cultured according to standard microbiologic procedures, and clarithromycin resistance was determined by E-test. DNA extraction was performed by NucliSens platform with the NucliSens magnetic extraction reagents (bioMérieux, Marcy-l'Etoile, France) according to the manufacturer's instructions. MutaREAL kit was used according to manufacturer recommendations in a LightCycler (Roche Diagnostics Gmbh, Mannheim, Germany) for the detection of H. pylori infection and clarithromycin susceptibility.

RESULTS

Amplification was positive for H. pylori in 62 and negative in 44 biopsies out of 106 biopsies. All negative biopsies were positive for human beta-globin gene. This real-time PCR assay showed sensitivity of 93.33% (negative predictive value, 90.90%) and specificity of 86.95% (positive predictive value, 90.32%) for H. pylori detection. Clarithromycin resistance was detected in 26 cases by PCR with a sensitivity and specificity of 90.62 and 95.83, respectively.

CONCLUSIONS

MutaREAL kit was able to detect H. pylori and its clarithromycin susceptibility with high efficacy. This method is quicker than culture and is suitable to be done in 1 h after DNA extraction. The new system of automatic extraction will lead to reduction in the total time.

Treatment of Helicobacter pylori infection 2010

It is accepted that the success of Helicobacter pylori eradication treatment using standard triple therapy is declining. Resistance, particularly to clarithromycin, has been shown in numerous countries to be rising to a level where the use of standard triple therapy in its current form may no longer be justified. The two major factors influencing resistance are prior exposure to the antibiotic and compliance with therapy. Regimes based on bismuth and levofloxacin, which had previously been mainly second-line options, are now emerging as superior first-line options. Trials of sequential and concomitant therapies are also showing the usefulness of these treatments in different populations. Options for third and subsequent line therapies include furazolidone and rifabutin-based regimes. Susceptibility testing should be performed to maintain accurate data on resistance levels, and has also clinical utility in difficult to eradicate cases. None of these, however, will be successful unless compliance is improved upon. If compliance is assured and eradication confirmation pursued, it has been repeatedly illustrated that near full eradication is achievable.

Helicobacter pylori therapy in children: overview and challenges

Helicobacter pylori is one of the most common infections found in humans. It was first identified in 1982 and by 1989 had been associated with gastric inflammation and ulcers in adults and children. During the 1990's evidence emerged of its etiologic role in stomach cancers in adults. That the infection is common and may have serious consequences, has led to an avalanche of research during the last twenty years. During this time, there have been many studies on children which have sought an effective and safe treatment to eradicate the infection, but as yet, no therapy regimen has been found which is always effective and safe. This article provides information, from a pediatric point of view, on the major developments in the therapeutics and therapy of H. pylori infection. It examines first-line treatment regimens, evaluates the efficacy of the main drugs used in the management of (primary) H. pylori infection in children, assesses the potential for the use of probiotics and sequential therapy, examines therapeutic options after failure of initial treatment, and discusses factors affecting eradication rate, including antibiotic resistance, adherence to therapy, and bacterial factors.

Primary resistance to clarithromycin, metronidazole and amoxicillin of Helicobacter pylori isolated from Tunisian patients with peptic ulcers and gastritis: a prospective multicentre study

BACKGROUND

The frequency of primary resistance to antibiotics in H. pylori isolates is increasing worldwide. In Tunisia, there are limited data regarding the pattern of H. pylori antibiotic primary resistance.

AIM

To evaluate the primary resistance of H. pylori to clarithromycin, metronidazole and amoxicillin and to detect the mutations involved in clarithromycin resistance.

MATERIALS AND METHODS

273 strains isolated from adults and children were enrolled. The primary resistance to clarithromycin, metronidazole and amoxicillin was evaluated by means of E-test minimal inhibitory concentration (MIC). The real-time PCR using Scorpion primers was performed in all cases to assess clarithromycin primary resistance and point mutations involved.

RESULTS

No resistance to amoxicillin was detected. For adults, resistance to clarithromycin and metronidazole was found respectively in 14.6% and 56.8%, and respectively in 18.8% and 25% in children. Overall, the rates of global primary resistance to clarithromycin and metronidazole in Tunisia were respectively determined in 15.4% and 51.3%.By the use of Scorpion PCR, the A2143G was the most frequent point mutation observed (88.1%), followed by the A2142G (11.9%); the A2142C was not found and 18 of 42 patients (42.8%) were infected by both the resistant and the susceptible genotype.The association of clarithromycin resistance with gender was not statistically significant, but metronidazole resistant strains were isolated more frequently in females (67.8%) than in males (32.2%) and the difference was significant. As for gastroduodenal diseases, the difference between strains isolated from patients with peptic ulceration and those with non peptic ulceration was not statistically significant. When about the distribution of resistant strains to clarithromycin and metronidazole between the three Tunisian cities (Tunis, Menzel Bourguiba and Mahdia), the difference was not statistically significant.

CONCLUSION

Local data regarding the primary resistance of H. pylori to clarithromycin, metronidazole and amoxicillin and the main genetic mutation involved in clarithromycin resistance in vivo (A2143G) are necessary to prove a clear need for a periodic evaluation of antibiotic consumption and new therapeutic strategies in Tunisia in order to avoid the emergence of resistant strains.

High prevalence of clarithromycin-resistant Helicobacter pylori strains and risk factors associated with resistance in Madrid, Spain

Clarithromycin is one of the antibiotics used for the treatment of Helicobacter pylori infections, and clarithromycin resistance is the most important factor when it comes to predicting eradication failure. The present study analyzed H. pylori isolates for the presence of 23S rRNA gene mutations and determined the risk factors associated with resistance among H. pylori isolates collected in Madrid, Spain, in 2008. We studied 118 H. pylori strains isolated from the same number of patients. A total of 76.3% of the patients were born in Spain, 52.7% were children, 20.3% had previously been treated, and 66.1% were female. Clarithromycin resistance was determined by Etest. H. pylori strains were considered resistant if the MIC was ≥1 mg/liter. DNA extraction was carried out by use of the NucliSens easyMAG platform with NucliSens magnetic extraction reagents (bioMérieux). The DNA sequences of the 23S rRNA genes of clarithromycin-resistant and -sensitive strains were determined to identify specific point mutations. The vacA genotype and cagA status were determined by PCR. We found that 42 (35.6%) strains were resistant to clarithromycin by Etest. Etest results were confirmed by detection of the presence of point mutations in 34 (88.1%) of these strains. Eight H. pylori strains were resistant to clarithromycin by Etest but did not have a point mutation in the 23S rRNA gene. Mutation at A2143G was found in 85.3% of the strains, mutation at A2142G in 8.8%, and mutation at T2182C in 5.9%. Dual mutations were found in 8.8% of the strains. H. pylori clarithromycin-resistant strains were strongly associated with pediatric patients, with patients born in Spain, and with patients who had previously been treated (P ≤ 0.02). In addition, H. pylori strains resistant to clarithromycin more frequently presented the vacA s2/m2 genotype and were more likely to be cagA negative than susceptible strains (39.1% and 11.2%, respectively; P value < 0.001). We concluded that, in the present study, H. pylori clarithromycin-resistant strains are more frequently found in children, in patients mostly born in Spain, and in individuals who were previously treated for H. pylori infection and that these individuals are more likely colonized with a less virulent H. pylori strain.

Geographic map and evolution of primary Helicobacter pylori resistance to antibacterial agents

Antibiotic resistance in Helicobacter pylori is the major cause of eradication failure. Primary H. pylori susceptibility patterns, however, are becoming less predictable. Currently, high (> or =20%) clarithromycin resistance rates have been observed in the USA and in developed countries in Europe and Asia, while the highest (> or =80%) metronidazole-resistance rates have been reported in Africa, Asia and South America. Primary quinolone-resistance rates of 10% or more have already been reported in developed countries in Europe and Asia. Primary amoxicillin resistance has been low (0 to <2%) in Europe but higher (6-59%) in Africa, Asia and South America. Similarly, tetracycline resistance has been absent or low (<5%) in most countries and higher (9-27%) in Asia and South America. The increasing clarithromycin and quinolone resistance, and multidrug resistance detected in 0 to less than 5% in Europe and more often (14.2%) in Brazil are worrying. Growing resistance often parallels national antibiotic consumption and may vary within patient groups according to the geographic region, patient's age and sex, type of disease, birthplace, other infections and other factors. The geographic map and evolution of primary H. pylori resistance are clinically important, should be considered when choosing eradication regimens, and should be monitored constantly at national and global levels in an attempt to reach the recently recommended goal of eradication of more than 95%.

Time trends of Helicobacter pylori resistance to antibiotics in children living in Vienna, Austria

BACKGROUND

Increase of antibiotic resistance is a worldwide problem. Within the 4 years before the turn of the millennium Helicobacter pylori strains isolated in children living in Vienna, Austria, showed a primary clarithromycin and metronidazole resistance of 20% and 16%, respectively. The aim of this retrospective follow-up survey was to assess the further development and current antimicrobial resistance status.

METHODS

Children having undergone upper endoscopy between March 2002 and March 2008 at the same two co-operating pediatric gastroenterology units which had also been collaborating on the prior assessment were included. H. pylori infection was diagnosed by rapid urease test, histology, and culture. If the latter was positive, susceptibility testing to amoxicillin, clarithromycin and metronidazole by E-test followed. From March 2004 onwards, susceptibility to levofloxacin, tetracycline and rifampin was additionally assessed.

RESULTS

Out of 897 children, 153 had a proven infection with H. pylori and no history of prior eradication treatment. Their median age was 11.5 years (range 0.5-20.9 years). Primary resistance to clarithromycin and metronidazole were 34% and 22.9%, respectively; dual resistance was found in 9.8% of the strains; 0.9% was resistant to tetracycline and rifampin, respectively. No case of amoxicillin resistance was detected. The only independent risk factor for clarithromycin resistance turned out to be the origin of a child from Austrian parents.

CONCLUSIONS

In the last decade, the rate of primary resistance of H. pylori to clarithromycin continued to rise. No significant change was found regarding primary resistance to metronidazole or dual resistance to metronidazole and clarithromycin, respectively.

Ten and eight-day sequential therapy in comparison to standard triple therapy for eradicating Helicobacter pylori infection: a randomized controlled study on efficacy and tolerability

BACKGROUND

Sequential therapy (SQT) is effective in the eradication of Helicobacter pylori and could become an alternative to standard triple therapy (STT).

AIM

To compare the efficacy and tolerability of SQT, for either 8 or 10 days, with a 7-day STT.

METHODS

A total of 270 naive H. pylori-positive patients were randomized to receive: SQT for 8 days (SQT-8, n=90) or 10 days (SQT-10, n=90) including esomeprazole 20 mg twice daily (bid) associated with amoxicillin 1000 mg bid (early 4 and 5 d, respectively), followed by esomeprazole 20 mg bid associated with clarithromycin 500 mg bid plus tinidazole 500 mg bid (last 4 and 5 d, respectively); STT (n=90) including esomeprazole 20 mg bid plus amoxicillin 1000 mg bid and clarithromycin 500 mg bid for 7 days. Tolerability was assessed by scoring the severity of symptoms.

RESULTS

Eradication rates after SQT-8 and SQT-10 were higher than that of after STT at both intention-to-treat (83% and 86% vs. 66%, P<0.02) and per-protocol analysis (90% and 88% vs. 75%, P<0.05), whereas no difference was found between the 2 SQTs.

CONCLUSIONS

This study shows that SQT, for 8 or 10 days, is well tolerated and highly effective in H. pylori eradication and could represent a valid alternative to STT. Further studies, with more power, on larger populations and from other countries are necessary to validate the present findings.

Primary antimicrobial resistance of Helicobacter pylori in children during the past 9 years

BACKGROUND

Antimicrobial resistance of Helicobacter pylori is a growing problem in clinical practice, particularly clarithromycin resistance. The aim of the present study was therefore to investigate the prevalence of H. pylori resistance to antimicrobial agents in Japanese children.

METHODS

A total of 61 H. pylori strains isolated from children (mean age, 12.6 years; range, 4-18 years) between 1999 and 2007 were studied for primary antimicrobial resistance, using a microdilution method. In addition, the eradication rate with lansoprazole-based triple regimens was determined.

RESULTS

The overall resistance rate of clarithromycin, amoxicillin and metronidazole was 36.1%, 0% and 14.8%, respectively. Resistance to both clarithromycin and metronidazole was detected in 6.6% of the strains. The rate of clarithromycin-resistant strains was 32.4% from 1999 to 2002 and 40.7% from 2003 to 2007, and clarithromycin minimum inhibitory concentration at which 90% of the isolates were inhibited (MIC(90)) increased fourfold from 1999-2002 to 2003-2007, with all clarithromycin-resistant strains showing low-level resistance. Metronidazole resistance rates were not different between these two study periods. Regimens involving amoxicillin and clarithromycin (n= 49) had a higher eradication rate in clarithromycin-susceptible strains (97.1%) than in the resistant strains (57.1%; P < 0.001). There was no difference in the eradication rate between 7 day and 10 or 14 day courses of the regimens (P= 0.53). The regimen with amoxicillin and metronidazole produced successful eradication in all nine patients with clarithromycin-resistant strains.

CONCLUSIONS

Clarithromycin resistance of H. pylori is high, and triple regimen treatment containing clarithromycin should be decided based on susceptibility to the agent.

High level of antimicrobial resistance in French Helicobacter pylori isolates

BACKGROUND

Helicobacter pylori is a human pathogen responsible for serious diseases including peptic ulcer disease and gastric cancer. The recommended triple therapy included clarithromycin but increasing resistance has undermined its effectiveness. It is therefore important to be aware of the local prevalence of antimicrobial resistance to adjust treatment strategy.

MATERIALS AND METHODS

Overall, 530 biopsies were collected between 2004 and 2007. The antimicrobial susceptibility of H. pylori was determined by E-test and molecular methods.

RESULTS

Among these, 138/530 (26%) strains were resistant to clarithromycin, 324/530 (61%) to metronidazole and 70/530 (13.2%) to ciprofloxacin. Whereas no resistance against amoxicillin and tetracycline was observed, only one strain was resistant to rifampicin. Compared to the patients never treated for H. pylori infection, the prevalence of resistance was significantly higher in patients previously treated (19.1% vs 68% for clarithromycin; 13.2% vs 53.3% for both clarithromycin and metronidazole). The trend analysis revealed an increase of primary resistance to ciprofloxacin between 2004 and 2005 (7.3%) vs 2006-2007 (14.1%) (p = .04) and the secondary resistance reached 22.7% in 2007. Interestingly, 27 biopsies (19.6%) contained a double population of clarithromycin-susceptible and -resistant strains.

CONCLUSIONS

The reported high prevalence of clarithromycin and multiple resistances of H. pylori suggest that the empiric therapy with clarithromycin should be abandoned as no longer pretreatment susceptibility testing has assessed the susceptibility of the strain. As culture and antibiogram are not routinely performable in most clinical laboratories, the use of molecular test should be developed to allow a wide availability of pretreatment susceptibility testing.

Helicobacter pylori diagnostic tests in children: review of the literature from 1999 to 2009

The array of tests that can be used for diagnosis of Helicobacter pylori infection is large, and it can be confusing to define which test to use particularly in children where results may not be comparable to those obtained in adult patients. Using PubMed, we reviewed the English literature from January 1999 to May 2009 to identify articles that determined sensitivity and specificity of H. pylori invasive and non-invasive diagnostic tests in children. We excluded articles that presented a review of the literature, abstracts, case reports, or series where children's results could not be separated from adult populations. Of the tissue based methods, rapid urease tests have better sensitivity than histology to detect presence of H. pylori; however, histology can detect the pathology associated with disease including gastritis, intestinal metaplasia, and other conditions that could be the cause of the child's symptoms. Culture of gastric tissues or stool has 100% specificity but sensitivity is low. Of the serologic tests, immunoblot has the best sensitivity. The urea breath tests have >75% sensitivity for detection of H. pylori before and after treatment. Immunoassays in stool using monoclonal antibodies have >95% sensitivity for detection of H. pylori before and after treatment. PCR testing can be performed in tissue and stool samples and can detect genes associated to antibiotic resistance. In summary, the current commercial non-invasive tests have adequate sensitivity and specificity for detecting the presence of H. pylori; however, endoscopy with histopathology is the only method that can detect H. pylori and lesions associated with the infection.

Toward the development of a stable, freeze-dried formulation of Helicobacter pylori killed whole cell vaccine adjuvanted with a novel mutant of Escherichia coli heat-labile toxin

No vaccine exists for the prevention of infection with the ubiquitous gastric pathogen Helicobacter pylori, and drug therapy for the infection is complicated by poor patient compliance, the high cost of treatment, and ineffectiveness against drug-resistant strains. A new medical advancement is required to reduce the incidence of peptic ulcer disease and stomach cancer, two conditions caused by infection with H. pylori. Clinical trials have been performed with a formalin-inactivated H. pylori whole cell (HWC) vaccine, given orally in combination with the mucosal adjuvant mLT(R192G), a mutant of Escherichia coli heat-labile toxin. Following the initial dose of this vaccine, some subjects experienced gastrointestinal side effects. To reduce side effects and potentially further increase the amount of adjuvant that can safely be administered with the HWC vaccine, experiments were performed with a form of LT that carried two mutations in the A subunit, a substitution of G for R at position 192, and A for L at position 211. The double mutant LT (dmLT) adjuvant stimulated immune responses as effectively as the single mutant LT in mice. Additionally, following a challenge infection, the dmLT-adjuvanted vaccine was as effective as single mutant LT in reducing gastric urease levels (diagnostic for H. pylori infection), and H. pylori colonization in the stomach as assessed by quantitative analysis of stomach homogenates. A lyophilized formulation of HWC was developed to improve stability and to potentially reduce reliance on cold chain maintenance. It was observed that a dmLT-adjuvanted lyophilized vaccine was equally as protective in the mouse model as the liquid formulation as assessed by gastric urease analysis and analysis of stomach homogenates for viable H. pylori. No readily detectable effect of tonicity or moisture content was observed for the lyophilized vaccine within the formulation limits evaluated. In an accelerated stability study performed at 37 degrees C the lyophilized vaccine remained equally as protective as vaccine stored at 2-8 degrees C. The formulation selected for clinical development consisted of 2.5 x 10(10) formalin-inactivated cells per ml in 6.5% trehalose, 0.5% mannitol, and 10mM citrate buffer at pH 6.8.

Resistance to metronidazole, clarithromycin and levofloxacin of Helicobacter pylori before and after clarithromycin-based therapy in Taiwan

BACKGROUND AND AIM

Clarithromycin-based triple therapy has been commonly applied as the first-line therapy for Helicobacter pylori eradication. Levofloxacin could serve as an alternative in either first-line or second-line regimens. This study surveyed the prevalence of levofloxacin resistance of H. pylori isolates in naive patients and in patients with a failed clarithromycin-based triple therapy.

METHODS

The study collected the H. pylori isolates from 180 naive patients and 47 patients with a failed clarithromycin-based triple therapy. Their in vitro antimicrobial resistance was determined by E-test.

RESULTS

The naive H. pylori isolates had resistance rates for amoxicillin, levofloxacin, clarithromycin and metronidazole of 0%, 9.4%, 10.6% and 26.7%, respectively. An evolutional increase of the primary levofloxacin resistance was observed in isolates collected after 2004, as compared to isolates collected before 2004 (16.3% vs 3.2%, P = 0.003). There was no evolutional increment of the primary clarithromycin resistance. The clarithromycin resistance elevated significantly after a failed clarithromycin-based triple therapy (78.7% vs 10.6%, P < 0.001). The post-treatment isolates remained to have a levofloxacin resistance rate of near 17%, but the levofloxacin-resistant isolates were correlated with a higher incidence of metronidazole resistance (P = 0.023). No strain was found to be resistant to amoxicillin even after eradication failure.

CONCLUSION

The levofloxacin resistance of naive H. pylori remains less than 10% in Taiwan. With relatively lower resistance to levofloxacin than to metronidazole of the H. pylori isolates collected after a failed clarithromycin-based therapy, proton pump inhibitor-levofloxacin-amoxicillin may be an alternative choice to serve as the second-line therapy.

Prevalence of multidrug-resistant Helicobacter pylori in Bulgaria

The aim of this study was to evaluate the presence and prevalence of multidrug antibacterial resistance in Helicobacter pylori in Bulgaria from 2005 to 2008. The resistance in 828 untreated adults, 124 treated adults and 105 untreated children was, respectively, 26.5, 50.8 and 16.2% for metronidazole; 18.4, 45.2 and 19% for clarithromycin; 1, 2.4 and 0% for amoxicillin; 4.4, 10.6 and 1.9% for tetracycline; and 9, 14.5 and 5.8% for ciprofloxacin. Triple resistance to the evaluated agents was uncommon and was detected in 1% of the untreated children, 3.5% of the untreated adults and 13.6% of the treated adults. Five H. pylori strains were resistant to amoxicillin, metronidazole and clarithromycin, two of them exhibiting quadruple resistance. Resistance to four of the five antibacterials tested was found in 0.7% of the untreated and 1.8% of the treated adults. The overall level of multidrug resistance in the treated adults (15.4%) was higher than that in the untreated adults (4.2%, P=0.0001) and the untreated children (1%, P=0.0001). The presence of multidrug H. pylori resistance in Bulgaria could be associated with many factors, among them the slightly increasing national use of macrolides, lincosamides and streptogramins and of quinolones since 2000, the significant increase in primary H. pylori clarithromycin resistance, the high tetracycline use between 1994 and 1999, and, in individual cases, the use of azithromycin-based regimens or reuse of nitroimidazoles. In conclusion, for the first time in a European country during the last 5 years, H. pylori strains harbouring a worrying quadruple antibacterial resistance were found in treated as well as in untreated patients. H. pylori susceptibility patterns have a tendency to become unpredictable and should be monitored constantly at both national and global levels.

Long-term administration of probiotics to asymptomatic pre-school children for either the eradication or the prevention of Helicobacter pylori infection

BACKGROUND

The role of probiotics in the armamentarium remains to be defined. The aims of this study were to investigate whether the long-time administration of Lactobacillus gasseri OLL2716 (LG21) strain can eradicate H. pylori in asymptomatic pre-school children and/or prevent H. pylori infection.

METHODS

A total of 440 children, from 5-7 years of age, attending a kindergarten in Thailand were screened by the Helicobacter pylori stool antigen (HpSA) test. Thereafter 132 H. pylori positive and 308 H. pylori negative children were recruited to eradication and randomized prevention arms, respectively. Children in the active and placebo treatment groups received Lactobacillus gasseri OLL2716 (LG21) containing cheese and ordinary cheese, respectively, for 12 months. Eradication was defined as reversion by HpSA at 12 months. Prevention was defined as persistently HpSA negative at 12 months.

RESULTS

Eighty-two of 132 H. pylori positive (62%) completed the eradication arm, of which 24 (29.3%) were negative at 12 months according to the HpSA test. In the randomized prevention arm, 123 of 156 (79%) and 99 of 122 (81%) completed active and placebo arms, respectively, of which 4.1% and 8.1%, respectively, were HpSA positive at 12 months based on a per-protocol analysis (p = .21).

CONCLUSION

Further trials are needed.

Pediatric Helicobacter pylori isolates display distinct gene coding capacities and virulence gene marker profiles

Helicobacter pylori strains display remarkable genetic diversity, and the presence of strains bearing the toxigenic vacA s1 allele, a complete cag pathogenicity island (PAI), cagA alleles containing multiple EPIYA phosphorylation sites, and expressing the BabA adhesin correlates with development of gastroduodenal disease in adults. To better understand the genetic variability present among pediatric strains and its relationship to disease, we characterized H. pylori strains infecting 47 pediatric North American patients. Prevalence of mixed infection was assessed by random amplified polymorphic DNA analysis of multiple H. pylori clones from each patient. Microarray-based comparative genomic hybridization was used to examine the genomic content of the pediatric strains. The cagA and vacA alleles were further characterized by allele-specific PCR. A range of EPIYA motif configurations were observed for the cagA gene, which was present in strains from 22 patients (47%), but only 19 (41%) patients contained a complete cag PAI. Thirty patients (64%) were infected with a strain having the vacA s1 allele, and 28 patients (60%) had the babA gene. The presence of a functional cag PAI was correlated with ulcer disease (P = 0.0095). In spite of declining rates of H. pylori infection in North America, at least 11% of patients had mixed infection. Pediatric strains differ in their spectrum of strain-variable genes and percentage of absent genes in comparison to adult strains. Most children were infected with H. pylori strains lacking the cag PAI, but the presence of a complete cag PAI, in contrast to other virulence markers, was associated with more severe gastroduodenal disease.

Randomized, double-blind, placebo-controlled trial: effect of lactobacillus GG supplementation on Helicobacter pylori eradication rates and side effects during treatment in children

OBJECTIVE

To determine the effectiveness of Lactobacillus GG (LGG) in children with Helicobacter pylori infection undergoing eradication therapy.

MATERIALS AND METHODS

We conducted a double-blind, placebo-controlled, randomized trial comparing a 7-day, triple eradication regimen consisting of 2 antibiotics (amoxicillin tablets, 25 mg/kg twice per day, and clarithromycin tablets, 10 mg/kg twice per day) plus a proton pump inhibitor (omeprazole capsules, 0.5 mg/kg twice per day) supplemented with LGG (109 colony-forming units) or placebo in 83 children with H pylori infection confirmed by 2 of 3 tests (13C-urea breath test, histopathology, rapid urease test). The primary outcome measure was the H pylori eradication rate. The secondary outcome measure was the proportion of patients who experienced therapy-related adverse effects during anti-H pylori treatment.

RESULTS

The groups did not differ with respect to H pylori eradication rates. Of the 34 children in the LGG group, 23 (69%) experienced eradication, compared with 22 of 32 children (68%) in the placebo group (RR 0.98, 95% CI 0.7-1.4). The groups did not differ with respect to adverse effects.

CONCLUSIONS

In children with H pylori infection, supplementation of standard triple therapy with LGG did not significantly alter the eradication rate or side effects.

Clarithromycin resistance of Helicobacter pylori strains isolated from children' gastric antrum and fundus as assessed by fluorescent in-situ hybridization and culture on four-sector agar plates

AIM

To assess validity of culture on four-sector agar plates and fluorescent in-situ hybridization (FISH) test, and clarithromycin resistance rate in Helicobacter pylori strains isolated from children in the last 10 years.

METHODS

In the last 5 years, gastric biopsy specimens from antrum and fundus were taken from 89 consecutive children (median age 9 years) with H. pylori gastritis and from 21 controls. Culture was performed on 176 gastric biopsies (89 from antrum, 87 from fundus) on four-sector agar plates, and FISH test with DNA ProbeMix. After its validity was evaluated, FISH test was applied on additional 119 biopsies from 68 children (68 from the antrum, 51 from the fundus) stored in the Pathology archive in the previous 5 years.

RESULTS

Culture was positive in 157 of 176 biopsies (sensitivity: 89.2%, 95% confidence interval (CI) 85-94). In 33 of 89 children (37%) resistant strains were found in one or both gastric sites. FISH test was positive in 148 of 176 biopsies from infected children (sensitivity 84.1%, 95%CI 79-89) and in none of 42 biopsies from controls (specificity 100%). When applied on archive biopsies, FISH test was positive in 96 of 119 (80.7%, 95%CI 74-88). Total children harboring resistant strains in the last 10 years, as assessed by FISH test, were 66 of 157 (42%). Mixed infection with both sensitive and resistant strains were found in 40 children (25%) and in 12 of them resistant strains were in the fundus only.

CONCLUSIONS

Culture on four-sector agar plates and FISH test had a high sensitivity and specificity and showed co-presence of sensitive and resistant strains. In one-third of children with mixed infection, the resistant strains were in the fundus only. Clarithromycin resistance should be assessed in biopsies both from the antrum and the fundus, utilizing antral biopsies only can underestimate its prevalence.

Evaluation of two triple-therapy regimens with metronidazole or clarithromycin for the eradication of H. pylori infection in Vietnamese children: a randomized, double-blind clinical trial

BACKGROUND

Eradication of Helicobacter pylori infection in children in developing countries needs further investigations upon which to base treatment recommendations. The aim of the study was to compare two 2-week triple therapies in a randomized double-blind trial.

MATERIALS AND METHODS

In order not to exceed recommended dosages, the 238 H. pylori-infected children, aged 3 to 15 years (mean 8.6), were divided in two weight categories receiving at weights 13-22 kg: lansoprazole 15 mg once-daily and amoxicillin 500 mg twice-daily with metronidazole 250 mg twice-daily or clarithromycin 250 mg once-daily; at weights 23-45 kg: lansoprazole 15 mg and amoxicillin 750 mg with metronidazole 500 mg or clarithromycin 250 mg, all administered twice daily. H. pylori status was assessed by culture and a monoclonal-based antigen-in-stool test (Premier Platinum HpSA PLUS) and side effects by structured questionnaires.

RESULTS

The overall per-protocol eradication (n = 233) was similar in the two treatment regimens, 62.1% for the metronidazole and 54.7% for the clarithromycin-containing therapy. Eradication rate was higher in children >or= 23 kg (70.9%) than in children < 23 kg (45.7%). In children >or= 23 kg (n = 117) that received twice-daily administration of all drugs, efficacy of the metronidazole and clarithromycin-containing treatments were 69.5% and 72.4%, respectively.

CONCLUSIONS

The two treatments gave similar eradication rates. Significant differences for both treatments were found by weight, which could be the result of the once-daily proton pump inhibitor and clarithromycin and/or more antibiotic resistant strains in younger children.

Antibiotic resistance of Helicobacter pylori

Helicobacter pylori are spiral-shaped, Gram-negative bacteria that colonize the stomachs of more than half the world's population. H. pylori colonization is the most common cause of chronic active gastritis and peptic ulcer disease, which directly related to gastric carcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. However, the efficacies of eradication therapies are not satisfying mainly because of bacterial resistance to antibiotics. This article makes a brief summary on the recent research related to the antibiotic resistance of H. pylori.

Prevalence and evolution of Helicobacter pylori resistance to 6 antibacterial agents over 12 years and correlation between susceptibility testing methods

The aim of this study was to evaluate Helicobacter pylori antibacterial resistance in 2005 to 2007, resistance evolution since 1996 to 1999, and performance of breakpoint susceptibility testing (BST) compared with E test for clarithromycin or agar dilution method (ADM) for metronidazole, amoxicillin, tetracycline, and ciprofloxacin. Resistance in 613 untreated adults, 91 treated adults, and 75 untreated children was 25%, 48.4%, and 16% for metronidazole; 17.8%, 45.1%, and 18.7% for clarithromycin; 4.4%, 13.3%, and 2.7% for tetracycline; and 7.7%, 18.2%, and 6.8% for ciprofloxacin, respectively. Resistance to amoxicillin (0.9%) and nitrofurantoin (1.3%) was uncommon. Three strains (0.4%) exhibited triple resistance to amoxicillin, metronidazole, and clarithromycin. Primary resistance rates in adults and children were comparable. Metronidazole resistance was less common in ulcer adults than in the rest. Primary clarithromycin resistance increased significantly from 10% in 1996 to 1999 to 17.9% in 2005 to 2007. Many strains (26.4%) from treated adults showed resistance to metronidazole and clarithromycin. Category agreement between the BST and E test or ADM results was good (93.3-100%). In conclusion, the increasing clarithromycin resistance and presence of multidrug resistance are worrying. Fluoroquinolones should be used with caution for H. pylori eradication in treated patients.

Primary resistance in Helicobacter pylori isolated in children from Iran

Helicobacter pylori-associated infection is extremely common in Iran, as in other developing countries, but few data exist on the susceptibility of H. pylori to antimicrobials commonly used in the eradication schedules in this country. This study was performed to determine the resistance rate to six antimicrobial agents used in the treatment of H. pylori infection in dyspeptic Iranian children and to recommend an updated anti-H. pylori treatment regimen to use in children. All H. pylori isolated from children who were undergoing gastroscopy were prospectively collected and subcultured to yield their susceptibility to six antimicrobial agents, by E test and disk diffusion methods. Demographic data and presenting symptoms were also collected. A prospective study was carried out from January 2003 to January 2005 with 100 strains of H. pylori isolated from children (40 girls and 60 boys; age range, 1.5 to 16 years [mean, 9.22 +/- 3.25 years]); the strains had been successfully subcultured to yield antimicrobial sensitivity. Overall the H. pylori resistance rate was 95% to metronidazole, 59% to amoxicillin, 16% to clarithromycin, 9% to furazolidone, 7% to ciprofloxacin, and 5% to tetracycline. The most common presenting symptom was abdominal pain. There were no statistically significant differences in antimicrobial resistance rates related to age, sex, or clinical presentation. In the Iranian children, the prevalence of H. pylori resistance was very high to metronidazole and amoxicillin, moderate to clarithromycin, and low to ciprofloxacin and tetracycline.

The sequential therapy regimen for Helicobacter pylori eradication: a pooled-data analysis

BACKGROUND

Standard triple therapies are the most used treatment in clinical practice. However, a critical fall in the H pylori eradication rate following these therapies has been observed in the last few years. The sequential regimen is a novel, promising therapeutic approach.

OBJECTIVES

To evaluate the available data on the sequential therapy regimen.

METHODS

A pooled-data analysis of all studies on the sequential regimen was performed. The eradication rate was calculated according to gastroduodenal pathology, proton pump inhibitor used, antibiotic resistance, as well as setting (paediatric or geriatric patients). Compliance, side effects, and cost implications were also evaluated.

RESULTS

Overall, more than 1800 patients have been treated with the sequential regimen. Such a therapy was superior to 7-10 days triple therapies in paediatric, adult and elderly patients, achieving an eradication rate constantly higher than 90% at ITT analysis. Although primary clarithromycin resistance reduced the efficacy of such a therapy, a success rate significantly higher than that observed with the standard 7-10 days triple therapies was found.

CONCLUSION

The 10-day sequential treatment regimen achieves higher eradication rates than standard triple therapies.

Helicobacter pylori infection in pediatrics

During the last year, epidemiologic studies have shown that spontaneous clearance of Helicobacter pylori infection has a less significant role in countries with high prevalence and, in contrast to adults, there is no male predominance of H. pylori infection in children. Early acquisition of H. pylori may play a role in the development of recurrent abdominal pain in children less than 5 years of age. In this very young age group, the adequate performance of stool antigen test and (13)C urea-breath test demonstrated satisfactory sensitivity and specificity as non-invasive methods to diagnose H. pylori infection. In the current paper, the most relevant pediatric studies on H. pylori infection published between April 2006 and March 2007 are reviewed.

The sequential therapy regimen for Helicobacter pylori eradication: a pooled-data analysis

BACKGROUND

Standard triple therapies are the most used treatment in clinical practice. However, a critical fall in the H pylori eradication rate following these therapies has been observed in the last few years. The sequential regimen is a novel, promising therapeutic approach.

OBJECTIVES

To evaluate the available data on the sequential therapy regimen.

METHODS

A pooled-data analysis of all studies on the sequential regimen was performed. The eradication rate was calculated according to gastroduodenal pathology, proton pump inhibitor used, antibiotic resistance, as well as setting (paediatric or geriatric patients). Compliance, side effects, and cost implications were also evaluated.

RESULTS

Overall, more than 1800 patients have been treated with the sequential regimen. Such a therapy was superior to 7-10 days triple therapies in paediatric, adult and elderly patients, achieving an eradication rate constantly higher than 90% at ITT analysis. Although primary clarithromycin resistance reduced the efficacy of such a therapy, a success rate significantly higher than that observed with the standard 7-10 days triple therapies was found.

CONCLUSION

The 10-day sequential treatment regimen achieves higher eradication rates than standard triple therapies.

Role of sequential therapy in Helicobacter pylori eradication therapy

Evaluation of: Vaira D, Zullo A, Vakil N et al.: Sequential therapy versus standard triple-drug therapy for Helicobacter pylori eradication. A randomized trial. Ann. Intern. Med. 146, 556–563 (2007). The standard proton pump inhibitor-based triple-drug therapy to cure Helicobacter pylori infection fails in approximately 20% of patients. Antimicrobial resistance is significantly decreasing the eradication rates worldwide. This article evaluates whether sequential treatment is more effective than standard triple-drug therapy in a randomized, double-blind, placebo-controlled trial. The sequential regimen includes pantoprazole and amoxicillin (standard doses), each administered twice daily for the first 5 days, followed by the triple therapy of pantoprazole, clarithromycin and tinidazole (standard doses), each administered twice daily for the remaining 5 days. The results confirm that sequential therapy is more effective than standard therapy for eradicating H. pylori infection, mainly in patients with clarithromycin-resistant strains. Tolerance and compliance are similar with both treatments. These encouraging results should ideally be confirmed in other countries in larger cohorts. However, in the event of sequential therapy faliure, the effectiveness of the standard in dual clarithromycin and metronidazole resistance needs to be clarified.

Oral vaccination with liposome-encapsulated recombinant fusion peptide of urease B epitope and cholera toxin B subunit affords prophylactic and therapeutic effects against H. pylori infection in BALB/c mice

A new fusion peptide CtUBE of cholera toxin B subunit and Helicobacter pylori urease B subunit epitope was expressed in Escherichia coli. With this fusion peptide, an oral liposome vaccine against H. pylori infection was prepared and evaluated in BALB/c mice. Based on the results of urease tests, quantitation of culturable bacteria colonies in mice stomachs and histological identification of gastritis, the mice were protected significantly after intragastric vaccination with this CtUBE liposome vaccine, which increased the content levels of specific anti-urease serum IgG and mucosal IgA for both prophylactic and therapeutic vaccination protocols. These results showed that the fusion peptide CtUBE retained immunogenicity and could be used as antigen in the development of an oral vaccine against H. pylori infection.

Eradication therapy for Helicobacter pylori

Eradication therapy for Helicobacter pylori is recommended in a number of clinical conditions. In this article, we discuss the epidemiology and cellular mechanisms that result in antimicrobial resistance, the results of current eradication therapies, and new approaches to the management of Helicobacter pylori infection.

Helicobacter pylori primary resistant strains over 11 years in French children

The yearly prevalence between 1994 and 2005 of primary resistance to amoxicillin, metronidazole, and clarithromycin of 377 Helicobacter pylori strains isolated from children was studied. All the H. pylori strains were susceptible to amoxicillin, 138/377 (36.7%) were resistant to metronidazole, 86/377 (22.8%) to clarithromycin, and 30/377 (7.9%) to both metronidazole and clarithromycin. Over the entire period, resistance to clarithromycin did not change, whereas metronidazole resistance decreased significantly from 43.3% (1994-1998) to 32% (1999-2005), P = 0.001.

Immunology of Helicobacter pylori: insights into the failure of the immune response and perspectives on vaccine studies

Helicobacter pylori infects the stomach of half of the human population worldwide and causes chronic active gastritis, which can lead to peptic ulcer disease, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. The host immune response to the infection is ineffective, because the bacterium persists and the inflammation continues for decades. Bacterial activation of epithelial cells, dendritic cells, monocytes, macrophages, and neutrophils leads to a T helper cell 1 type of adaptive response, but this remains inadequate. The host inflammatory response has a key functional role in disrupting acid homeostasis, which impacts directly on the colonization patterns of H pylori and thus the extent of gastritis. Many potential mechanisms for the failure of the host response have been postulated, and these include apoptosis of epithelial cells and macrophages, inadequate effector functions of macrophages and dendritic cells, VacA inhibition of T-cell function, and suppressive effects of regulatory T cells. Because of the extent of the disease burden, many strategies for prophylactic or therapeutic vaccines have been investigated. The goal of enhancing the host's ability to generate protective immunity has met with some success in animal models, but the efficacy of potential vaccines in humans remains to be demonstrated. Aspects of H pylori immunopathogenesis are reviewed and perspectives on the failure of the host immune response are discussed. Understanding the mechanisms of immune evasion could lead to new opportunities for enhancing eradication and prevention of infection and associated disease.

Primary antibiotic resistance in Helicobacter pylori strains isolated in northern and central Italy

BACKGROUND

Helicobacter pylori resistance to antibiotics is increasing worldwide, and it reduces the efficacy of therapy.

AIM

To assess current primary antibiotic resistance in H. pylori strains isolated in Italy.

METHODS

Between June 2004 and June 2006, H. pylori strains were isolated consecutively in the two participating centres (Bologna, northern Italy; Rome, central Italy) from patients never previously treated for the infection. Isolated strains were tested for primary clarithromycin, metronidazole and levofloxacin resistance using as break point the minimal inhibitory concentration >/=1, >/=8 and >/=1 mg/L for the three antibiotics, respectively.

RESULTS

Overall, 255 H. pylori strains were evaluated. The resistance rate was 16.9% for clarithromycin, 29.4% for metronidazole and 19.1% for levofloxacin. Clarithromycin resistance was significantly higher in non-ulcer dyspepsia than in peptic ulcer patients (19.1% vs. 0%, P = 0.02), metronidazole resistance was higher in foreign than Italian patients (50% vs. 22.9%, P = 0.0004) and levofloxacin resistance was higher in old than younger patients (28.4% vs. 14.4%, P = 0.048). Levofloxacin resistance was also more frequent in those strains with either clarithromycin or metronidazole resistance.

CONCLUSION

A very high rate of primary resistance towards the tested antibiotics was detected in our study.

Progress in vaccine development against Helicobacter pylori

Based on the very high prevalence of diseases caused by Helicobacter pylori, particularly in the developing world, and the rapid emergence of antibiotic resistance among clinical isolates, there is a strong rationale for an effective vaccine against H. pylori. In this review we describe recent promising candidate vaccines and prophylactic or therapeutic immunization strategies for use against H. pylori, as well as studies to identify immune responses that are related to protection in experimental animals. We also describe identification of different types of immune responses that may be related to protection against symptoms based on comparisons of H. pylori-infected patients with duodenal ulcers or gastric cancer and asymptomatic carriers. We conclude that there is still a strong need to clarify the main protective immune mechanisms against H. pylori as well as to identify a cocktail of strong protective antigens, or recombinant bacterial strains that express such antigens, that could be administered by a regimen that gives rise to effective immune responses in humans.

Results from the pediatric European register for treatment of Helicobacter pylori (PERTH)

BACKGROUND AND AIM

Data on the eradication treatment for childhood Helicobacter pylori are scanty. A register was established on the European Society for Pediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) website to collect data on treatment performed by European pediatricians to ascertain what is practiced in the field.

SUBJECTS

From January 2001 to December 2002, information on 597 children were entered by 23 European Centers, but only data of 518 treated children were completed and analyzed (86.7%, 262 male subjects, median age 9 years, range 1-14). According to their nationality, 226 children were from Southern Europe, 132 from Eastern Europe, 68 from Western Europe, and 4 from northern Europe, 68 from North Africa, and 20 from Asia. At endoscopy, 454 children had gastritis and 64 had ulcer (12.3%). Antibiotic sensitivity, tested in 361 cases, revealed 18% clarithromycin-resistant and 19% metronidazole-resistant H. pylori strains.

RESULTS

Treatment was performed for 1 week in 388 and for 2 weeks in 130 children. Antibiotics were associated with proton pump inhibitors (PPI) in 345 and with bismuth in 121 children. Triple therapy was given to 485 children, dual therapy to 26, quadruple to 7. Follow-up data, by (13)C-Urea-Breath Test or histology or both, were available for 480 children. Overall eradication rate was 65.6%, significantly higher in children with ulcer (79.7%) than without (63.9%, p = .001). When given as first treatment, bismuth-containing triple therapies were more efficacious than PPI-containing ones (77% versus 64%, p = .02, OR 1.88, 95% CI 1.1-3.3). Twenty-seven different treatment regimens were used, but only six were administered to at least 18 children (range 18-157). There was no difference between treatments given for 1 or 2 weeks, or given as first or second therapies.

CONCLUSION

European pediatricians entering data in the register used 27 different regimens. Bismuth-containing therapies resulted in higher eradication rate. Omeprazole-containing triple therapies were the most used although their efficacy was low. Therapies recommended for adults do not appear to be suitable for children.

Helicobacter pylori detection and antimicrobial susceptibility testing

The discovery of Helicobacter pylori in 1982 was the starting point of a revolution concerning the concepts and management of gastroduodenal diseases. It is now well accepted that the most common stomach disease, peptic ulcer disease, is an infectious disease, and all consensus conferences agree that the causative agent, H. pylori, must be treated with antibiotics. Furthermore, the concept emerged that this bacterium could be the trigger of various malignant diseases of the stomach, and it is now a model for chronic bacterial infections causing cancer. Most of the many different techniques involved in diagnosis of H. pylori infection are performed in clinical microbiology laboratories. The aim of this article is to review the current status of these methods and their application, highlighting the important progress which has been made in the past decade. Both invasive and noninvasive techniques will be reviewed.

Clarithromycin resistance in Helicobacter pylori strains isolated from French children: prevalence of the different mutations and coexistence of clones harboring two different mutations in the same biopsy

BACKGROUND

The aim of our study was to assess the different mutations involved in clarithromycin-resistant Helicobacter pylori strains isolated from French children and their temporal trends.

METHODS

The point mutations of H. pylori were detected by PCR followed by RFLP technique in 50 clarithromycin-resistant strains collected between 1993 and 2004 in France.

RESULTS

Clarithromycin resistance was observed in 23% (50/217) of H. pylori isolates. Two mutations A2143G and A2142G in the 23S rRNA genes of H. pylori were detected. The former was found in 45/50 (90%) of isolates. The rate of resistance increased with time from 18.6% in the period 1993-1996 to 41.6% in 2001-2004. No significant difference was observed in the distribution of mutations during the same periods. No correlation was found between any mutation and age, sex, and ethnic origin of children. Furthermore, no significant differences in minimal inhibitory concentrations level were observed according to the different point mutations. In all cases, only one point mutation was present, except in two cases where two different mutations were found in two different clones from the same biopsy.

CONCLUSION

The mutation A2143G is predominant in clarithromycin-resistant H. pylori strains isolated from children in France. We report for the first time the presence of two clarithromycin-resistant clones harboring two different mutations of the 23S rRNA genes present in the same biopsy specimen and genotypically identical as demonstrated by RAPD fingerprinting.

How to proceed in Helicobacter pylori-positive chronic gastritis refractory to first- and second-line eradication therapy

Helicobacter pylori is a widespread disease causing most of the peptic ulcer diseases and low-grade mucosa-associated lymphoreticular tissue (MALT) lymphoma. Moreover, H. pylori is a proven environmental risk factor for gastric carcinoma and it has been recognized as a type 1 carcinogen factor. A combination of drugs has been proposed, using a proton pump inhibitor (PPI), amoxicillin, clarithromycin, metronidazole and tetracycline to treat the infection. Since 1996, according to the European guidelines, the first-line approach using PPI, amoxicillin and clarithromycin or metronidazole has been suggested. Seven days of quadruple therapy with PPI (or ranitidine), tetracycline, bismuth salts and metronidazole has been reserved as second-line treatment. To improve the eradication rate of the triple therapy, a different combination of the available antibiotics has been proposed, consisting of a 10-day sequential regimen. A second-line levofloxacin-amoxicillin-based triple therapy given for 10 days has been proposed, obtaining a high eradication rate, suggesting this regimen to be a suitable retreatment option in eradication failure. A third-line treatment with rifabutin-based regimen has been proposed.

Treatment of Helicobacter pylori infection

In clinical practice the recommended treatment regimens achieve only an 80%Helicobacter pylori eradication rate and this rate is lower in patients who have failed first-line treatment. The increasing indications for H. pylori treatment (idiopathic thrombocytopenia and iron deficiency anemia) and an increasing trend of antibiotic resistance (especially in southern Europe) emphasize the need for more effective H. pylori eradication. Smoking and a short duration of treatment, especially in patients with functional dyspepsia, are predictors of eradication failure. In first line, the best option remains the clarithromycin-based regimens but an extended treatment duration is now indicated. Following first-line treatment failure, 14-day proton pump inhibitor triple therapy employing alternative antibiotics or quadruple therapy could be used. Levofloxacin-based 10-day triple therapy seems to be an encouraging strategy following one or more eradication failures.

Helicobacter pylori infection in pediatrics

This review summarizes the literature on Helicobacter pylori infection in childhood between April 2005 and March 2006, and includes guidelines of the Canadian Helicobacter Study Group Consensus Conference, noninvasive tests, optimum therapy regimens and problems with resistance, and reviews on immune mechanisms in the gastric mucosa that may lead to the development of an effective vaccine.