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

Investigation of multidrug-resistant Helicobacter pylori in pediatric patients: A Bulgarian study and literature data

Antibiotic resistance of Helicobacter pylori strains from 106 symptomatic children was evaluated according to EUCAST breakpoints and rate of multidrug resistance (MDR) was analyzed. Overall resistance rates were amoxicillin 7.5%, metronidazole 25.5%, clarithromycin 34.0% and ciprofloxacin 14.1%. There were no significant differences in resistance rates according to patients' age (2-6 and 7-18 years) and sex. Combined resistance rate was 19.8%, including double, triple, and quadruple resistance in 13.2% (14 strains), 5.7% (6) and 0.9% (1) of the strains, respectively. MDR was found in 5.9% (5/84) of the children with gastritis and in two of the four children with celiac disease. The MDR was present in three children aged 4-6 years and in four children aged 10-17 years. The total MDR rate (6.6%) in Bulgarian children in 2012-2021 was higher than those in other studies based on EUCAST breakpoints such as those in pediatric patients in Slovenia in 2011-2014 (3.8%), Lithuania in 2013-2015 (0%) and Spain in 2014-2019 (0%), although being lower than those (20.7% in the untreated and 47.0% in the treated children) in China in 2019. In brief, it is of concern that MDR can strongly limit the choice of H. pylori therapy of one out of fifteen Bulgarian children and that overall resistance to both metronidazole and clarithromycin can hinder the treatment of 15.1% of the pediatric patients. Susceptibility-guided tailored eradication therapy of H. pylori infection should be more frequently implemented in the symptomatic children to avoid risks of both the infection itself and multiple antibiotic treatments.

Helicobacter pylori infection is associated with anemia, weight loss or both conditions among Bulgarian children

Some studies suggested an association between Helicobacter pylori infection and iron-deficiency anemia, however, the link between weight loss and the infection in childhood remains non-established. In a retrospective cohort study, we compared H. pylori positivity rates of Bulgarian children without or with anemia (47 children in each group) or weight loss (45 children in each group) and both conditions (17 children in each group). H. pylori infection was associated with the presence of anemia (in 76.6% of the anemic vs. 21.3% of the non-anemic patients, P < 0.0001) and weight loss (in 82.2% of the patients vs. 17.8% of the control children, P < 0.0001). All 17 patients with both conditions were H. pylori positive. Relative risk of anemia, weight loss and both conditions was 3.6 (95% CI, 2.0-6.4), 4.6 (95% CI, 2.4-8.8) and 5.7 (95% CI, 2.0-15.8), respectively, in the children with H. pylori infection. In conclusion, H. pylori infection was significantly associated with iron-deficiency anemia or/and weight loss in Bulgarian pediatric patients. Therefore, diagnostics and treatment of the infection as well as a proper control of the eradication success can be beneficial and thus, can be recommended for children with those conditions.

Sociodemographic characteristics and clinical risk factors of Helicobacter pylori infection and antibiotic resistance in the Eastern Black Sea region of Turkey

BACKGROUND/AIMS

The aim of this study was to assess the clinical and sociodemographic risk factors of Helicobacter pylori infection and antibiotic resistance in the eastern Black Sea region of Turkey.

MATERIALS AND METHODS

In total, 344 patients with dyspeptic symptoms who completed an extended questionnaire were enrolled in the study. Diagnosis of H. pylori infection was made by rapid urease test, histopathological investigation, and culture. Susceptibility of H. pylori strains was assessed by agar dilution (amoxicillin, tetracycline, metronidazole, levofloxacin) and E-test (clarithromycin) methods.

RESULTS

The H. pylori positivity rate was 40.4% (139/344). Logistic regression analysis indicated that age and the presence of duodenal ulcer were independent risk factors associated with H. pylori positivity (odds ratio (OR): 0.96, 95% CI: 0.93-0.99, p=0.013; OR: 5.42, 95% CI: 1.96-14.98, p=0.001, respectively). Of 104 H. pylori-positive cultures, 43 strains (41%) were susceptible to all antibiotics, whereas 61 (59%) were resistant to at least one antibiotic. H. pylori resistance rates were 34% for levofloxacin, 31.1% for metronidazole, 28.2% for clarithromycin, 2.9% for amoxicillin, and 1% for tetracycline. Logistic regression analysis indicated that previous use of clarithromycin was the only independent risk factor for H. pylori resistance (OR: 6.25, 95% CI: 1.59-24.52, p=0.009).

CONCLUSION

An understanding of the risk factors for H. pylori positivity and antibiotic resistance in an extended anamnesis may affect treatment choice and facilitate H. pylori eradication. In regions where antibiotic resistance rates are elevated, performing antibiotic susceptibility tests may lead to effective eradication treatment.

Prevalence of Helicobacter pylori is still high among symptomatic Bulgarian children

Helicobacter pylori positivity was assessed among 656 symptomatic children in 2010-2017. Overall infection prevalence was 24.5% and a significantly higher rate was detected in girls (28.5%) compared to boys (20.0%). Moreover, in children with duodenal ulcer, H. pylori prevalence was higher (47.4%) compared with the rest (23.9%). On the contrary, the infection was detected 1.9-fold less frequently in patients with GERD (14.5%) compared with the other (27.0%) patients and 2.1-fold less often in the presence of duodenogastric reflux (bile) reflux (13.0%) compared with the absence of the reflux (27.0%). No significant difference was observed between the younger (aged ≤7 years, 20.0%) and the older (aged 8-18 years, 25.5%) patients. H. pylori infection rate in Bulgarian pediatric patients between 2010 and 2017 was 2.5-fold lower than that in 1996-2006. In conclusion, H. pylori infection is still an important concern for Bulgarian children, although having decreased by about 1.8%/yearly over 21 years. This study reveals the importance of H. pylori diagnostics even in the youngest symptomatic children and demonstrates an inverse association between either GERD or bile reflux and H. pylori infection.

Genetic basis for metronidazole and clarithromycin resistance in Helicobacter pylori strains isolated from patients with gastroduodenal disorders

BACKGROUND

The aim of this study was to evaluate the antimicrobial resistance and genetic basis for metronidazole (Mtz) and clarithromycin (Cla) resistance in strains of Helicobacter pylori, isolated from patients with gastroduodenal disorders.

PATIENTS AND METHODS

A total of 157 H. pylori isolates (from 22 gastric cancer, 38 peptic ulcer disease, and 97 non-ulcer dyspepsia patients) were analyzed for drug susceptibility to Mtz and Cla, by gradient diffusion test (E-test, MAST). The PCR and sequence analysis of the rdxA and frxA for Mtz-resistant strains and the 23S rRNA for Cla-resistant strains were used to determine the genetic basis of drug resistance in H. pylori strains. Increased expression of TolC homologous genes (hefA) that upregulates efflux pump activity was determined in multidrug-resistant (MDR) strain of H. pylori by real-time PCR technique.

RESULTS

Among 157 H. pylori isolates, 32 (20.4%) strains were resistant to at least one of the antimicrobial agents. The highest resistance rate was attributed to Mtz (n=69, 43.94%). Among the resistant strains of H. pylori, 15 cases (9.55%) were detected as MDR. Mutations in the rdxA (85.5%) and A2143G point mutations (63.1%) in the 23S rRNA were the most common cause of resistance to Mtz and Cla in strains of H. pylori, respectively. In MDR strains, the rdxA mutation and A2143G-point mutation in the 23S rRNA were the most abundant mutations responsible for drug resistance. The relative expression of hefA in MDR strains (mean 3.706) was higher than the susceptible strains (mean 1.07).

CONCLUSION

Mutational inactivation and efflux pump overexpression are two mechanisms that increase the resistance to H. pylori antimicrobial agents and the rate of MDR strains. In Iran, the mutations of rdxA and frxA in Mtz-resistant strains and A2143G and A2142G of the 23S rRNA in Cla-resistant strains were significant. The screening for these mutations could help to prevent antibiotic resistance, and to determine the most effective anti-H. pylori drugs.

Prevalence of Antibiotic Resistance in Helicobacter pylori: A Systematic Review and Meta-analysis in World Health Organization Regions

BACKGROUND & AIMS

In 2017, the World Health Organization (WHO) designated clarithromycin-resistant Helicobacter pylori a high priority for antibiotic research and development. However, there are no clear data on the global distribution of resistance or its clinical effects. We performed a systematic review and meta-analysis to assess the distribution of H pylori resistance to commonly used antibiotics and to measure the association between antibiotic resistance and treatment failure.

METHODS

We searched publication databases for studies that assessed rates of H pylori resistance to clarithromycin, metronidazole, levofloxacin, amoxicillin, or tetracycline. Pooled estimates of primary and secondary resistance and 95% confidence intervals (CIs) were grouped by WHO region. The association between antibiotic resistance and treatment failure was measured by extracting data on treatment efficacy in patients with resistant and susceptible isolates and pooling odds ratios with 95% CIs.

RESULTS

We identified 178 studies, comprising 66,142 isolates from 65 countries. Primary and secondary resistance rates to clarithromycin, metronidazole, and levofloxacin were ≥15% in all WHO regions, except primary clarithromycin resistance in the Americas (10%; 95% CI, 4%-16%) and South-East Asia region (10%; 95% CI, 5%-16%) and primary levofloxacin resistance in the European region (11%; 95% CI, 9%-13%). There was considerable heterogeneity (I2 > 75%) among all analyses-this might have resulted from the grouping of resistance rates by country. Increasing antibiotic resistance was observed in most WHO regions. Resistance to clarithromycin was significantly associated with failure of clarithromycin-containing regimens (odds ratio, 6.97; 95% CI, 5.23-9.28; P < .001).

CONCLUSIONS

Resistance of H pylori to antibiotics has reached alarming levels worldwide, which has a great effect on efficacy of treatment. Local surveillance networks are required to select appropriate eradication regimens for each region.

Protective activity of geraniol against acetic acid and Helicobacter pylori- induced gastric ulcers in rats

Geraniol, an active constituent of rose and palmarosa essential oils, possesses several pharmacological properties, including antioxidant, antibacterial and antiulcer activity. Geraniol was therefore investigated for its antiulcer and anti-Helicobacter pylori activity in rats. Ulcers were induced by injecting acetic acid into the sub-serosal layer of the stomach followed by orogastric inoculation of H. pylori for 7 days. Geraniol (15 and 30 mg/kg), vehicle and a standard drug combination (amoxicillin, 50 mg/kg; clarithromycin, 25 mg/kg and omeprazole, 20 mg/kg) were administered twice daily for 14 days. All the parameters were measured at the end of treatment. The ulcer index was significantly (P < 0.05) lowered in geraniol and standard drug-treated rats as compared to the H. pylori control group (4.13 ± 0.43). Treatment with geraniol (30 mg/kg) significantly (P < 0.01) increased the gastric pH along with a reduction in total acidity and gastric juice volume. Geraniol significantly (P < 0.05) attenuated the myeloperoxidase activity and augmented the total glutathione level in gastric mucosa. The extent of damage in the stomach was measured using a histopathological score. The score in H. pylori control, geraniol (30 mg/kg) and standard drugs was 9, 3.5 and 2.0 respectively. In the rapid urease test, treatment with geraniol (30 mg/kg) and the standard drugs produced a 33% and 67% cure respectively from H. pylori infection. Further, the reduction in bacterial load in the gastric mucosa was confirmed using modified Giemsa staining. Geraniol was observed to exhibit significant antiulcer and anti-H. pylori activity in a rodent model.

World trends for H. pylori eradication therapy and gastric cancer prevention strategy by H. pylori test-and-treat

Helicobacter pylori-associated gastritis leads to the development of gastric cancer. Kyoto global consensus report on H. pylori gastritis recommended H. pylori eradication therapy to prevent gastric cancer. To manage H. pylori infection, it is important to choose the appropriate regimen considering regional differences in resistance to clarithromycin and metronidazole. Quinolones and rifabutin-containing regimens are useful as third- and fourth-line rescue therapies.

Bacteriocin-like inhibitory activities of seven Lactobacillus delbrueckii subsp. bulgaricus strains against antibiotic susceptible and resistant Helicobacter pylori strains

The aim of the study was to detect anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains by four cell-free supernatant (CFS) types. Activity of non-neutralized and non-heat-treated (CFSs1), non-neutralized and heat-treated (CFSs2), pH neutralized, catalase-treated and non-heat-treated (CFSs3), or neutralized, catalase- and heat-treated (CFSs4) CFSs against 18 H. pylori strains (11 of which with antibiotic resistance) was evaluated. All GLB strains produced bacteriocin-like inhibitory substances (BLISs), the neutralized CFSs of two GLB strains inhibited >81% of test strains and those of four GLB strains were active against >71% of antibiotic resistant strains. Two H. pylori strains were BLIS resistant. The heating did not reduce the CFS activity. Briefly, all GLB strains evaluated produced heat-stable BLISs, although GLB and H. pylori strain susceptibility patterns exhibited differences. Bacteriocin-like inhibitory substance activity can be an advantage for the probiotic choice for H. pylori infection control.

SIGNIFICANCE AND IMPACT OF THE STUDY

In this study, anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains was evaluated by four cell-free supernatant (CFS) types. The GLB strains produced heat-stable bacteriocin-like inhibitory substances (BLISs) with a strong anti-H. pylori activity and some neutralized, catalase- and heat-treated CFSs inhibited >83% of the test strains. Bacteriocin-like inhibitory substance production of GLB strains can render them valuable probiotics in the control of H. pylori infection.

Primary Helicobacter pylori resistance in elderly patients over 20 years: A Bulgarian study

We evaluated the antibiotic susceptibility of 233 Helicobacter pylori strains isolated in the period 2011-2016, involving 62 strains from elderly patients aged 66-93years and 171 strains from younger adults. To assess resistance evolution, primary resistance rates in 92 strains from as many patients aged ≥60years in 1996-2003 were compared with those in 85 strains from infected patients in the same age group in 2011-2016. In the patients aged >65years evaluated during the last 6 years, amoxicillin resistance according to EUCAST and prior breakpoints was 1.6 and 0%, respectively. Resistance rates were the same by both breakpoint systems to metronidazole (35.5%), clarithromycin (22.6%), tetracycline (1.6%) and levofloxacin (32.3%). In 2011-2016, there were no significant differences between resistance rates in the subjects aged >65years and the younger adults. Notably, during the last 6 years, double/triple resistance was found in 21.0% of the subjects aged >65years. Moreover, the prevalence of quinolone primary resistance (30.0%) was significantly (3.4-fold) higher than that (8.9%) observed in 1996-2003. Briefly, the presence of both combined resistance and a strikingly high primary levofloxacin resistance in the elderly implies a cautious antibiotic choice for H. pylori eradication. In vitro susceptibility testing of the strains is highly important in this age group. The results can be linked to more frequent comorbidities and co-infection treatment in older compared with younger patients and, additionally, to the national antibiotic consumption. The high prevalence of quinolone resistance in the elderly patients is an alarming finding.

Review article: the global emergence of Helicobacter pylori antibiotic resistance

BACKGROUND

Helicobacter pylori is one of the most prevalent global pathogens and can lead to gastrointestinal disease including peptic ulcers, gastric marginal zone lymphoma and gastric carcinoma.

AIM

To review recent trends in H. pylori antibiotic resistance rates, and to discuss diagnostics and treatment paradigms.

METHODS

A PubMed literature search using the following keywords: Helicobacter pylori, antibiotic resistance, clarithromycin, levofloxacin, metronidazole, prevalence, susceptibility testing.

RESULTS

The prevalence of bacterial antibiotic resistance is regionally variable and appears to be markedly increasing with time in many countries. Concordantly, the antimicrobial eradication rate of H. pylori has been declining globally. In particular, clarithromycin resistance has been rapidly increasing in many countries over the past decade, with rates as high as approximately 30% in Japan and Italy, 50% in China and 40% in Turkey; whereas resistance rates are much lower in Sweden and Taiwan, at approximately 15%; there are limited data in the USA. Other antibiotics show similar trends, although less pronounced.

CONCLUSIONS

Since the choice of empiric therapies should be predicated on accurate information regarding antibiotic resistance rates, there is a critical need for determination of current rates at a local scale, and perhaps in individual patients. Such information would not only guide selection of appropriate empiric antibiotic therapy but also inform the development of better methods to identify H. pylori antibiotic resistance at diagnosis. Patient-specific tailoring of effective antibiotic treatment strategies may lead to reduced treatment failures and less antibiotic resistance.

Three unsuccessful treatments of Helicobacter pylori infection by a highly virulent strain with quadruple antibiotic resistance

We report a case of an adult patient undergoing three unsuccessful Helicobacter pylori treatments, including proton pump inhibitor (PPI), bismuth subcitrate, metronidazole and tetracycline in 2012, PPI, amoxicillin and clarithromycin in 2013, and PPI, amoxicillin and rifampin in 2014. Following the first treatment, the isolate was metronidazole and ciprofloxacin/levofloxacin resistant. After the second treatment, the isolate was resistant to metronidazole, ciprofloxacin/levofloxacin and rifampin, developing secondary clarithromycin resistance by A2143G mutation and was susceptible only to tetracycline. After the third treatment, the patient still remained H. pylori positive. Patient's strain was highly virulent (cagA (+) , cagE (+) and vacA s1a/m1/i1). The evolution of the patient's disease was from gastroesophageal reflux disease in 2012 to two duodenal ulcers in 2015. Briefly, the infecting strain showed quadruple antibiotic resistance and a transient amoxicillin resistance. Triple clarithromycin-based treatment induced secondary clarithromycin resistance by A2143G mutation, while rifampin resistance caused the third treatment failure. Several options for the next treatment regimens are discussed.

Clarithromycin Resistance Mutations in Helicobacter pylori in Association with Virulence Factors and Antibiotic Susceptibility of the Strains

Antibiotic resistance is the major cause for Helicobacter pylori eradication failure. H. pylori clarithromycin resistance mutations were evaluated in 84 (82 phenotypically clarithromycin resistant and 2 intermediately susceptible) strains by allele-specific PCR and 3'-mismatched PCR. Many (57.1%) of these strains were metronidazole resistant. Prevalence of cagA(+), cagE(+), vacA s1a, m1, i1, and i2 strains was 76.2%, 58.0%, 82.1%, 35.7%, 50.0%, and 50.0%, respectively. A2143G, A2142G, A2142C, and A2143G+A2142G mutation rates were 64.3%, 23.8%, 1.2%, and 10.7%, respectively. Strains harboring the A2142G mutation showed 5.3-fold higher clarithromycin MIC50 than those harboring the A2143G mutation. The A2143G mutation alone was 1.7-fold more common in vacA i2 strains compared with vacA i1 strains, while the A2142G mutation alone was 3-fold more frequent in vacA i1 strains than vacA i2 strains and 3.1-fold more common in metronidazole-susceptible compared with metronidazole-resistant strains. Briefly, clarithromycin resistance mutations were significantly linked to vacA i allele and metronidazole susceptibility. This is the first report about associations between the A2143G mutation and less virulent vacA i2 strains, and between the A2142G mutation and more virulent vacA i1 strains. As the 2143G mutation often predicts eradication failure by clarithromycin-based regimens, the results may be linked to the better eradication of more virulent strains compared with the less virulent strains.

Linezolid susceptibility in Helicobacter pylori, including strains with multidrug resistance

Only a few studies have evaluated Helicobacter pylori susceptibility to linezolid. The aim of the present study was to assess linezolid susceptibility in H. pylori, including strains with double/multidrug resistance. The susceptibility of 53 H. pylori strains was evaluated by Etest and a breakpoint susceptibility testing method. Helicobacter pylori resistance rates were as follows: amoxicillin, 1.9%; metronidazole, 37.7%; clarithromycin, 17.0%; tetracycline, 1.9%; levofloxacin, 24.5%; and linezolid (>4 mg/L), 39.6%. The linezolid MIC50 value was 31.2-fold higher than that of clarithromycin and 10.5-fold higher than that of levofloxacin; however, 4 of 11 strains with double/multidrug resistance were linezolid-susceptible. The MIC range of the oxazolidinone agent was larger (0.125-64 mg/L) compared with those in the previous two reports. The linezolid resistance rate was 2.2-fold higher in metronidazole-resistant strains and in strains resistant to at least one antibiotic compared with the remaining strains. Briefly, linezolid was less active against H. pylori compared with clarithromycin and levofloxacin, and linezolid resistance was linked to resistance to metronidazole as well as to resistance to at least one antibiotic. However, linezolid activity against some strains with double/multidrug resistance may render the agent appropriate to treat some associated H. pylori infections following in vitro susceptibility testing of the strains. Clinical trials are required to confirm this suggestion.

Formulation and in vitro evaluation of size expanding gastro-retentive systems of levofloxacin hemihydrate

Size increasing (plug-type) levofloxacin hemihydrate (LVF) tablets for eradication of Helicobacter pylori (H. pylori) were prepared using in situ gel forming polymers including: gellan gum, sodium alginate, pectin and xanthan gum. Effect of cross-linkers: calcium and aluminum chloride, on the drug release was also studied. The prepared tablets were evaluated for their physicochemical parameters: weight variation, thickness, friability, hardness, drug content, water uptake and in vitro drug release. The optimized formula was subjected to further studies such as radial swelling test, FT-IR and DSC. Results revealed that LVF release depends not only on the nature of the matrix but also on the type of cross linker used to form this polymeric matrix. The addition of either calcium chloride or aluminum chloride, as cross-linkers, to gellan gum formulations significantly decreased drug release. Other polymers' formulations resulted in increased drug release upon addition of the same cross-linkers. The formula containing xanthan gum without any cross linker showed the most sustained LVF release with an increase in diameter with time, thus acting as a plug-type dosage form. IR spectra and DSC thermograms of LVF, xanthan gum, and a physical mixture of both, indicated that there was no interaction between the drug and the polymer and confirmed the drug stability.

In vitro activity of Aloe vera inner gel against Helicobacter pylori strains

Aloe barbadensis Miller (Aloe vera) is a herbal remedy widely used for a variety of illnesses; A. vera leaf extracts have been promoted for detoxification, cure constipation, help flush out toxins and wastes from the body, promote digestion and are used in the treatment of peptic ulcer for cytoprotective action. The aim of this study was to evaluate the antibacterial activity of A. vera inner gel against both susceptible and resistant Helicobacter pylori strains isolated in Abruzzo region, Italy. The inner gel of leaves of a 5-year-old plant of A. vera was extracted, homogenized and tested from 800 to 1.56 mg ml(-1) against 14 clinical strains and one reference strain of H. pylori using the broth microdilution methodology. Furthermore, the sample of A. vera was investigated for the chemical fingerprint of anthraquinones. The inhibitory concentrations of A. vera inner gel were similar to the bactericidal ones, with values ranging from 6.25 to 800 mg ml(-1) . Fifty per cent of the detected strains, independently of their susceptibility profile, were inhibited in their growth at 100 mg ml(-1) . Aloe vera inner gel expresses antibacterial properties against H. pylori and, therefore, in combination with antibiotics, could represent a novel strategy for the treatment of the infection of H. pylori, especially in cases of multiresistance.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study demonstrates that the Aloe vera inner gel expresses antibacterial properties against both susceptible and resistant Helicobacter pylori strains. These findings may impact on the antimicrobial resistance phenomenon of H. pylori, proposing the A. vera inner gel as a novel effective natural agent for combination with antibiotics for the treatment of H. pylori gastric infection.

Comparative evaluation of the activity of plant infusions against Helicobacter pylori strains by three methods

The aim of the study was to assess the activities of six plant infusions against Helicobacter pylori strains using a comparative screening assay (CSA), agar-well diffusion method (AWDM) and microscopy. Green tea, St John's wort (SJW), rooibos, peppermint, chamomile and lime flower aqueous infusion concentrations were chosen to mimic those in herbal teas/tisanes. CSA concentrations were 4.5 mg ml⁻¹ for chamomile and 6.8 mg ml⁻¹ for the other agents. AWDM amounts were 0.4 mg/well for the chamomile and 0.6 mg/well for the other agents. Using CSA, ≥8 × 10⁴ colony forming unit reduction was found in >60 % of the strains by the green tea (81.5 %), SJW (75.9 %) and rooibos (63.0 %) within 2 h. Similarly, by AWDM, the activity against >60 % of the strains was found by the green tea, SJW and rooibos. Gram staining results were alike, showing mostly/only coccoids in >66 % of the strains by the same three agents within 2 h. Lime flowers showed the lowest activity by all methods. In conclusion, CSA allows comparing the activities of many agents against numerous strains. To our knowledge, these are the first data about rooibos and lime flower activities against H. pylori. All the three methods revealed that the most active agents were the green tea, SJW and rooibos, which also possess additional beneficial properties, e.g. antioxidant, anti-inflammatory and antitumor effects, therefore these plants may have a beneficial use as prophylactic agents against or adjuvants in the therapy of H. pylori infection.

How antibiotic resistances could change Helicobacter pylori treatment: A matter of geography?

Therapeutic management of Helicobacter pylori (H. pylori) remains an unsolved issue. Indeed, no therapeutic regimen is able to cure the infection in all treated patients, and in many the infection persists despite the administration of several consecutive standard therapies. Although antibiotic resistance reports describe alarming results, the outcome of therapeutic regimens does not seem to parallel this scenario in most cases, since a successful performance is often reached in more than 80% of cases. However, the phenomenon of increasing antibiotic resistance is being closely studied, and the results show controversial aspects even in the same geographic area. For the continents of Europe, America, Asia, Africa, and Oceania, minimal and maximal values of resistance to the main antibiotics (clarithromycin, amoxicillin, metronidazole, and levofloxacin) feature wide ranges in different countries. The real enigma is therefore linked to the several different therapeutic regimens, which show results that often do not parallel the in vitro findings even in the same areas. A first aspect to be emphasized is that some regimens are limited by their use in very small geographic districts. Moreover, not all therapeutic trials have considered bacterial and host factors affecting the therapeutic outcome. The additional use of probiotics may help to reduce adverse events, but their therapeutic impact is doubtful. In conclusion, the “ideal therapy”, paradoxically, appears to be a “utopia”, despite the unprecedented volume of studies in the field and the real breakthrough in medical practice made by the discovery and treatment of H. pylori. The ample discrepancies observed in the different areas do not encourage the development of therapeutic guidelines that could be valid worldwide. On these bases, one of the main challenges for the future might be identifying a successful solution to overcome antibiotic resistances. In this context, geography must be considered a relevant matter.

Characterization of oral Helicobacter pylori strain by 4 methods

The aim of the study was to describe oral Helicobacter pylori strain from a child by 4 methods. The strain was positive by immunofluorescence, ureA- and cagA positive, vacA s1 m2 genotype and resistant to metronidazole and clarithromycin. In conclusion, virulent and antibiotic resistant H. pylori strains can be present in oral cavity from patients with chronic dental and gastroduodenal diseases.

Progress in research of Helicobacter pylori efflux pumps

The wide use and abuse of antibiotics have led to serious drug resistance of Helicobacter pylori (H. pylori), and strains simultaneously resistant to metronidazole, clarithromycin and amoxicillin have appeared. As a result, the rate of H. pylori eradication declines clinically. The presence of bacterial efflux pumps is an important mechanism responsible for bacterial resistance to most antibiotics, especially multiple drug resistance (MDR). In recent years, much attention has been paid to the research of efflux pumps and their inhibitors to solve the problem of drug resistance of H. pylori. In this paper we will introduce main efflux pumps and efflux pump inhibitors in H. pylori.

Living in Sofia is associated with a risk for antibiotic resistance in Helicobacter pylori: a Bulgarian study

The aim of the retrospective study was to evaluate geographic regions and residence places as possible risk factors for primary Helicobacter pylori antibiotic resistance in Bulgaria. Data from Sofia region, exhibiting the highest living density, were compared to those from other residence places. In total, 588 H. pylori strains from untreated adults who filled a questionnaire were evaluated. Strain susceptibility was assessed by a breakpoint susceptibility test. Resistance rates to metronidazole and clarithromycin have been found to increase, and that to tetracycline has been found to decrease over years. Clarithromycin resistance was 1.7-fold higher in Sofia inhabitants (23.5 %) than elsewhere (13.8 %) and 4.7-fold higher than that in villages (5.0 %). Moreover, the clarithromycin resistance rate was 2.6-fold lower in northern region (8.2 %) than in southern region (21.7 %). On multivariate analysis, sex and residence place were independent predictors for metronidazole resistance. Men were at lower risk for metronidazole resistance compared with women [odds ratio (OR) 0.703; 95 % confidence interval (CI) 0.499-0.990]. Importantly, Sofia inhabitants were at higher risk for the resistance compared with those living elsewhere (OR 1.453; 95 % CI 1.009-2.093). In conclusion, living in Sofia was associated with a risk for antibiotic resistance in H. pylori-positive adults. Living density could be associated with H. pylori resistance rates.

Helicobacter pylori eradication in Western Australia using novel quadruple therapy combinations

BACKGROUND

Helicobacter pylori eradication rates with standard triple therapy are declining worldwide. The optimal management of H. pylori is evolving and new treatment combinations for antibiotic resistant H. pylori strains are required, especially for patients with penicillin allergy.

AIM

To review the effectiveness of alternative antibiotic combinations and necessity of pre-antibiotic sensitivity testing.

METHODS

A total of 310 consecutive patients who had failed at least one course of standard 7-day triple therapy initially prescribed by their physicians were included in this study between year 2007 and 2011. Antibiotics were prescribed based on pre-antibiotic sensitivity tests and, if any, patient's allergy to penicillin.

RESULTS

In 98.7% of the patients' samples, H. pylori was successfully cultured. The proportion resistant to clarithromycin and metronidazole was 94.1% and 67.6% respectively, with 65% resistant to both. For the in-house primary quadruple therapy, with Proton pump inhibitor, Amoxicillin, Rifabutin and Ciprofloxacin (PARC), H. pylori was successfully eradicated in 95.2% of patients. For patients allergic to amoxicillin, an alternative quadruple therapy using Proton pump inhibitor, Bismuth subcitrate, Rifabutin and Ciprofloxacin (PBRC) gave an eradication rate of 94.2%. Patients needing alternative salvage therapy were given novel personalised combinations consisting of bismuth, rifabutin, tetracycline or furazolidone; the eradication rate was 73.8%.

CONCLUSIONS

Patients who present with antibiotic resistant H. pylori can be confidently treated with PARC, PBRC or other personalised salvage therapies. These regimens can be used when treatment options are limited by penicillin allergy. Pre-treatment H. pylori antibiotic sensitivity tests contributed to the high eradication rate in this study.

Primary resistance of Helicobacter pylori to levofloxacin and moxifloxacine in Iran

The increase in the prevalence of antibiotic resistance in Helicobacter pylori had a drastic effect on successful treatment. Up-to-date information on H. pylori antibiotic therapy in Iran is still limited. In this study, we aim to determine the prevalence of antibiotic resistance among the H. pylori strains. Furthermore, the possibility of using fluoroquinolones for antibiotic treatment was investigated. Antral biopsy specimens obtained from dyspeptic patients were investigated for H. pylori. Bacterial culture and susceptibility tests were done based on standard methods. H. pylori ATCC 43504 was used as a quality control. In the current study, 30 H. pylori strains were selected randomly and retested to confirm our susceptibility tests. Of 170 patients, 150 were identified as positive for H. pylori (88.2%). In this study, 150 single colonies of H. pylori strains [81 women (54%), 69 men (46%); mean age 38.6; aged 21-70 years] were collected. Primary resistance of H. pylori isolates were clarithromycin (34%), metronidazole (78.6%), tetracycline (9.3%), amoxicillin (10%), levofloxacin (5.3%) and moxifloxacine (4.6%). In conclusion, our results show that we are confronting a new generation of resistant strains of H. pylori in Iran. This alarming finding indicates an urgent need for introduction of new effective antibiotics in our country. Since the majority of clinicians prefer to continue with the ineffective antibiotics as therapeutic regimens, they must also be prepared to deal with treatment failures.

Significance of Helicobacter pylori vacA intermediate region genotyping-a Bulgarian study

The significance of the intermediate (i) region of the Helicobacter pylori vacA gene as a virulence factor associated with the severity of gastric disease is still disputable. The aim of the present study was to evaluate the prevalence and significance of vacA i alleles alone or in combination with other vacA alleles in symptomatic Bulgarian patients and to find out possible associations between vacA i genotype and patients' disease, age, sex, and other H. pylori virulence factors. Unlike vacA s1 and m1, vacA i1 prevalence was significantly higher (75.0%) in strains from peptic ulcer patients than in strains from nonulcer patients with gastric diseases (58.6%) (P = 0.022). Less virulent vacA s1 i2 m2 strains were more prevalent in females (P = 0.03), and cagA(+) was associated with vacA i1, s1, m1, and their combinations. In conclusion, vacA i status is a better predictor for the strain virulence than other vacA alleles.

Quadruple therapy with moxifloxacin and bismuth for first-line treatment of Helicobacter pylori

AIM: To compare triple therapy vs quadruple therapy for 10 d as first-line treatment of Helicobacter pylori (H. pylori) infection.

METHODS: Consecutive H. pylori positive patients never treated in the past for this infection were randomly treated with triple therapy of pantoprazole (PAN) 20 mg bid, amoxicillin (AMO) 1 g bid and moxifloxacin (MOX) 400 mg bid for 10 d (PAM) or with quadruple therapy of PAN 20 mg bid, AMO 1 g bid, MOX 400 mg bid and bismuth subcitrate 240 mg bid for 10 d (PAMB). All patients were found positive at 13 C-Urea breath test (UBT) performed within ten days prior to the start of the study. A successful outcome was confirmed with an UBT performed 8 wk after the end of treatment. χ² analysis was used for statistical comparison. Per protocol (PP) and intention-to-treat (ITT) values were also calculated.

RESULTS: Fifty-seven patients were enrolled in the PAM group and 50 in the PAMB group. One patient in each group did not return for further assessment. Eradication was higher in the PAMB group (negative: 46 and positive: 3) vs the PAM group (negative: 44 and positive: 12). The H. pylori eradication rate was statistically significantly higher in the PAMB group vs the PAM group, both with the PP and ITT analyses (PP: PAMB 93.8%, PAM 78.5%, P < 0.02; ITT: PAMB 92%, PAM 77.1 %, P <0.03).

CONCLUSION: The addition of bismuth subcitrate can be considered a valuable adjuvant to triple therapy in those areas where H. pylori shows a high resistance to fluoroquinolones.

Monitoring of antibiotic resistance rates of Helicobacter pylori in Austrian children, 2002-2009

We retrospectively studied antibiotic resistance rates of H. pylori and their temporal changes in children. Resistance rates were 21.6% for both clarithromycin and metronidazole. There was no overall difference between children with or without migrational background. Resistance rates increased over time, and patients without migrational background showed a significant increase in metronidazole resistance. Our study emphasizes antibiotic resistance monitoring of H. pylori in children.

Primary and secondary clarithromycin, metronidazole, amoxicillin and levofloxacin resistance to Helicobacter pylori in southern Poland

The aim of this study was to assess the primary and secondary resistance of H. pylori strains cultured from adult patients of the Małopolska region of Poland, mainly of Kraków and the surrounding areas, to antibacterial agents (amoxicillin, clarithromycin, metronidazole and levofloxacin). In total, 115 H. pylori strains were isolated, of which 90 strains originated from patients who had never been treated for H. pylori infection, while the remaining 25 were isolated from patients in whom eradication of the infection failed after treatment. All tested H. pylori strains were susceptible to amoxicillin. Forty-four percent of strains isolated were resistant to metronidazole. The primary and secondary resistance to this antimicrobial chemotherapeutic reached 37% and 72% (p = 0.002), respectively. In total, 34% of strains were resistant to clarithromycin, and the ratio of strains with secondary resistance was significantly greater than that of the strains with primary resistance (80% vs. 21%, p < 0.001). The double resistance to both metronidazole and clarithromycin was confirmed in 23% of H. pylori strains. Five percent of H. pylori strains were resistant to levofloxacin, while primary and secondary resistance to this drug accounted for 2% and 16% (p = 0.006), respectively. In total, 4% of H. pylori strains were simultaneously resistant to metronidazole, clarithromycin and levofloxacin. Thus, the high resistance to metronidazole and clarithromycin excludes the possibility of using these drugs for treatment of H. pylori infection without earlier antibiogramming. Levofloxacin, as a drug of high efficacy against H. pylori, should be reserved for an "emergency" therapy and used in a limited capacity in order to preserve its potent antimicrobial activity. The Polish Society of Gastroenterology recommends levofloxacin as a third-line therapy.

Numerous risk factors for Helicobacter pylori antibiotic resistance revealed by extended anamnesis: a Bulgarian study

The aim of this study was to assess risk factors for primary Helicobacter pylori antibiotic resistance by an extended anamnesis. In total, 519 H. pylori strains from untreated symptomatic adults who answered a questionnaire were evaluated. Strain susceptibility was assessed by a breakpoint susceptibility test. Primary resistance rates were 29.5 % for metronidazole, 17.9 % for clarithromycin, 7.3 % for metronidazole+clarithromycin, 4.0 % for tetracycline and 10.8 % for ciprofloxacin. On multivariate analysis, younger (≤65 years) age was an independent predictor for metronidazole resistance. To our knowledge, for the first time, being a member of the health-care profession was revealed as a risk factor for H. pylori resistance to metronidazole and both metronidazole and clarithromycin. Respiratory and urinary tract infections were independent predictors of clarithromycin and ciprofloxacin resistance, respectively. The presence of co-infections was an independent risk factor for clarithromycin, metronidazole and ciprofloxacin resistance. Surprisingly, female sex was the only predictor for tetracycline resistance. The antibiotic resistance rates were not associated with disease type, place of residence, birthplace, educational level, non-steroidal anti-inflammatory drug or proton pump inhibitor use, smoking or dietary factors, such as consumption of coffee, yogurt, green tea, raw garlic, raw onion, honey or meat. There was a trend for higher metronidazole resistance in strains from diabetic patients. In conclusion, the extended anamnesis of H. pylori-positive patients should include data on patient age, sex, whether they are in the health-care profession, co-infections and possibly diabetes to improve the choice of empiric therapy. Tailored treatment based on the extended anamnesis is suggested, and susceptibility testing of the strains is recommended for patients at risk for antibiotic resistance, especially to clarithromycin, fluoroquinolones or both metronidazole and clarithromycin.

Evidence-based guidelines from ESPGHAN and NASPGHAN for Helicobacter pylori infection in children

OBJECTIVE

As the clinical implications of Helicobacter pylori infection in children and adolescents continue to evolve, ESPGHAN and NASPGHAN jointly renewed clinical guidelines using a standardized evidence-based approach to develop updated recommendations for children and adolescents in North America and Europe.

METHODS

An international panel of 11 pediatric gastroenterologists, 2 epidemiologists, 1 microbiologist, and 1 pathologist was selected by societies that developed evidence-based guidelines based on the Delphi process with anonymous voting in a final face-to-face meeting. A systematic literature search was performed on 8 databases of relevance including publications from January 2000 to December 2009. After excluding nonrelevant publications, tables of evidence were constructed for different focus areas according to the Oxford classification. Statements and recommendations were formulated in the following areas: whom to test, how to test, whom to treat, and how to treat. Grades of evidence were assigned to each recommendation based on the GRADE system.

RESULTS

A total of 2290 publications were identified, from which 738 were finally reviewed. A total of 21 recommendations were generated, and an algorithm was proposed by the joint committee providing evidence-based guidelines on the diagnostic workup and treatment of children with H pylori infection.

CONCLUSIONS

These clinical practice guidelines represent updated, best-available evidence and are meant for children and adolescents living in Europe and North America, but they may not apply to those living on other continents, particularly in developing countries with a high H pylori infection rate and limited health care resources.

Benefits of Helicobacter pylori cagE genotyping in addition to cagA genotyping: a Bulgarian study

Associations of Helicobacter pylori cagE status with complex patient characteristics remain to be elucidated in Eastern Europe. The aim of this study was to assess the frequencies of cagE gene and cagA/cagE combinations in H. pylori strains from symptomatic Bulgarian patients and to improve cagA detection. cagA and cagE genotypes were evaluated in 219 patients with single-strain infections. In total, 84.9% of strains were cagA (+), while 68.5% were cagE (+). cagA (+), cagE (+), and cagA (+)/cagE (+) strains were more prevalent in peptic ulcer (93.8%, 84.4%, and 84.4%) compared with nonulcer patients (81.3%, 61.9%, and 61.3%, respectively). In elderly patients, cagE (+) and cagA (+)/cagE (+) strains were 1.9-fold more common than in the 12 children evaluated. Only 10% of the elderly subjects harbored low-virulence cagA (+)/cagE (-) strains compared with 16.8% of adults and 41.7% of children. Intriguingly, prevalence of the cagA (+)/cagE (-) genotype was 2.1-fold lower in men than in women, suggesting a higher frequency of more virulent strains in men. The presence of both cag genes and combinations was not linked to strain susceptibility to clarithromycin or metronidazole, place of residence, or prior therapy. Use of an extra primer pair increased cagA detection in 14.7% of 31 cagA (-) strains. In conclusion, use of a second primer pair for the cagA gene can be recommended in countries with common cagA (+) strains. Although both cag genes were linked to severe diseases in Bulgarian patients, the best discrimination of virulent strains was obtained by the cagA/cagE combination or by the cagE gene alone. cagE prevalence increased gradually with patient age, while the cagA (+)/cagE (-) genotype, implying a disrupted cag pathogenicity island, was associated with both younger age and female gender.

Role of ABC transporter genes msbA and spab in multidrug resistance of Helicobacter pylori

AIM: To evaluate the potential role of ATP-binding cassette (ABC) transporter genes msbA and spab in multidrug resistance (MDR) of Helicobacter pylori (H.pylori).

METHODS: H.pylori strains were isolated from patients with peptic ulcer or gastritis. The minimal inhibitory concentrations (MICs) of ampicillin, ceftriaxone, tetracycline, clarithromycin, ofloxacin and furazolidone for H.pylori strains were determined by agar dilution test. Five sensitive H.pylori strains (four is H.pylori olates and one standard strain NCTC11637) were used to induce multidrug resistance with chloramphenicol. The mRNA expression of msbA and spab in these multidrug-resistant strains was determined by RT-PCR. Two H.pylori gene knockout mutants (MZ1006ΔmsbA and MZ1006Δspab) were constructed by inserting the kanamycin resistance cassette from the pEGFP-N2 vector into the msbA and spab genes, and their susceptibility profiles to nine antibiotics were estimated.

RESULTS: The expression levels of ABC transporter genes msbA and spab in multidrug-resistant H.pylori strains were higher than those in sensitive strains (1.8200 ± 0.5310 vs 0.8420 ± 0.0789, P = 0.018, for msbA; 1.8340 ± 0.2726 vs 1.2180 ± 0.0743, P = 0.015, for spab). MZ1006ΔmsbA and H.pylori MZ1006spab mutants were constructed successfully, and their sensitivity to four of nine antibiotics was significantly enhanced compared to their parental wild-type strains. Both the msbA and spab genes were detected in all isolated strains.

CONCLUSION: ABC transporter genes msbA and spab play an important role in multidrug resistance of H.pylori.

New effective treatment regimen for children infected with a double-resistant Helicobacter pylori strain

BACKGROUND

The increasing number of pediatric patients infected with multiresistant Helicobacter pylori strains calls for evaluation of treatment regimens. Second-line antibiotics such as tetracycline or quinolones are not licensed for children. Because in vivo resistance to metronidazole may be overcome in vivo by a high dose and prolonged intake, we evaluated the eradication rate and side effects of a high-dose triple therapy in pediatric patients with culture-proven double resistance.

PATIENTS AND METHODS

In this open multicentre trial, 62 children (<18 years, body weight >15 kg) infected with an H pylori strain resistant to metronidazole and clarithromycin were treated according to body weight classes with amoxicillin (∼ 75 mg/kg/day), metronidazole (∼ 25 mg/kg/day) and esomeprazole (∼ 1.5 mg/kg/day) for 2 weeks. Adherence and adverse events were assessed by a 2-week diary and telephone interviews at days 7 and 14 of treatment. Primary outcome was a negative C-urea breath test after 6 weeks.

RESULTS

Of 62 patients, 5 were lost to follow-up, 12 were nonadherent, and 45 treated per protocol. Eradication rates were 66% (41/62) [confidence interval 54-78] (intention to treat) and 73% (33/45) [confidence interval 60-86] (per protocol). Success of treatment was not related to dose per kilogram body weight. Mild to moderate adverse events were reported by 21 patients, including nausea (10.8%), diarrhoea (8.9%), vomiting (7.1%), abdominal pain (5.4%), and headache (3.6%), and led to discontinuation in 1 child.

CONCLUSION

High-dose amoxicillin, metronidazole, and esomeprazole for 2 weeks is a good treatment option in children infected with a double resistant H pylori strain.

Multicenter survey of routine determinations of resistance of Helicobacter pylori to antimicrobials over the last 20 years (1990 to 2009) in Belgium

We analyzed the rates of antimicrobial resistance of Helicobacter pylori strains isolated from patients from 1990 to 2009 and identified risk factors associated with resistance. Gastric biopsy specimens were collected from several digestive disease centers in Brussels, Belgium. We routinely performed antimicrobial susceptibility testing for clarithromycin (CLR), metronidazole, amoxicillin, tetracycline, and ciprofloxacin. Evaluable susceptibility testing was obtained for 9,430 strains isolated from patients who were not previously treated for Helicobacter pylori infection (1,527 isolates from children and 7,903 from adults) and 1,371 strains from patients who were previously treated (162 isolates from children and 1,209 from adults). No resistance to amoxicillin was observed, and tetracycline resistance was very rare (<0.01%). Primary metronidazole resistance remained stable over the years, with significantly lower rates for isolates from children (23.4%) than for isolates from adults (30.6%). Ciprofloxacin resistance remained rare in children, while it increased significantly over the last years in adults. Primary clarithromycin resistance increased significantly, reaching peaks in 2000 for children (16.9%) and in 2003 for adults (23.7%). A subsequent decrease of resistance rates down to 10% in both groups corresponded to a parallel decrease in macrolide consumption during the same period. Multivariate logistic regression revealed that female gender, age of the patient of 40 to 64 years, ethnic background, the number of previously unsuccessful eradication attempts, and the different time periods studied were independent risk factors of resistance to clarithromycin, metronidazole, and ciprofloxacin. Our study highlights the need to update local epidemiological data. Thus, the empirical CLR-based triple therapy proposed by the Maastricht III consensus report remains currently applicable to our population.

Two-decade trends in primary Helicobacter pylori resistance to antibiotics in Bulgaria

Evaluating long-term trends in antibiotic resistance can predict earlier the short-term changes in resistance patterns. The aim of the present study was to compare primary resistance rates in 501 Helicobacter pylori strains in 2007 to 2009 to those in 1990 to 1995 (179 strains) and the antibiotic MICs to detect the 20-year resistance evolution. In 2007 to 2009, strains from children exhibited lower resistance rates to metronidazole (16.4%) and ciprofloxacin (2.7%) than those from adults (27.3% and 10.3%, respectively). In 2008 to 2009, more children (29.3%) harbored clarithromycin-resistant strains compared to the adults (17.4%). Overall clarithromycin resistance rate (19.4%) in 2007 to 2009 was much higher than that in 1990 to 1995 (6.2%). MIC(90) of erythromycin in 1990 to 1995 was 142.2-fold lower than that of clarithromycin in 2007 to 2009. Clarithromycin MIC(90) increased >42-fold since 2001 to 2004. Quinolone resistance rate increased 7.7-fold, being 9.2% in 2007 to 2009 versus 1.2% in 1990 to 1995, with a 5-fold increase in MIC(90). Conversely, the amoxicillin resistance decreased from 3.2% in 1996 to 1999 to 0.4% in 2007 to 2009. The MIC(90)'s of tetracycline remained stable but MIC(50)'s of both metronidazole and tetracycline before 1996 decreased about 4-fold to 2007 to 2009. In conclusion, associations between the resistance evolution and patients' age groups as well as the national outpatient antibiotic use have been found. H. pylori resistance to antibiotics showed many long-term changes, with a more rapid evolution for clarithromycin than for the other antibiotics. Metronidazole and tetracycline did not show a resistance evolution but exhibited a decrease in MIC(50) since 1990. The significant increase in ciprofloxacin resistance was found only by extending the study period to 20 years.

The evolution of Helicobacter pylori antibiotics resistance over 10 years in Beijing, China

OBJECTIVES

To evaluate Helicobacter pylori antibiotics resistance evolution from 2000 to 2009 to amoxicillin, clarithromycin, metronidazole, tetracycline, levofloxacin and moxifloxacin in Beijing, China.

METHODS

A total of 374 H. pylori strains isolated from 374 subjects who had undergone upper gastrointestinal endoscopy from 2000 to 2009 were collected and examined by E-test method for antibiotics susceptibility.

RESULTS

The average antibiotics resistance rates were 0.3% (amoxicillin), 37.2% (clarithromycin), 63.9% (metronidazole), 1.2% (tetracycline), 50.3% (levofloxacin) and 61.9% (moxifloxacin). Overall resistance to clarithromycin, metronidazole, and fluoroquinolone increased annually (from 14.8 to 65.4%, 38.9 to 78.8%, and 27.1 to 63.5%, in 2000 or 2006-2007 to 2009, respectively). The secondary resistance rates were much higher than primary rates to these antibiotics, which also increased annually in recent 10 years.

CONCLUSIONS

The trend of clarithromycin, metronidazole, and fluoroquinolone resistance of H. pylori increased over time and the resistance to amoxicillin and tetracycline was infrequent and stable in Beijing. Clarithromycin, metronidazole, and fluoroquinolone should be used with caution for H. pylori eradication treatment.

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%.

Association of iceA and babA genotypes in Helicobacter pylori strains with patient and strain characteristics

Data on the geographic prevalence of Helicobacter pylori iceA and babA alleles in Eastern Europe are still relatively scant. The aim of this study was to evaluate the prevalence of iceA and babA genotypes in Bulgarian symptomatic patients. The iceA and babA genotypes were evaluated by PCR with pure cultures in strains from 196 and 181 patients, respectively. Mixed infections were found in 10.2% of all 196 patients. Prevalence of H. pylori genotypes in patients with single-strain infections was 69.3% for iceA1, 30.7% for iceA2, 82.4% for cagA(+), 89.2% for vacA s1, 10.8% for vacA s2, 39.8% for vacA m1, 60.2% for vacA m2 and 48.8% for babA2. Within the iceA1 positive strains, 94.3% and 88.5% were also vacA s1a and cagA positive, respectively. Of the babA2 positive strains, 100.0%, 92.4% and 72.2% were also vacA s1a, cagA and iceA1 positive, respectively. Ulcer patients had more often strains with cagA positive status and vacA s1a allele. Although neither iceA1 nor babA2 were more common in ulcer patients, the combination of both alleles was more frequent (48.1%) in the ulcer patients than in the rest (28.7%). Clarithromycin susceptible strains had more often iceA1 allele (74.4%) than the resistant strains (55.3%). In conclusion, the results demonstrated a high prevalence of virulent H. pylori in Bulgaria. Both iceA1 and babA2 genotypes were associated with other virulence factors of H. pylori and, in addition, the iceA1 allele was associated with the strain susceptibility.

Influence of efflux pump inhibitors on the multidrug resistance of Helicobacter pylori

AIM: To evaluate the effect of efflux pump inhibitors (EPIs) on multidrug resistance of Helicobacter pylori (H. pylori).

METHODS: H. pylori strains were isolated and cultured on Brucella agar plates with 10% sheep’s blood. The multidrug resistant (MDR) H. pylori were obtained with the inducer chloramphenicol by repeated doubling of the concentration until no colony was seen, then the susceptibilities of the MDR strains and their parents to 9 antibiotics were assessed with agar dilution tests. The present study included periods before and after the advent of the EPIs, carbonyl cyanide m-chlorophenyl hydrazone (CCCP), reserpine and pantoprazole), and the minimum inhibitory concentrations (MICs) were determined accordingly. In the same way, the effects of 5 proton pump inhibitors (PPIs), used in treatment of H. pylori infection, on MICs of antibiotics were evaluated.

RESULTS: Four strains of MDR H. pylori were induced successfully, and the antibiotic susceptibilities of MDR strains were partly restored by CCCP and pantoprazole, but there was little effect of reserpine. Rabeprazole was the most effective of the 5 PPIs which could decrease the MICs of antibiotics for MDR H. pylori significantly.

CONCLUSION: In vitro, some EPIs can strengthen the activities of different antibiotics which are the putative substrates of the efflux pump system in H. pylori.