Pylori Isolates Research Articles

Helicobacter pylori vacA d1/-i1 genotypes and geographic differentiation between high and low incidence areas of gastric cancer in Iran.

Helicobacter pylori (H. pylori)-specific genotypes have been closely correlated with an increased risk of gastric cancer (GC). The present study aimed to determine the distribution of H. pylori pathogenic genotypes amongst Iranians infected with strains representing European ancestry in areas with different GC incidence. A total of 138 H. pylori isolates from ten districts in Iran were used for genotyping. The following genotypic frequency was observed: vacA s1 (94.9%), s2 (5.1%), m1 (24.6%), m2 (75.4%), d1 (39.9%), d2 (60.1%), i1 (40.6%), i2 (59.4%), iceA1 (76.8%), iceA2 (52.9%), iceA1/2 (29.7%), babA2 (40.6%), and cagA (65.9%). Hierarchical analyses of molecular variance (AMOVA) for the vacA d1, d2, i1, and i2 alleles and iceA1 and iceA1/2 genes found significant levels of genetic differentiation among populations (P < 0.05). Prevalence of the vacA d1, i1, and iceA1/2 (but not iceA1) genes and vacA d1/i1, vacA d1/iceA1, vacA d1/iceA1/2, vacA d1/cagA+, vacA i1/iceA1, vacA i1/iceA1/2, and vacA i1/cagA+ genotypes were significantly higher (>2- or 3-fold) among H. pylori isolates from high incidence GC areas that had age-standardized rates (ASRs) of >20/105 (max. 51.8/105) when compared with those from low incidence (ASRs <10/105) GC areas (P < 0.005, for the latter, P = 0.016). In contrast, the vacA d2/i2, m2/d2, and m2/i2 genotypes were significantly more prevalent in low compared to high incidence GC areas (P < 0.005). The results of Mantel's test only showed a low correlation between genetic and geographic distances for the iceA1 and iceA1/2 (but not vacA alleles, iceA2, babA2, and cagA) genes among ten districts of Iran (r = 0.098 and 0.074, respectively, P < 0.05). We propose that the H. pylori vacA d1/-i1 genotypes, which are new determinants of GC, have tremendous potential for differentiating H. pylori strains from high and low incidence GC areas in Iran.

High Helicobacter pylori Resistance to Metronidazole and Clarithromycin in Brazilian Children and Adolescents

The aim of the present study was to assess the primary and secondary resistance of Helicobacter pylori strains to clarithromycin, amoxicillin, furazolidone, tetracycline, and metronidazole, the conventional antibiotics presently used in Brazilian children and adolescents. Seventy-seven consecutive H pylori strains, 71 of 77 strains obtained from patients without previous eradication treatment for H pylori infection, and 6 strains from patients in whom previous eradication treatment had failed. Global rate of resistance was 49.3% (38/77): 40% of strains were resistant to metronidazole, 19.5% to clarithromycin, and 10.4% to amoxicillin. All of the tested H pylori strains were susceptible to furazolidone and tetracycline. Multiple resistance were detected in 18.2% (14/77 patients) of the strains: 6 of 14 (43%) simultaneously resistant to clarithromycin and metronidazole; 5 of 14 (36%) to amoxicillin and metronidazole; 2 of 14 (14%) to amoxicillin, clarithromycin, and metronidazole; and 1 of 14 (7%) to clarithromycin and amoxicillin. The high resistance rate to metronidazole and clarithromycin observed in clinical H pylori isolates can exclude these antimicrobials in empirical eradication treatment in Brazil. Otherwise, furazolidone and tetracycline presented no resistance. Properly assessing the risks and benefits, these 2 antimicrobials and their derivatives could be used in empirical eradication schedules, both associated with amoxicillin, which showed a low resistance rate despite its wide use in pediatric patients.

Amino acid polymorphisms flanking the EPIYA‐A motif of Helicobacter pylori CagA C‐terminal region is associated with gastric cancer in East China: Experience from a single center

The study aimed to investigate the relationship between gastroduodenal disease and the diversity of the cagA 3' variable region and the amino acid polymorphisms in the Glu-Pro-Ile-Tyr-Ala (EPIYA) segments of the CagA C-terminal region of Helicobacter pylori (H. pylori). Gastric mucosal specimens from 170 patients in our center (Nanjing, Jiangsu Province, China) were collected and the genomic DNA of the H. pylori strains was extracted directly from biopsied specimens. Polymerase chain reaction (PCR) was used to amplify the cagA gene, and diversity in its 3' variable region was assessed by direct sequencing. A total of 154 (90.6%) H. pylori isolates were cagA-positive, but the presence of this gene alone was not associated with the type of gastroduodenal disease. A total of 151 (88.8%) strains had the East Asian type EPIYA-D sequence, most of which were of ABD subtype. Three isolates from patients with chronic gastritis possessed the EPIYA-C segment. The sequences flanking the EPIYA motifs contained polymorphisms at seven residues, among which amino acid positions 878 and 879 had a statistically significant association with gastric cancer (P = 0.021). Amino acid change from glycine to aspartic acid at residue 968 was present only in patients with gastric cancer (4/20) (P < 0.001). Most H. pylori strains present in our study are of the CagA-ABD subtype. Polymorphisms at amino acids 878 and 879 flanking the EPIYA-A motif are statistically associated with gastric cancer.

Genome sequences of 65 Helicobacter pylori strains isolated from asymptomatic individuals and patients with gastric cancer, peptic ulcer disease, or gastritis.

Helicobacter pylori, inhabitant of the gastric mucosa of over half of the world population, with decreasing prevalence in the U.S., has been associated with a variety of gastric pathologies. However, the majority of H. pylori-infected individuals remain asymptomatic, and negative correlations between H. pylori and allergic diseases have been reported. Comprehensive genome characterization of H. pylori populations from different human host backgrounds including healthy individuals provides the exciting potential to generate new insights into the open question whether human health outcome is associated with specific H. pylori genotypes or dependent on other environmental factors. We report the genome sequences of 65 H. pylori isolates from individuals with gastric cancer, preneoplastic lesions, peptic ulcer disease, gastritis, and from asymptomatic adults. Isolates were collected from multiple locations in North America (USA and Canada) as well as from Columbia and Japan. The availability of these H. pylori genome sequences from individuals with distinct clinical presentations provides the research community with a resource for detailed investigations into genetic elements that correlate either positively or negatively with the epidemiology, human host adaptation, and gastric pathogenesis and will aid in the characterization of strains that may favor the development of specific pathology, including gastric cancer.

Antibiotic Susceptibility of Helicobacter pylori Clinical Isolates in Hamadan, West of Iran

Background: Surveillance data on Helicobacter pylori antibiotic susceptibilities are limited in Hamadan, Iran. Since antibiotic resistance is one of the reasons in therapies failure. Objectives: Thus the resistance patterns of H. pylori strains to the antibiotics metronidazole, clarithromycin, amoxicillin and tetracycline were evaluated. Patients and Methods: Gastric biopsy specimens of 153 patients with nonulcer dyspepsia, peptic ulcer dyspepsia, and peptic cancer collected during May 2010 to February of 2011, and were cultured on Brucella agar (Merck, Germany) under microaerophilic conditions. H. pylori isolates were identified using standard biochemical test. Eighty three (54.2 %) specimens had positive results by culture. Antimicrobial susceptibility testing was performed by disc diffusion method. Results: Totally in vitro resistance rates were 63.8% for metronidazole, 26.5% for clarithromycin, and 7.2% for amoxicillin. Although, 25.3% of strains showed resistance to two antibiotics, and 3.6% to three antibiotics. Tetracycline resistance was identified in only two isolates. Fifty nine percent of the clarithromycin resistant strains also showed resistance to metronidazole. No gender and age associations with resistance were detected. Conclusion: Our results showed a high incidence of metronidazole resistance (often combined with clarithromycin-resistance) in the isolates. Continuous surveillance is recommended to examine the treatment strategies for H. pylori eradication.

Usefulness of antimicrobial susceptibility in the eradication of Helicobacter pylori

The rate of eradication of Helicobacter pylori with standard triple therapy using omeprazole, amoxicillin and clarithromycin (OAC) is unacceptable in populations with high rates of clarithromycin resistance (15–20%). The aim of this study was to compare the efficacy of 10-day OAC therapy as the first-line treatment in patients diagnosed by culture with antimicrobial susceptibility or diagnosed by a 13C-labelled urea breath test (UBT) without antimicrobial susceptibility in an area where the clarithromycin resistance rate was 15–20%. This was a retrospective cohort study of 266 patients, recruited consecutively throughout 2008. A total of 247 H. pylori-infected patients received antibiotic therapy (221 received the 10-day OAC therapy and 26 received other regimens) of which 134 patients were diagnosed by culture of gastric samples followed by antimicrobial susceptibility testing and 113 were diagnosed by UBT. In all patients, the eradication of H. pylori was checked by UBT. The cost of eradication by 10-day OAC treatment was assessed in each patient. The success rate of 10-day OAC therapy in patients diagnosed by culture and by UBT was 88% (103/117) and 49% (51/104), respectively (p <0.0005). The treatment was also more cost-effective in the former of these two groups (€571 versus €666). To perform culture and antimicrobial susceptibility of the H. pylori isolates was a more successful and cost effective strategy than empirical 10-day OAC treatment in populations with high rates of resistance to clarithromycin.

Characterization of Helicobacter pylori bacteriophage KHP30.

Helicobacter pylori inhabits the stomach mucosa and is a causative agent of stomach ulcer and cancer. In general, bacteriophages (phages) are strongly associated with bacterial evolution, including the development of pathogenicity. Several tailed phages have so far been reported in H. pylori. We have isolated an H. pylori phage, KHP30, and reported its genomic sequence. In this study, we examined the biological characteristics of phage KHP30. Phage KHP30 was found to be a spherical lipid-containing phage with a diameter of ca. 69 nm. Interestingly, it was stable from pH 2.5 to pH 10, suggesting that it is adapted to the highly acidic environment of the human stomach. Phage KHP30 multiplied on 63.6% of clinical H. pylori isolates. The latent period was ca. 140 min, shorter than the doubling time of H. pylori (ca. 180 min). The burst size was ca. 13, which was smaller than the burst sizes of other known tailed or spherical phages. Phage KHP30 seemed to be maintained as an episome in H. pylori strain NY43 cells, despite a predicted integrase gene in the KHP30 genomic sequence. Seven possible virion proteins of phage KHP30 were analyzed using N-terminal protein sequencing and mass spectrometry, and their genes were found to be located on its genomic DNA. The genomic organization of phage KHP30 differed from the genomic organizations in the known spherical phage families Corticoviridae and Tectiviridae. This evidence suggests that phage KHP30 is a new type of spherical phage that cannot be classified in any existing virus category.

Diversity of Helicobacter Pylori cagA and vacA Genes and Its Relationship with Clinical Outcomes in Azerbaijan, Iran.

The purpose of this research was to analyze cagA and vacA genotypes status in H. pylori isolates and relationship with clinical outcomes. Gastric biopsy specimens were cultured for H. pylori isolation and cagA and vacA genes were detected in these isolates. Data were collected and the results were analyzed using χ2 and Fishers exact tests by SPSS software version. 16. Of the total 115 H. pylori isolates, 79 (68.7 %) were cagA positive and 82 (71.3%) of isolates contained the s1 allele which 33 (28.7%) were subtype s2. s1m2 was the most frequent vacA allelic combination in the H. pylori isolates examined (63 cases), followed by s2m2 (31 cases), s1m1 (19 cases) and s2m1 (2 case). Strains cagA positive were more frequent in peptic ulcer diseases patients than non ulcer diseases patients, as 47 (59.5%) and 32 (40.5%), while cagA negative were low, as 15 (41.7%) and 21 (58.3%), respectively. We found that the cagA and vacA status were not related to clinical outcomes in this area. Overall, in the present study, vacA s1/m2, cagA-positive strains were predominant irrespective of clinical outcome, but s2/m1 was rare.

Ethnicity association ofHelicobacter pylorivirulence genotype and metronidazole susceptibility

To characterise the cag pathogenicity island in Helicobacter pylori (H. pylori) isolates by analysing the strains' vacA alleles and metronidazole susceptibilities in light of patient ethnicity and clinical outcome. Ninety-five H. pylori clinical isolates obtained from patients with dyspepsia living in Malaysia were analysed in this study. Six genes in the cagPAI region (cagE, cagM, cagT, cag13, cag10 and cag67) and vacA alleles of the H. pylori isolates were identified by polymerase chain reaction. The isolates' metronidazole susceptibility was also determined using the E-test method, and the resistant gene was characterised by sequencing. More than 90% of the tested isolates had at least one gene in the cagPAI region, and cag67 was predominantly detected in the strains isolated from the Chinese patients, compared with the Malay and Indian patients (P < 0.0001). The majority of the isolates (88%) exhibited partial deletion (rearrangement) in the cagPAI region, with nineteen different patterns observed. Strains with intact or deleted cagPAI regions were detected in 3.2% and 8.4% of isolates, respectively. The prevalence of vacA s1m1 was significantly higher in the Malay and Indian isolates, whereas the isolates from the Chinese patients were predominantly genotyped as vacA s1m2 (P = 0.018). Additionally, the isolates from the Chinese patients were more sensitive to metronidazole than the isolates from the Malay and Indian patients (P = 0.047). Although we attempted to relate the cagPAI genotypes, vacA alleles and metronidazole susceptibilities to disease outcome, no association was observed. The vacA alleles were distributed evenly among the strains with intact, partially deleted or deleted cagPAI regions. Interestingly, the strains exhibiting an intact cagPAI region were sensitive to metronidazole, whereas the strains with a deleted cagPAI were more resistant. Successful colonisation by different H. pylori genotypes is dependent on the host's genetic makeup and may play an important role in the clinical outcome.

Anti-Helicobacter pylori activity and Structure-Activity Relationship study of 2-Alkylthio-5-(nitroaryl)-1,3,4-thiadiazole Derivatives.

Nitro-containing heteroaromatic derivatives structurally related to nitroimidazole (Metronidazole) are being extensively evaluated against Helicobacter pylori isolates. On the other hand, 1,3,4-thiadiazole derivatives have also demonstrated promising antibacterial potential. In present study, we evaluated anti-H. pylori activity of novel hybrid molecules bearing nitroaryl and 1,3,4-thiadiazole moieties. Anti-H. pylori activity of novel 5-(5-nitroaryl)-1,3,4-thiadiazole derivatives bearing different bulky alkylthio side chains at C-2 position of thiadiazole ring, were assessed against three different metronidazole resistant H. pylori isolates by paper disk diffusion method. Most of the compounds demonstrated moderate to strong inhibitory response especially at 25 μg/disk. The structure-activity relationship study of the compounds demonstrated that introduction of different alkylthio moieties at C-2 position of thiadiazole ring; alter the inhibitory activity which is mainly dependent on the type of C-5 attached nitrohetercyclic ring. The promising compound of this scaffold, bearing 1-methyl-5-nitroimidazole moiety at C-5 and α-methylbenzylthio side chain at C-2 position of thiadiazole ring, showed strong inhibitory response against metronidazole resistant H. pylori isolates at 12.5 μg/disk (the inhibition zone diameter at all evaluated concentrations (12.5- 100 μg/disk) is >50 mm). Novel 5-(5-nitroaryl)-1,3,4-thiadiazole scaffold bearing different C-2 attached thio-pendant moieties with promising anti-H. pylori potential were identified. Among different nitroheterocycles, 5-nitrofuran and 5-nitroimidazole moieties were preferable for the substitution at C-5 position of 1,3,4-thiadiazole ring. Introduction of different alkylthio side chains at C-2 position of central ring alter the inhibitory activity which is mainly dependent on the type of C-5 attached nitrohetercyclic ring.

Phylogenetic analysis of Helicobacter pylori cagA gene of Turkish isolates and the association with gastric pathology

BackgroundThe cagA gene is one of the important virulence factors of Helicobacter pylori. The diversity of cagA 5′ conserved region is thought to reflect the phylogenetic relationships between different H. pylori isolates and their association with peptic ulceration. Significant geographical differences among isolates have been reported. The aim of this study is to compare Turkish H. pylori isolates with isolates from different geographical locations and to correlate the association with peptic ulceration.MethodsTotal of 52 isolates of which 19 were Turkish and 33 from other geographic locations were studied. Gastric antral biopsies collected from 19 Turkish patients (Gastritis = 12, ulcer = 7) were used to amplify the cagA 5′ region by PCR then followed by DNA sequencing.ResultsThe phylogenetic tree displayed 3 groups: A) a mix of 2 sub-groups “Asian” and “African/Anatolian/Asian/European”, B) “Anatolian/European” and C) “American-Indian”. Turkish H. pylori isolates clustered in the mixed sub-group A were mostly from gastritis patients while those clustered in group B were from peptic ulcer patients. A phylogenetic tree constructed for our Turkish isolates detected distinctive features among those from gastritis and ulcer patients. We have found that 2/3 of the gastritis isolates were clustered alone while 1/3 was clustered together with the ulcer isolates. Several amino acids were found to be shared between the later groups but not with the first group of gastritis.ConclusionsThis study provided an additional insight into the profile of our cagA gene which implies a relationship in geographic locations of the isolates.

Prevalence of Antibiotic Resistance and Minimum Inhibitory Concentrations of Helicobacter pylori Isolates from Clinical Gastritis Patients, Saudi Arabia

Background: Establishing effective and acceptable treatment regimens for patients infected with Helicobacter pylori continues to pose problems for physician and patient alike in Saudi Arabia. The aim of the study was to assess the antibiotics resistance and to find out the MICs of the drugs which are commonly used against H. Pylori. Methods: A total of one hundred antral biopsy specimens were collected and processed from which seventy-six strains of H. pylori were isolated. All the isolates were performed antibiotics sensitivity and E-test. Results: The antibiotics result revealed that of H. pylori isolates 72% strains were resistant to metronidazole and 8% of isolates were resistant to clarithromycin. On the basis of antibiotics resistant a five different antibiotics phenotypes were found among H. pylori isolates. The distribution of metronidazole MICs was high in the range between 32 to128 mg/L. However all other antibiotics showed the effective MICs range was below 1 mg/L. Conclusions: Our findings suggested that resistance to metronidazole has been increasing in the Saudi population. The resistance may be linked to the frequentuse of these antimicrobial agents for treating parasitic infections. The E test results revealed that the most effective antibiotic MICs were amoxicillin and clarithromycin against H. Pylori infection. Keywords: Peptic ulcer, Helicobacter pylori, Antral biopsy, Antibiotics, Resistance. Read more →

Diversity of Helicobacter pylori genotypes in Iranian patients with different gastroduodenal disorders.

To investigate the diversity of Helicobacter pylori (H. pylori) genotypes and correlations with disease outcomes in an Iranian population with different gastroduodenal disorders. Isolates of H. pylori from patients with different gastroduodenal disorders were analyzed after culture and identification by phenotypic and genotypic methods. Genomic DNA was extracted with the QIAamp DNA mini kit (Qiagen, Germany). After DNA extraction, genotyping was done for cagA, vacA (s and m regions), iceA (iceA1 , iceA2 ) and babA with specific primers for each allele using polymerase chain reaction (PCR). All patients' pathologic and clinical data and their relation with known genotypes were analyzed by using SPSS version 19.0 software. χ² test and Fisher's exact test were used to assess relationships between categorical variables. The level of statistical significance was set at P < 0.05. A total of 71 isolates from 177 patients with different gastroduodenal disorders were obtained. Based on analysis of the cagA gene (positive or negative), vacA s-region (s1 or s2), vacA m-region (m1 or m2), iceA allelic type (iceA1 and iceA2 ) and babA gene (positive or negative), twenty different genotypic combinations were recognized. The prevalence of cagA, vacA s1 , vacA s2 , vacA m1 , vacA m2 , iceA1 , iceA2 , iceA1+iceA2 and babA were 62%, 78.9%, 19.7%, 21.1%, 78.9%, 15.5%, 22.5%, 40.8% and 95.8%, respectively. Interestingly, evaluation of PCR results for cagA in 6 patients showed simultaneous existence of cagA variants according to their size diversities that proposed mixed infection in these patients. The most prevalent genotype in cagA-positive isolates was cagA⁺/vacAs1m2 /iceA1 +A2 /babA+ and in cagA-negative isolates was cagA⁻/vacAs1m2 /iceA-/babA+. There were no relationships between the studied genes and histopathological findings (H. pylori density, neutrophil activity, lymphoid aggregation in lamina propria and glandular atrophy). The strains which carry cagA, vacAs1/m1 , iceA2 and babA genes showed significant associations with severe active chronic gastritis (P = 0.011, 0.025, 0.020 and 0.031, respectively). The vacAs1 genotype had significant correlation with the presence of the cagA gene (P = 0.013). Also, babA genotype showed associations with cagA (P = 0.024). In the combined genotypes, only cagA⁺/vacAs1m1 /iceA2 /babA+ genotype showed correlation with severe active chronic gastritis (P = 0.025). This genotyping panel can be a useful tool for detection of virulent H. pylori isolates and can provide valuable guidance for prediction of the clinical outcomes.

In vitroeffect of amoxicillin and clarithromycin on the 3’ region ofcagAgene inHelicobacter pyloriisolates

To evaluate the in vitro effect of amoxicillin and clarithromycin on the cag pathogenicity island (cag PAI). One hundred and forty-nine clinical isolates of Helicobacter pylori (H. pylori) cultured from gastric biopsies from 206 Colombian patients with dyspeptic symptoms from a high-risk area for gastric cancer were included as study material. Antimicrobial susceptibility was determined by the agar dilution method. Resistant isolates at baseline and in amoxicillin and clarithromycin serial dilutions were subjected to genotyping (cagA, vacA alleles s and m), Glu-Pro-Ile-Tyr-Ala (EPIYA) polymerase chain reaction and random amplified polymorphic DNA (RAPD). Images of the RAPD amplicons were analyzed by Gel-Pro Analyzer 4.5 program. Cluster analyses was done using SPSS 15.0 statistical package, where each of the fingerprint bands were denoted as variables. Dendrograms were designed by following Ward's clustering method and the estimation of distances between each pair of H. pylori isolates was calculated with the squared Euclidean distance. Resistance rates were 4% for amoxicillin and 2.7% for clarithromycin with 2% double resistances. Genotyping evidenced a high prevalence of the genotype cagA-positive/vacA s1m1. The 3' region of cagA gene was successfully amplified in 92.3% (12/13) of the baseline resistant isolates and in 60% (36/60) of the resistant isolates growing in antibiotic dilutions. Upon observing the distribution of the number of EPIYA repetitions in each dilution with respect to baseline isolates, it was found that in 61.5% (8/13) of the baseline isolates, a change in the number of EPIYA repetitions lowered antibiotic pressure. The gain and loss of EPIYA motifs resulted in a diversity of H. pylori subclones after bacterial adjustment to changing conditions product of antibiotic pressure. RAPD PCR evidenced the close clonal relationship between baseline isolates and isolates growing in antibiotic dilutions. Antibiotic pressure does not induce loss of the cag pathogenicity island, but it can lead--in most cases--to genetic rearrangements within the 3' region cagA of the founding bacteria that can affect the level of tyrosine phosphorylation impacting on its cellular effects and lead to divergence of cagA-positive subclones.

Antibacterial Activities of Refined Deep Seawater on Helicobacter pylori

Helicobacter pylori (H. pylori) is believed to infect about half of the world’s population and is related to many gastric diseases, duodenal ulcer and a variety of non-gastrointestinal tract disorders. In this study, the inhibitory effects of refined deep seawater (RDSW) on H. pylori growth and motility were investigated. Deep seawater was collected offshore from Muroto, Kochi, Japan, desalinated, and refined to increase the mineral concentration. The in vitro assays with 16 H. pylori isolates by 20 types of RDSW with combinations of 5 Mg/Ca ratios and 4 degrees of hardness were performed. Bacterial growth and mobility were inhibited in a hardness-dependent manner. A difference in the Mg/Ca ratio influenced the inhibitory effects when the degree of hardness was unchanged. At a hardness of 1000, anti-H. pylori activities were observed in all strains for at least at one of the 5 Mg/Ca ratios. Evaluation of the anti-H. pylori effects was then conducted in vivo in Mongolian gerbils, to which RDSW at 5 different Mg/Ca ratios (hardness: 1000) was administered for 2 weeks. The number of H. pylori colonized in the stomach showed a significant decrease with 2 types of RDSW (C and D), compared with commercial mineral water. Furthermore, 1 L of each 5 types of RDSW was given daily for 10 days to healthy subjects infected with H. pylori. An urea breath test examined before and after the 10-day period showed reduction of Δ13C values in more of these subjects compared to controls who drank commercial mineral water. In vivo anti-H. pylori effects were observed in ≥90% of subjects drinking any of the 5 types of RDSW. These results raised the possibility that the application of refined deep seawater can be available for prevention of or as an adjuvant therapy for H. pylori infection.

Comparative in vitro antimicrobial susceptibility and synergistic activity of antimicrobial combinations against Helicobacter pylori isolates in Taiwan

Antimicrobial resistance is a major determinant of Helicobacter pylori treatment failures. We conducted a population-based survey to monitor changing antimicrobial susceptibility of H. pylori isolates in Taiwan, with a focus on combinatorial effects of synergism and the influence of acidity. H. pylori isolates from endoscopic specimens taken from patients enrolled at two medical centers were obtained between January 2008 and December 2009. Minimum inhibitory concentrations (MICs) were determined by agar dilution and Etest methods. Agar media of varying pH (pH 7.3, 6.0, or 5.0) were used to assess whether acidity influences the bactericidal effects of the agents tested. Time-kill assays were used to assess for synergism between different drug combinations. A total of 176 non-duplicate H. pylori isolates from endoscopic specimens were tested. The following MIC90 (mg/L) (susceptible) results were obtained at neutral pH 7.3: amoxicillin, 0.25 (100%); tetracycline, 0.5 (100%); metronidazole, 32 (67.6%); clarithromycin, 0.25 (90.3%); ciprofloxacin, 1 (92.0%); gemifloxacin, 0.5 (94.9%); levofloxacin, 1 (93.2%); and moxifloxacin, 1 (91.5%). A decrease in pH from 6.0 to 5.0 significantly decreased the antimicrobial activity of levofloxacin and moxifloxacin against H. pylori. For clarithromycin-susceptible isolates, levofloxacin combined with clarithromycin provided both synergistic and bactericidal effects. For clarithromycin-resistant isolates with amoxicillin hypersusceptibility (MIC <0.01 mg/L), levofloxacin with amoxicillin or minocycline had at best additive effect but no bactericidal effects. Amoxicillin, tetracycline, clarithromycin, and fluoroquinolones, but not metronidazole, showed good in vitro anti-H. pylori activity (>90% susceptible). Synergism was only observed for clarithromycin-susceptible isolates. Acidity adversely influenced the antimicrobial activity of levofloxacin against H. pylori.

Helicobacter pylori: Detection of iceA1 and iceA2 Genes in the Same Strain in Mexican Isolates

Helicobacter pylori iceA1 and iceA2 gene amplification is usually performed to identify mixed populations as both genes are apparently reportedly exclusive. However, some strains isolated from Mexico show both iceA genes. The aim of this study was to establish the frequency of these genes in Mexican isolates and genomic diversity of the H. pylori strains. One hundred thirty six biopsies were obtained from 68 patients (39 children and 29 adults). The presence of H. pylori was confirmed in 3/18 children and 6/19 adults by culture. There were 93 clinical strains isolated from nine patients. Additionally, we studied 37 strains from a strain collection isolated from 10 patients. The strains were genotyped and dual iceA genes were identified by polymerase chain reaction (PCR) and amplicons were sequenced. In addition, an enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) assay was performed as fingerprinting method. The genotypification of the H. pylori isolates indicated that all strains were vacA+; 86% babA2+, 86% cagA+, 82% vacA s1m1+, 19% iceA1+, 9% iceA2+, and 72% of them carried both iceA1 and iceA2 genes. The ERIC-PCR profiling revealed that the strains clustered in eight genetic groups depending on the presence of iceA1, iceA2 or both. A basic local multiple alignment analysis of the nucleotide sequences revealed that the iceA1 and iceA2 genes exhibited no relevant similarity. The results here showed the presence of triple-positive strains (babA, cagA, vacA) of H. pylori and strains carrying simultaneously both iceA1 and iceA2 genes.

Time trends of primary antibiotic resistance of Helicobacter pylori isolates in Southern Croatia

Time trends of primary antibiotic resistance of Helicobacter pylori isolates in Southern Croatia

Polymerase chain reaction-restriction fragment length polymorphism analysis of Helicobacter pylori isolates from patients with gastrointestinal complaints in Eastern Turkey

The aim of this study was to investigate the genetic variations among isolates ofHelicobacter pylori (H. pylori) obtained from patients with gastritis (G) and peptic ulcer (PU) in Elazig Province, East of Turkey and to determine association between restriction fragment length polymorphism (RFLP) types and clinical/histopathological outcomes. Determining the dominant genotypes among H. pylori isolates would detect potential risk and aid in the development of improved treatment and control strategies. Sixty one H. pylori-isolates [29 males and 32 females, 51 with G, 10 with PU (duodenal ulcer (DU) or gastric ulcer (GU)] were examined by polymerase chain reaction-restriction fragment length polymorphism analysis (PCR-RFLP) for detecting the genetic diversity among H. pyloriisolates. By (PCR-RFLP) analysis, H. pylori isolates yielded five (A-E) different band profiles. The most common type of H. pylori isolates from patients with chronic active, chronic active non-atrophic and chronic atrophic G was type B (55, 88.9 and 100%, respectively). However, most of the isolates from patients with DU and GU were type D (75 and 100%, respectively). To the best of our knowledge, this is the first report on PCR-RFLP analysis of H. pylori isolates in Elazig Province, the East of Turkey. This study indicated that the genetic heterogenecity among H. pylori isolated from patients is low, and the clinical/histopathological outcomes of H. pylori isolates associated to the RFLP types. Key words: Helicobacter pylori, patients, genetic variation, polymerase chain reaction-restriction fragment length polymorphism.

High clarithromycin and levofloxacin resistance in Helicobacter Pylori strains isolated from patients in our high-volume academic endoscopic centre

Background: The antibiotic susceptibility is the cornerstone for the eradication strategies of Helicobacter pylori (H. pylori).