Vacuolating toxin gene polymorphism among Helicobacter pylori clinical isolates and its association with m1, m2, or chimeric vacA middle types

Prevalence of vacA, cagA and babA2 genes in Cuban Helicobacter pylori isolates

AIM

To investigate the prevalence of vacuolating cytotoxin (vacA), cytotoxin associated gene A (cagA) and blood adhesion binding antigen (babA2) genotypes of Helicobacter pylori (H pylori) isolates from Cuban dyspeptic patients.

METHODS

DNA was extracted from H pylori-positive cultures taken from 130 dyspeptic patients. Genotyping was performed by PCR, using specific primers for vacA (s1, s2, m1, m2), cagA and babA2 genes. Endoscopic observations and histological examinations were used to determine patient pathologies.

RESULTS

vacA alleles s1, s2, m1 and m2 were detected in 96 (73.8%), 34 (26.2%), 75 (57.7%) and 52 isolates (40%), respectively, while the cagA gene was detected in 95 isolates (73.2%). One hundred and seven isolates (82.3%) were babA2-positive. A significant correlation was observed between vacAs1m1 and cagA and between vacAs1m1 and babA2 genotypes (P < 0.001 and P < 0.05, respectively) and between babA2 genotype and cagA status (P < 0.05); but, no correlation was observed between vacAs1 and babA2 genotypes. Eighty five (65.4%) and 73 (56.2%) strains were type 1 (vacAs1-cagA-positive) and "triple-positive" (vacAs1-cagA-babA2-positive), respectively, and their presence was significantly associated with duodenal ulcer (P < 0.01 and P < 0.001, respectively).

CONCLUSION

The distribution of the main virulence factors in the Cuban strains in this study resembled that of the Western-type strains, and the more virulent H pylori isolates were significantly associated with duodenal ulcer, ulcer disease being the worst pathology observed in the group studied.

Prevalence of vacA, cagA and babA2 genes in Cuban Helicobacter pylori isolates

AIM

To investigate the prevalence of vacuolating cytotoxin (vacA), cytotoxin associated gene A (cagA) and blood adhesion binding antigen (babA2) genotypes of Helicobacter pylori (H pylori) isolates from Cuban dyspeptic patients.

METHODS

DNA was extracted from H pylori-positive cultures taken from 130 dyspeptic patients. Genotyping was performed by PCR, using specific primers for vacA (s1, s2, m1, m2), cagA and babA2 genes. Endoscopic observations and histological examinations were used to determine patient pathologies.

RESULTS

vacA alleles s1, s2, m1 and m2 were detected in 96 (73.8%), 34 (26.2%), 75 (57.7%) and 52 isolates (40%), respectively, while the cagA gene was detected in 95 isolates (73.2%). One hundred and seven isolates (82.3%) were babA2-positive. A significant correlation was observed between vacAs1m1 and cagA and between vacAs1m1 and babA2 genotypes (P < 0.001 and P < 0.05, respectively) and between babA2 genotype and cagA status (P < 0.05); but, no correlation was observed between vacAs1 and babA2 genotypes. Eighty five (65.4%) and 73 (56.2%) strains were type 1 (vacAs1-cagA-positive) and "triple-positive" (vacAs1-cagA-babA2-positive), respectively, and their presence was significantly associated with duodenal ulcer (P < 0.01 and P < 0.001, respectively).

CONCLUSION

The distribution of the main virulence factors in the Cuban strains in this study resembled that of the Western-type strains, and the more virulent H pylori isolates were significantly associated with duodenal ulcer, ulcer disease being the worst pathology observed in the group studied.

Prevalence of vacA, cagA and babA2 genes in Cuban Helicobacter pylori isolates

AIM: To investigate the prevalence of vacuolating cytotoxin (vacA), cytotoxin associated gene A (cagA) and blood adhesion binding antigen (babA2) genotypes of Helicobacter pylori (H pylori) isolates from Cuban dyspeptic patients.

METHODS: DNA was extracted from H pylori-positive cultures taken from 130 dyspeptic patients. Genotyping was performed by PCR, using specific primers for vacA (s1, s2, m1, m2), cagA and babA2 genes. Endoscopic observations and histological examinations were used to determine patient pathologies.

RESULTS: vacA alleles s1, s2, m1 and m2 were detected in 96 (73.8%), 34 (26.2%), 75 (57.7%) and 52 isolates (40%), respectively, while the cagA gene was detected in 95 isolates (73.2%). One hundred and seven isolates (82.3%) were babA2-positive. A significant correlation was observed between vacAs1m1 and cagA and between vacAs1m1 and babA2 genotypes (P < 0.001 and P < 0.05, respectively) and between babA2 genotype and cagA status (P < 0.05); but, no correlation was observed between vacAs1 and babA2 genotypes. Eighty five (65.4%) and 73 (56.2%) strains were type 1 (vacAs1-cagA-positive) and “triple-positive” (vacAs1-cagA-babA2-positive), respectively, and their presence was significantly associated with duodenal ulcer (P < 0.01 and P < 0.001, respectively).

CONCLUSION: The distribution of the main virulence factors in the Cuban strains in this study resembled that of the Western-type strains, and the more virulent H pylori isolates were significantly associated with duodenal ulcer, ulcer disease being the worst pathology observed in the group studied.

Association of antibiotic resistance and higher internalization activity in resistant Helicobacter pylori isolates

OBJECTIVES

Helicobacter pylori resistance to antibiotics is the main factor for therapy failure, while other features remain largely unknown. The aims of this study are to investigate the relationship of antibiotic resistance and in vitro internalization activity between cure and failure isolates and to determine whether failures are associated with persistence of the same predominant strain.

METHODS

Fifty-three isolates from forty-seven patients (cure group, n = 31; failure group, n = 16) receiving one of two lansoprazole-based therapies before and/or after therapy were investigated. Antibiotic susceptibility was determined by Etest. Genotyping was determined by cagA, babA, vacA and RAPD analyses. Target cells of internalization assay were AGS cells.

RESULTS

Five of six paired pre- and post-treatment isolates had the same predominant genetic profiles and exhibited similarly high internalization activities. The A2143G point mutation of the 23S rRNA gene conferred clarithromycin resistance. Moreover, increased antibiotic resistance after therapy was found for these five cases. Pre-treatment isolates from the failure group (n = 11) had higher level of internalization activity than those from the cure group (n = 31) (P = 0.00005). Antibiotic-resistant strains were significantly associated with higher internalization activity than were susceptible strains (metronidazole, P < 0.005; clarithromycin, P < 0.005).

CONCLUSIONS

Our results suggest that resistant H. pylori strains are associated with antibiotic resistance and superior internalization activity, protecting them against antibiotic treatment.

Lower prevalence of Helicobacter pylori infection with vacAs1a, cagA-positive, and babA2-positive genotype in erosive reflux esophagitis disease

BACKGROUND

Increased prevalence of esophagitis has been recognized in the West. Helicobacter pylori infection, particularly virulent strains, is proposed as a protective factor against the development of gastroesophageal reflux disease. To evaluate the relationship of reflux esophagitis with virulent H. pylori infection, we studied the prevalence of reflux esophagitis among H. pylori-infected and -uninfected patients and the genotype of isolates in Taiwan.

METHODS

Patients who had routine physical examination were investigated. The severity of esophagitis was evaluated using the Los Angeles grading system. H. pylori status was assessed by histology, rapid urease test, and bacterial culture. Genotyping of vacA, cagA, and babA2 was determined by polymerase chain reaction (PCR). Risk factors for severe esophagitis were evaluated.

RESULTS

Reflux esophagitis was found in 21.2% of 1622 patients. The prevalence of H. pylori infection was found in 33.0% of 276 patients with reflux esophagitis compared with 67.5% of 378 patients with normal esophagus (p < .001). Esophagitis occurred in a significantly lower rate among H. pylori-positive patients with peptic ulcer than those without peptic ulcer. cagA, babA2, and vacAs1a were detected in 100% of 143 isolates. Factors that predicted severe esophagitis included age, gender, and hiatus hernia but not H. pylori infection.

CONCLUSIONS

Our study suggests significantly lower incidence of H. pylori infection with the triple-positive virulent genotype in patients with reflux esophagitis in Taiwan.

An update on Helicobacter pylori microbiology and infection for the new millennium

The finding of the bacterium Helicobacter pylori in patients with symptomatic gastric diseases was a breakthrough for both treatment of peptic ulcer disease and studies of other infectious diseases. Helicobacter pylori infection is rare among the young, indicating that improved childhood living conditions have halted the transmission of the bacterium within families, with a parallel decrease in symptomatic gastroduodenal diseases. Extensive strain variation in H. pylori has been demonstrated at both the genomic and the protein level, and the interstrain variation is higher than in any other bacterium studied so far. Pathogenic markers in H. pylori and host genetics are both of importance for disease outcome. Genotypic or phenotypic markers of H. pylori strains may be used to discriminate patients who should undergo eradication therapy from those who might not benefit from it. Possible positive effects of the infection are still under investigation, and several hypotheses regarding the etiology of diseases in different parts of the stomach have been proposed. To be able to separate the disease-causing infections from the silent infections is a real challenge for the new millennium, and one of the most important issues for therapy and prevention, in the research field of H. pylori.

Helicobacter pylori virulence and genetic geography

Isolated for the first time in 1982 from human gastric biopsy, Helicobacter pylori is responsible for gastritis, peptic ulcer, and gastric cancer. A pathogenicity island acquired by horizontal transfer, coding for a type IV secretion system, is a major determinant of virulence. The infection is now treated with antibiotics, and vaccines are in preparation. The geographic distribution suggests coevolution of man and Helicobacter pylori.