The Relationship Between Helicobacter Pylori Antibiotic Resistance And Virulence Gene In Children

Objective: To evaluate the prevalence of clarithromycin 、amoxicillin and metronidazole resistance of Helicobacter pylori clinical isolates and the expression of virulence genes cag A and vac A in children and to investigate whether there is any relationship between drug resistance and genotype in this study.Methods: Hp strains clinical isolates were cultured from children patients(500) with upper abdominal discomfort who underwent gastroscopy during the period from January 2014 to December 2014 in Children’s Hospital of Guiyang City,rapid urease test was applied to the antrum of stomach mucosal tissue incised under gastroscope.The distribution of cag A and vac A was detected by polymerase chain reaction, and the resistance to clarithromycin 、 amoxicillin and metronidazole were detected by agar dilution methodin. Fisher exact test statistics was using to analyse the experimental data.Results:1.In 500 children with gastroscopy randomly selected,through rapid urease test to determine the helicobacter pylori infection in children with 281 cases of helicobacter pylori infection rate was 56.2%(281/500); 31 strains of H.pylori were isolated and cultured from gastric mucosa;The positive of H.pylori rate was 11.03%(31/281).2.Among the 31 Hp strains clinical isolates from children,there were 6,5 and13 strains were resistant to clarithromycinm,amoxicillin and metronidazole and the resistant rate was 19.35%(6/31),16.13%(6/31), 41.94%(13/31),respectively. No relationship was found between antibiotics and gender(P>0.05),as well as different diseases(P>0.05).3.The positive rate of cag A was 83.87% in this aera.The positive rate of vac A was 100%.Of those31 specimens, 83.87%,0%,19.35%,12.90%and74.19%(19/31)carried vac As1 a, vac As1 b, vac As1c、vac Am1, and vac Am2, respectively.The rate of different genenotype was s1a/m2 48.39%( 15/31), s1a+s1c/m2 12.90%(4/31),s1 a 12.90%(4/31),s1c/m26.45%(2/31),s1a/m1 6.45%(2/31),m1 3.23%(1/31)and m2 6.45%(2/31).One Hp strain carried both m1 and m2. 4 cases were not detected in signal sequence.4.No correlation was found between cag A gene and vac A gene and clarithromycin,amoxicillin and metronidazole resistance(P>0.05).Conclusion: 1.The high rate of Helicobacter pylori infection in children in the experimental group was 56.2%.2.The resistant rate of clarithromycin 、amoxicillin and metronidazole was 19.35%(6/31),16.13%(6/31) and 41.94%(13/31),respectively.We should pay more attention to metronidazole because of the high antibotic resistance rate.we can use the standard triple therapy for eradication of Helicobacter pylori,because the resistance rate of clarithromycin was less than 20%.Amoxicillin resistance rate was low than other drugs, so it could be used as the preferred drug of eradication treatment wiith Hp.3.The dominant genotype was cag A+ and vac As1/m2.4.There was no relationship between the resistance to clarithromycin,amoxicillin and metronidazole and vacuolating cytotoxin and cytotoxin associated gene.