Isolation and diagnosis of Helicobacter pylori by a new method: Microcapillary culture

AIM:To investigate the performance of the microcapillary culture method(MCM) in Helicobacter pylori(H.pylori) isolation and diagnosis.METHODS:Microcapillary culture(MC),classical culture(CC),rapid urease(CLO) test,and histopathologic examination(HE) were performed with biopsy samples.Homogenized biopsy samples were loaded into capillary tubes and incubated for 48 h at 37 ℃ without providing a microaerophilic environment.Additionally,three or four loops of the homogenized sample were inoculated in a ready-to-use selective medium(Becton Dickinson,Helicobacter Agar,Modified) specific for the isolation of H.pylori and incubated at 37 ℃ in a microaerophilic atmosphere provided by Campy Gen(Becton Dickinson,Gas Pack).Bacteria reproducing in microcapillary tubes were evaluated in an inverted microscope and also were evaluated after performing a CC with the content.Results obtained by CC,CLO test,and HE were compared with those of MC.The diagnostic performances of the methods used in this study were evaluated for specificity,sensitivity,positive predictive value(PPV),negative predictive value(NPV),and CI.RESULTS:H.pylori was found positive by CLO test +HE and/or CC culture in 26 patient antrum and corpus biopsy samples.In 25(25/26) patient biopsy samples,H.pylori was isolated by MCM,whereas in only 14(14/26) patient biopsy samples,H.pylori was isolatedby CC.CLO test and HE were found positive in 17(17/26) patient biopsy samples.Comparing the results of the isolation of H.pylori by MCM,CC,CLO test,and HE,the sensitivity of the MCM was found as 96%,the specificity as 80%,the PPV as 83%,the NPV as 95%,and the 95%CI as 0.76(χ2 =31.51,P < 0.01) whereas the sensitivity of the CC was found as 54%(χ2 =19.15,P < 0.01),and the sensitivity of the CLO test and HE were found as 65%(χ2 =25.26,P < 0.01).CONCLUSION:This new microcapillary cultivation method for H.pylori has high diagnostic sensitivity compared with CC,HE,and CLO tests.

Association between human leukocyte antigen gene polymorphisms and multiple EPIYA-C repeats in gastrointestinal disorders

BACKGROUND Polymorphisms of human leukocyte antigen(HLA)genes are suggested to increase the risk of gastric cancer(GC).AIM To investigate the HLA allele frequencies of patients with GC relative to a control group in terms of CagA+multiple(≥2)EPIYA-C repeats.METHODS The patient group comprised 94 patients[44 GC and 50 duodenal ulcer(DU)patients],and the control group comprised 86 individuals[(50 non-ulcer dyspepsia patients and 36 people with asymptomatic Helicobacter pylori(H.pylori)].Polymerase chain reaction was performed for the amplification of the H.pylori cagA gene and typing of EPIYA motifs.HLA sequence-specific oligonucleotide(SSO)typing was performed using Lifecodes SSO typing kits(HLA-A,HLA-B HLA-C,HLA-DRB1,and HLA-DQA1-B1 kits).RESULTS The comparison of GC cases in terms of CagA+multiple(≥2)EPIYA-C repeats showed that only the HLA-DQB1*06 allele[odds ratio(OR):0.37,P=0.036]was significantly lower,but significance was lost after correction(Pc=0.1845).The HLA-DQA1*01 allele had a high ratio in GC cases with multiple EPIYA-C repeats,but this was not significant in the univariate analysis.We compared allele frequencies in the DU cases alone and in GC and DU cases together using the same criterion,and none of the HLA alleles were significantly associated with GC or DU.Also,none of the alleles were detected as independent risk factors after the multivariate analysis.On the other hand,in a multivariate logistic regression with no discriminative criterion,HLA-DQA1*01(OR=1.848),HLA-DQB1*06(OR=1.821)and HLA-A*02(OR=1.579)alleles were detected as independent risk factors for GC and DU.CONCLUSION None of the HLA alleles were detected as independent risk factors in terms of CagA+multiple EPIYA-C repeats.However,HLA-DQA1*01,HLA-DQB1*0601,and HLA-A*2 were independent risk factors with no criterion in the multivariate analysis.We suggest that the association of these alleles with gastric malignancies is not specifically related to cagA and multiple EPIYA C repeats.