[Detection of Helicobacter pylori by immunoblot: a multiple-center study]

To evaluate the accuracy and effectiveness of Helicobacter pylori(H.pylori)antibody detection kit (immunoblot) in typing H. pylori strains, and to investigate the relationship between characteristics of H. pylori strains and clinical outcomes.

A total of 378 patients with upper gastrointestinal symptoms who had received gastroscopy and had pathological results within the period from March to August 2012 were collected from 6 centers in China.In all the patients, H. pylori antibody detection kit was used to detect and type serum H. pylori antibodies.The sensitivity, specificity, and accuracy of immunoblot in diagnosing H. pylori infection were evaluation in comparison to (13)C urea breath test (UBT) as the"gold standard". The results were also compared with those colloidal gold method.The relationship between H. pylori typing and clinical conditions was analyzed.

Totally 378 patients were enrolled, in which 257 had H. pylori-positive (13)C UBT results, and 121 were negative.With (13)C UBT as the"gold standard", the sensitivity, specificity, positive predictive value, negative predictive value, and concordance rate of H. pylori antibodies detection kit(immunoblot)were 97.7%, 86.8%, 94.0%, 94.6%, and 94.2%, respectively; the sensitivity, specificity, positive predictive value, negative predictive value, and concordance rate of colloidal gold method were 84.4%, 92.6%, 96.0%, 73.7%, and 87.0%, respectively.In patients diagnosed as H. pylori-positive by (13)C UBT and immunoblot, 93.0%(53/57) in H. pylori eradication failure patients and 93.8%(182/194)in untreated patients were infected with type Ⅰ H. pylori as detected by immunoblot, with no statistically significant difference (P=0.764). The type Ⅰ strains positive rate was 94.2%(65/69), 89.9%(62/69)and 98.2% (55/56) in non-atrophy gastritis, atrophy gastritis, and duodenal ulcer untreated patients, respectively, the positive rate of type Ⅰ strains higher in duodenal ulcer cases than in gastritis ones, but with no statistically significant difference(P=0.185).

Compared with the"gold standard"(13)C UBT, the accuracy of H. pylori antibody detection kit (immunoblot) and that of colloidal gold method are both fairly high.Different H. pylori strains may have significantly different potential in causing diseases, as typeⅠtrain appeared to be more virulent than type Ⅱ strain, especially in causing peptic ulcer.There was no obvious difference between eradication failure and untreated patients in terms of positive rate of type Ⅰ H. pylori strains, hence further study is needed to explore the relationship between type Ⅰ H. pylori and eradication rates.