[Detection of Helicobacter pylori and antimicrobial resistance in gastric biopsy specimens].

Helicobacter pylori is reported as the etiological agent of gastritis, gastric and duodenal ulcer, gastric adenoid carcinoma and mucosa-associated lymphoid tissue lymphoma. In the diagnosis of H.pylori infections invasive (culture, histopathological examination, rapid urease test and molecular tests) and non-invasive (urea breath test, serological tests, stool culture and stool antigen/nucleic acid tests) methods may be used. Clarithromycin, amoxicillin and combination of metronidazole and protonpump inhibitor or ranitidine bismuth citrate triple treatment protocol is applied in order to treat and eradicate the infection. However, increasing rates of antibiotic resistance among H.pylori strains reduces the success of eradication therapy. The aim of this study was to investigate the presence of H.pylori in the gastric antral biopsy specimens and to determine the antimicrobial resistance of the isolates. A total of 149 gastric antral biopsy specimens obtained from patients (age range: 17-83 years; 73 were male) who admitted to Mersin University Faculty of Medicine Department of Internal Medicine Gastroenterology clinic with dyspeptic complaints were included in the study. H.pylori presence was investigated by culture, polymerase chain reaction (PCR) and urease test from gastric biopsy specimens, and H.pylori-specific antigen (HpSA) was investigated by ELISA in the stool samples of patients. Resistance to tetracycline, amoxicillin, metronidazole and levofloxacin was determined with E-test method. Clarithromycin resistance was determined both by E-test and PCR-RFLP (restriction fragment length polymorphism) methods. H.pylori was detected in 29.6% (43/145) of patients with culture, 55.2% (80/145) of patients with urease test, 57% (65/114) of patients with HpSA test and 71.3% (102/143) of patients with PCR. The sensitivity and specificity of culture, PCR, HpSA and urease tests were determined as 52.4% and 100%, 96.3% and 62.3%, 80.3% and 81.4%, 86.6% and 85.7%, respectively. According to the E-test results, resistance to clarithromycin was 18.2%, to tetracycline 9.1%, to metronidazole 45.5%, to levofloxacin 18.2% and no resistance was determined to amoxicillin. Clarithromycin resistance was searched in 94 of PCR positive 102 samples, and 17 (18.1%) of them yielded clarithromycin resistance. Of them 11 (64.7%) harbored A2144G (at 2144. nucleotide), and 6 (%35.3) harbored A2143G (at 2143. nucleotide) point mutations. In our study, PCR was determined as the most sensitive method, however due to its low specificity, the results should be confirmed with at least one of the other methods. The specificity of culture method was high, but sensitivity was found to be quite low compared with other methods. The sensitivity and specificity of urease and HpSA tests were found to be similar. In conclusion, in cases which endoscopy could not be done, non-invasive, rapid and practical HpSA method can be used in diagnosis and monitorization of the treatment. In the case of treatment failure, culture should be performed for antibiotic susceptibility testing of the isolate.