Antibiotic resistance pattern and frequency of cagA and vacA genes in Helicobacter pylori strains isolated from patients in Tabriz city, Iran

Pyrosequencing analysis for rapid and accurate detection of clarithromycin resistance-associated mutations in Iranian Helicobacter pylori isolates

BACKGROUND

Treatment of Helicobacter pylori (H. pylori) infection has become challenging following the development of primary antibiotic resistance. A primary therapeutic regimen for H. pylori eradication includes clarithromycin; however, the presence of point mutations within the 23S rRNA sequence of H. pylori contributes to clarithromycin resistance and eradication failure. Thus, we aimed to develop a rapid and precise method to determine clarithromycin resistance-related point mutations using the pyrosequencing method.

METHODS AND RESULTS

H. pylori was isolated from 82 gastric biopsy samples and minimal inhibitory concentration (MIC) was evaluated using the agar dilution method. Clarithromycin resistance-associated point mutations were detected by Sanger sequencing, from which 11 isolates were chosen for pyrosequencing. Our results demonstrated a 43.9% (36/82) prevalence in resistance to clarithromycin. The A2143G mutation was detected in 8.3% (4/48) of H. pylori isolates followed by A2142G (6.2%), C2195T (4.1%), T2182C (4.1%), and C2288T (2%). Although the C2195T mutation was only detected by Sanger sequencing, the overall results from pyrosequencing and Sanger sequencing platforms were comparable.

CONCLUSIONS

Pyrosequencing could be used as a rapid and practical platform in clinical laboratories to determine the susceptibility profile of H. pylori isolates. This might pave the way for efficient H. pylori eradication upon detection.

Frequency of significant virulence genes in gastric biopsies of Helicobacter pylori-positive patients with gastritis

Helicobacter pylori is one of the most common bacteria affecting human societies worldwide, and is mainly associated with gastrointestinal complications due to different virulence factors. This study aimed to investigate some virulence genes of H. pylori in gastric biopsies of patients with gastritis in Sari city, North of Iran. Informed consent forms were obtained from the studied patients, and those who needed endoscopy were included in the study. To evaluate the prevalence of cagA, iceA1, iceA2, vacA, dupA, and oipA genes, gastric biopsies with positive or negative rapid urease test were collected from 50 patients (25 in each group) with gastro-duodenal diseases. The bacterial DNAs were extracted by a specific kit, and the presence of the genes was analyzed by PCR using specific primers. Eighteen (72%) biopsies from 25 H. pylori-positive samples were cagA-positive, while 17 (68%) biopsies contained the vacA gene, and 11 (44%) samples had both vacA and cagA genes. However, 16 (64%), 12 (48%), 13 (52%), and 14 (56%) biopsies contained dupA, iceA1, iceA2, and oipA genes, respectively. Due to the significant role of the studied virulence factors in the pathogenicity of H. pylori, the high prevalence of these factors in biopsies of patients with gastritis is a concern needing to the management in this region.

Detection of Helicobacter Pylori infection by invasive and non-invasive techniques in patients with gastrointestinal diseases from Iraq: A validation study

There is still no agreement on the gold standard technique for diagnosing of H. Pylori in Iraq, as well as a paucity of data on the validity of different diagnostic techniques. This study aimed to investigate the prevalence of this bacterium with different methods and compare them to the quantitative polymerase chain reaction (qPCR) as a golden standard technique among Iraqi patients. In total, 115 Iraqi patients strongly suspected of H. pylori infection were enrolled in the current study. Invasive techniques including rapid urease testing (RUT) and gastric tissue culture in addition to non-invasive techniques including 14C-Urea breath test (14C-UBT), stool antigen test (SAT), CagA-IgG serology, and qPCR were performed to confirm the H. pylori infection. The qPCR was used as the gold standard to estimate the sensitivity, specificity, positive and negative predictive values for the studied diagnostic tests. Overall, the prevalence rate of H. pylori in Iraqi patients was ranged from 47.8 to 70.4% using different methods. The positive results for each test were as follows: qPCR 81, (70.4%) UBT 79 (68.7%), SAT 77 (67%), RUT 76 (66.1%), Cag-IgG 61 (53%), and culture 55 (47.8%). The 14C-UBT showed the highest overall performance with 97.5% sensitivity, 97% specificity, and total accuracy of 97.3% followed by SAT, RUT, Cag-IgG, and culture method. Based on the accuracy of the studied methods for H. pylori detection, they can be arranged in order as follows: qPCR > UBT > SAT > RUT> CagA IgG > culture. Since a universal gold standard assay for the diagnosis of H. pylori has not yet been established in Iraq, the UBT may be recommended as first choice due to its higher performance compared to other methods.