Transcriptional analysis of Helicobacter pylori cytotoxic-associated gene-pathogenicity island in response to different pH levels and proton pump inhibitor exposure

BACKGROUND

Long-term use of proton pump inhibitors (PPIs) can increase the risk of gastric cancer in Helicobacter pylori-infected patients; nevertheless, there is no data about their impact on the pathogenicity of H. pylori. This study aimed at investigating the transcriptional alteration of key gene mediators of cytotoxin-associated gene-pathogenicity island (cag-PAI) among clinical H. pylori isolates in response to omeprazole at different pH levels.

METHODS

Accordingly, H. pylori isolates with the same virulence genotypes selected from the gastric biopsies of patients and transcriptional alteration in the cag-PAI genes studied in the presence or absence of omeprazole (2 mg/mL) at pH 2.0, 4.0 and 7.0 after 30 and 90 minutes of the treatment. Relative changes in the transcriptional levels were recorded in each assay, separately.

RESULTS

Of 18 H. pylori isolates, the cag-PAI empty site was detected in four strains, while the presence of cagA, cagL and cagY was characterized in 77.7%, 83.3% and 83.3% of the cag-PAI-positive strains, respectively. Transcriptional analysis of the selected strains showed up-regulation of cagA and cagL, mainly at pH 2.0 and 4.0 after 30 and 90-minute exposure. A diversity in the expression levels of cag-PAI genes was seen among the strains at the extent and time of induction.

CONCLUSION

Our results showed that omeprazole could increase the expression of H. pylori cagA and cagL at acidic pH. Heterogeneity among the strains probably has an impact on the extent of their interplay with PPIs. Further studies are needed to establish this correlation.

The increasing antimicrobial resistance of Helicobacter pylori in Iran: A systematic review and meta-analysis

BACKGROUND

Antimicrobial resistance of Helicobacter pylori can result in eradication failure. Metadata on the antimicrobial resistance of H pylori in Iran could help to formulate H pylori eradication strategies in Iran.

METHODS

A systematic review was performed after searching in MEDLINE, Scopus, Embase, Web of Science, and the Cochrane Library. A meta-analysis was performed, and a comparison of the rates between children and adults; time periods (1999-2010, 2011-2016, 2017-2019); and the methods used was carried out.

RESULTS

A total of 66 studies investigating 5936 H pylori isolates were analyzed. The weighted pooled resistance (WPR) rates were as follows: clarithromycin 21% (95% CI 16-26), metronidazole 62% (95% 57-67), clarithromycin in combination with metronidazole 16% (95% CI 10-23), ciprofloxacin 24% (95% CI 15-33), levofloxacin 18% (95% CI 9-30), erythromycin 29% (95% CI 12-50), furazolidone 13% (95% CI 4-27), tetracycline 8% (95% CI 5-13), and amoxicillin 15% (95% CI 9-22). During the three time periods, there was an increased resistance to amoxicillin, clarithromycin, ciprofloxacin, furazolidone, and tetracycline (P ˂ .05). Furazolidone and a clarithromycin/metronidazole combination had the higher resistance rates in children (P ˂ .05).

CONCLUSION

An increasing rate of resistance to amoxicillin, clarithromycin, ciprofloxacin, furazolidone, and tetracycline in Iranian H pylori isolates was identified. In children, the resistance to furazolidone and a combination of clarithromycin and metronidazole is higher compared to adults. As a stable, high resistance to metronidazole was found in children and adults in all Iranian provinces, we suggest that metronidazole should not be included in the Iranian H pylori eradication scheme.

An Updated Systematic Review and Meta-Analysis on the Helicobacter pylori Antibiotic Resistance in Iran (2010-2020)

This updated systematic review and meta-analysis followed two objectives: (1) to determine Helicobacter pylori antibiotic resistance in Iran during 2010-2020 and (2) to assess the trend of resistance from 1997 to 2020. A systematic search in multiple databases, including ISI Web of Knowledge, PubMed, Scopus, Google Scholar, and the Scientific Information Database (SID), was performed using MeSH-extracted keywords. Meta-analysis was done on extracted data from a total of 27 included citations published between 2010 and January 20, 2020. The overall mean prevalence of H. pylori resistance was 64.9% for metronidazole, 25.3% for clarithromycin, 20.7% for amoxicillin, 16.1% for tetracycline, 21.9% for levofloxacin, 22.8% for rifampicin, 27.2% for furazolidone, 32.3% for ciprofloxacin, and 38.7% for erythromycin. In addition, the prevalence of multidrug-resistant strains of H. pylori was 26.5% in Iran. The pooled prevalence of point mutations A2143G, A2142G, and A2142C associated with clarithromycin resistance were 46.6%, 37.2%, and 5.5%, respectively; mutations in frxA and rdxA genes associated with metronidazole resistance were 46.4% and 19.7%, respectively; gyrA and gyrB genes mutations among fluoroquinolone-resistant strains were 55.3% and 48.2%, respectively; and resistance associated with integrons was 47%. According to the present findings, resistance of H. pylori to antibiotics used for eradication therapy has reached an alarming level in Iran. Furthermore, the trend of H. pylori resistance has increased between 1997 and 2020. Hence, continuous surveillance on resistance patterns, logical prescription and appropriate consumption of antibiotics, and selecting effective therapeutic regimens in accordance with local resistance patterns are required to prevent further spread of resistance and ensuing treatment failures.

Histological changes in refractory Helicobacter pylori infection and its relationship with increased levels of resistance to antibiotics and therapeutic regimens: one-year follow-up

Eradication failure of Helicobacter pylori infection could play a causal role in progression of gastric disorders. In this study, infection with H. pylori was followed in gastric biopsies of symptomatic adult patients at two phases during 1-year period. Analyses were done to show association of therapeutic regimens with the refractory infection, changes in sequence types (STs) and minimum inhibitory concentration (MIC) values, and progression of histopathological changes. Infection with H. pylori was confirmed in 32.3% (57/170) of the patients. Persistent infection with H. pylori was confirmed in 14 out of the 25 patients (56%) who participated at the second phase of the study. A difference between primary and secondary resistance rates to clarithromycin (49% vs 64.3%), metronidazole (76.36% vs 100%), and ciprofloxacin (45% vs 57.1%) was detected. Although the re-emerged strains in patients with refractory infection did not show alteration in STs, their MIC₅₀ values showed twofold increases for clarithromycin and ciprofloxacin. While ciprofloxacin containing regimens were more successful, failure of metronidazole containing regimens was detected in 77% of the patients. Consequently, inappropriate medication has an impact on refractory H. pylori infection, which could cause to a rise in resistance levels to antibiotics and progression of pathological disorders.