Antimicrobial effectiveness of ketoconazole against metronidazole-resistant Helicobacter pylori isolates from Iranian dyspeptic patients

Consumption of non-antibacterial drugs may have negative impact on Helicobacter pylori colonization in the stomach

Background

Nineteen non-antibacterials were examined to show that their consumption for treatment of other diseases may inhibit Helicobacter pylori. Four antibiotics were used for comparison.

Materials and methods

Agar dilution method was used to examine the susceptibility of 20 H. pylori isolates to 4 antibiotics; metronidazole (MTZ), clarithromycin (CLR), amoxicillin (AMX), tetracycline (TET) and 19 non-antibacterials; proton pump inhibitors (PPIs), H2-blockers, bismuth subsalicylate (BSS), antifungals, statins, acetaminophen (ACE), aspirin (ASA), B-vitamins (B-Vits; Vit B1, Vit B6 and Vit Bcomplex) and vitamin C (Vit C). Blood agar plates were prepared with different concentrations of drugs and spot-inoculated with bacterial suspensions. Plates were incubated at 37 °C under microaerobic conditions and examined after 3-5 days. The isolate #20 that was mucoid and resistant to 19 drugs, including MTZ and SMV was tested against combined MTZ (8 μg/mL) and SMV (100 μg/mL). Results were analyzed statistically.

Results

Minimum inhibitory concentrations (MICs, μg/mL) of drugs and the frequency of susceptible H. pylori were determined as MTZ (8, 80%), CLR (2, 90%), AMX (1, 100%), TET (0.5, 70%), PPIs (8-128, 80%), H2-blockers (2000-8000, 75-80%), BSS (15, 85%), antifungals (64-256, 30-80%), statins (100-250, 35-90%), ACE (40, 75%), ASA (800, 75%), B-Vits (5000-20000, 80-100%) and Vit C (2048, 85%). Susceptibility of H. pylori isolates to 16 out of 19 non-antimicrobials (75-100%) was almost similar to those of antibiotics (70-100%) (P-value >0.05). The highest susceptibility rate (100%) belonged to Vit B1, Vit B6 and AMX. Out of 20 H. pylori isolates, 17 (85%) were susceptible to ≥13 non-antimicrobials and 3 (15%) were susceptible to < 13 (P-value <0.05). Mucoid H. pylori showed susceptibility to combination of MTZ and SMV.

Conclusions

Most of non-antibacterials inhibited H. pylori isolates, similar to antibiotics but their MICs exceeded those of antibiotics and their plasma concentrations. At low plasma concentration, non-antimicrobials may act as weak antibacterials, antibiotic adjuvants and immunostimulators.

In Search for Reasons behind Helicobacter pylori Eradication Failure–Assessment of the Antibiotics Resistance Rate and Co-Existence of Helicobacter pylori with Candida Species

Helicobacter pylori eradication is characterized by decreasing successful eradication rates. Although treatment failure is primarily associated with resistance to antibiotics, other unknown factors may influence the eradication outcome. This study aimed to assess the presence of the antibiotics resistance genes in H. pylori and the presence of Candida spp., which are proposed to be endosymbiotic hosts of H. pylori, in gastric biopsies of H. pylori-positive patients while simultaneously assessing their relationship. The detection and identification of Candida yeasts and the detection of mutations specific for clarithromycin and fluoroquinolones were performed by using the real-time PCR (RT-PCR) method on DNA extracted from 110 gastric biopsy samples of H. pylori-positive participants. Resistance rate to clarithromycin and fluoroquinolone was 52% and 47%, respectively. Antibiotic resistance was associated with more eradication attempts (p < 0.05). Candida species were detected in nine (8.18%) patients. Candida presence was associated with older age (p < 0.05). A high rate of antibiotic resistance was observed, while Candida presence was scarce, suggesting that endosymbiosis between H. pylori and Candida may not be a major contributing factor to the eradication failure. However, the older age favored Candida gastric mucosa colonization, which could contribute to gastric pathologies and microbiome dysbiosis.

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.