The State of the Art of Molecular Fecal Investigations for Helicobacter pylori (H. pylori) Antibiotic Resistances

Helicobacter pylori Secondary Antibiotic Resistance after One or More Eradication Failure: A Genotypic Stool Analysis Study

Helicobacter pylori (H. pylori) antibiotic resistance is the leading cause for unsuccessful eradication therapy. After one or more failures, the chance of encountering secondary antibiotic resistance increases. The aim of this study was to characterize genotypic secondary resistance in a cohort of southern Italian H. pylori patients with at least one previous failure. Such patients collected stool samples using a dedicated kit (THD fecal testTM), and bacterial DNA was extracted and amplified using RT-PCR. Resistance to clarithromycin, amoxicillin, metronidazole, levofloxacin, and tetracycline was assessed using a high-resolution melting curve. We enrolled 50 patients. A total of 72% of patients failed one previous antibiotic course, 16% failed two, 10% failed three, and 2% failed four. The rate of secondary antibiotic resistance was 16% for clarithromycin, 18% for metronidazole, 14% for amoxicillin, 14% for levofloxacin, and 2% for tetracycline. Among the eight clarithromycin-resistant patients, five (62.5%) previously received a clarithromycin-based regimen. The same rate was 33.3% (3/9) for metronidazole. The only tetracycline-resistant patient had received Pylera. In conclusion, our data seem to show that, even though secondary resistance is not very high, resistance to clarithromycin could be very likely related to previous exposure to this antibiotic.

Testing for Helicobacter pylori in an era of antimicrobial resistance

Antimicrobial resistance in Helicobacter pylori has reached alarming levels and is compromising traditional empiric treatment of H. pylori. Antimicrobial susceptibility testing is routinely performed for infectious diseases when there is a risk of resistance and is now recommended to guide therapy for H. pylori. This mini-review overviews the current diagnostics for H. pylori with a focus on tests that enable susceptibility-guided treatment, including molecular tests performed directly on stool and endoscopically collected specimens.

Helicobacter pylori Antibiotic Resistance: Molecular Basis and Diagnostic Methods

Helicobacter pylori is one of the most common cause of human infections. Infected patients develop chronic active gastritis in all cases, which can lead to peptic ulcer, atrophic gastritis, gastric cancer and gastric MALT-lymphoma. The prevalence of H. pylori infection in the population has regional characteristics and can reach 80%. Constantly increasing antibiotic resistance of H. pylori is a major cause of treatment failure and a major problem. According to the VI Maastricht Consensus, two main strategies for choosing eradication therapy are recommended: individualized based on evaluating sensitivity to antibacterial drugs (phenotypic or molecular genetic method) prior to their appointment, and empirical, which takes into account data on local H. pylori resistance to clarithromycin and monitoring effectiveness schemes in the region. Therefore, the determination of H. pylori resistance to antibiotics, especially clarithromycin, prior to choosing therapeutic strategy is extremely important for the implementation of these treatment regimens.

Helicobacter pylori infection

Helicobacter pylori infection causes chronic gastritis, which can progress to severe gastroduodenal pathologies, including peptic ulcer, gastric cancer and gastric mucosa-associated lymphoid tissue lymphoma. H. pylori is usually transmitted in childhood and persists for life if untreated. The infection affects around half of the population in the world but prevalence varies according to location and sanitation standards. H. pylori has unique properties to colonize gastric epithelium in an acidic environment. The pathophysiology of H. pylori infection is dependent on complex bacterial virulence mechanisms and their interaction with the host immune system and environmental factors, resulting in distinct gastritis phenotypes that determine possible progression to different gastroduodenal pathologies. The causative role of H. pylori infection in gastric cancer development presents the opportunity for preventive screen-and-treat strategies. Invasive, endoscopy-based and non-invasive methods, including breath, stool and serological tests, are used in the diagnosis of H. pylori infection. Their use depends on the specific individual patient history and local availability. H. pylori treatment consists of a strong acid suppressant in various combinations with antibiotics and/or bismuth. The dramatic increase in resistance to key antibiotics used in H. pylori eradication demands antibiotic susceptibility testing, surveillance of resistance and antibiotic stewardship.