Editorial

Molecular-based Helicobacter pylori Susceptibility Testing Is Almost Ready for Prime Time

The epitope vaccine against four virulence proteins (FVpE) from Helicobacter pylori (H. pylori) was expressed and purified. Western blot and Enzyme-linked Immunosorbent Assays (ELISA) were used to identify and investigate the immunoreactivity of FVpE protein. The immune-sensing platform based on titanium carbide/colloidal gold nanoparticles@carbon nanofiber/ionic liquid composites electrode was constructed for immobilizing FVpE. Electrochemical impedance spectroscopy (EIS) was used to study the electrochemical properties of the modified electrodes. The relevant influenced factors were optimized including pH value, antigen concentration, and incubating time. The prepared H. pylori label-free electrochemical immunosensor was used for antibody detection using differential pulse voltammetry (DPV). Under the optimal experimental conditions, the linear ranges of H. pylori antibodies, including anti-H. pylori, cytotoxin-associated gene A (CagA), vacuolating cytotoxin-associated gene A (VacA), and urease A (UreA), were all 0.1–5 ng mL⁻¹, except urease B (UreB, 0.1–4.5 ng mL⁻¹). The selectivity study showed that other antibodies had little influence on the detection of H. pylori antibodies. The immunosensor could be used to detect serum samples, and the recoveries were in the range of 68.5%–100.5%.

La infección por Helicobacter pylori es la enfermedad infecto-contagiosa más diseminada a nivel mundial, alcanzando una prevalencia del 50-80% en países en vías de desarrollo. La infección crónica es considerada como la principal causa de gastritis crónica, y se ha relacionado con otras enfermedades como úlcera péptica, linfoma de tejido linfoide asociado a mucosa gástrica y cáncer gástrico. El tratamiento más común son los esquemas de erradicación que utilizan tres o cuatros fármacos, entre ellos un inhibidor de la bomba de protones (IBP) y dos antibióticos, claritromicina y amoxicilina o metronidazol. El uso empírico de antibióticos para la erradicación de la bacteria ha propiciado una creciente resistencia a dichos fármacos, disminuyendo la eficacia de los esquemas y aumentando los costos para el paciente y para el sector salud. Es por esto que el desarrollo de métodos moleculares no invasivos de siguiente generación promete ser una herramienta que revolucione la terapéutica en H. pylori. La detección genotípica y fenotípica de resistencia a antibióticos de la bacteria permite brindar esquemas personalizados de tratamiento, disminuir costos e implementar un programa de administración de antibióticos.

Los objetivos de esta revisión narrativa son analizar y comparar los métodos diagnósticos tradicionales y de siguiente generación para el diagnóstico de H. pylori, explicar los diversos factores asociados a falla de erradicación y puntualizar sobre el impacto de la creciente resistencia a antibióticos sobre la reversión y la prevención de enfermedades asociados a H. pylori.

Helicobacter pylori infection is the most widespread infectious-contagious disease worldwide, reaching a prevalence of 50-80% in developing countries. Chronic infection is considered the main cause of chronic gastritis and has been related to other diseases, such as peptic ulcer, gastric mucosa-associated lymphoid tissue lymphoma, and gastric cancer. The most common treatment is with eradication regimens that utilize three or four drugs, including a proton pump inhibitor (PPI) and the antibiotics, clarithromycin and amoxycillin or metronidazole. Empiric antibiotic use for eradicating the bacterium has led to a growing resistance to those drugs, reducing regimen efficacy and increasing costs for both the patient and the healthcare sector. In such a context, the development of noninvasive next-generation molecular methods holds the promise of revolutionizing the treatment of H. pylori. The genotypic and phenotypic detection of the resistance of the bacterium to antibiotics enables personalized treatment regimens to be provided, reducing costs and implementing an antibiotic stewardship program.

The aims of the present narrative review were to analyze and compare the traditional and next-generation methods for diagnosing H. pylori, explain the different factors associated with eradication failure, and emphasize the impact of the increasing antibiotic resistance on the reversal and prevention of H. pylori-associated diseases.

We provide a primer to assist in the difficult transition of Helicobacter pylori therapy guidelines to those that adhere to the principles of antimicrobial stewardship. This transition will entail abandonment of many of the principles that heretofore formed the basis of treatment guidelines and recommendations. The goals of antimicrobial stewardship include optimization of the use of antibiotics while reducing antimicrobial resistance. The critical outcome measure is absolute cure rate which largely restricts comparative trials to those which reliably produce high cure rates (eg, ∼95%). Therapies that fail to achieve at least a 90% cure rate should be abandoned as unacceptable. Because only optimized therapies should be prescribed, guidance on the principles and practices of optimization will we required. Therapies that contain antibiotics which do not contribute to outcome should be eliminated. Surveillance, one of the fundamental elements of antimicrobial stewardship, must be done to provide ongoing assurance that the recommended therapies remain effective. It is yet not widely recognized when utilizing otherwise highly successful therapies, the routine test of cure data is an indirect, surrogate method for susceptibility testing. To systematically guide therapy, test of cure data should be collected, shared and integrated into local antimicrobial stewardship programs to provide guidance regarding best practices to both prescribers and public health individuals. Treatment recommendations should be compatible with those of the American Society of Infectious Disease white paper on the conduct of superiority and organism-specific clinical trials of antibacterial agents for the treatment of infections caused by drug-resistant bacterial pathogens which include criteria for ethical active-controlled superiority studies of antibacterial agents.

The decline in Helicobacter pylori cure rates emphasizes the need for readily available methods to determine antimicrobial susceptibility. Our aim was to compare targeted next-generation sequencing (NGS) and culture-based H pylori susceptibility testing using clinical isolates and paired formalin-fixed, paraffin-embedded (FFPE) gastric biopsies.

H pylori isolates and FFPE tissues were tested for susceptibility to amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and rifabutin using agar dilution and NGS targeted to 23S rRNA, gyrA, 16S rRNA, pbp1, rpoB and rdxA. Agreement was quantified using κ statistics.

Paired comparisons included 170 isolates and FFPE tissue for amoxicillin, clarithromycin, metronidazole, and rifabutin and 57 isolates and FFPE tissue for levofloxacin and tetracycline. Agreement between agar dilution and NGS from culture isolates was very good for clarithromycin (κ = 0.90012), good for levofloxacin (κ = 0.78161) and fair for metronidazole (κ = 0.55880), and amoxicillin (κ = 0.21400). Only 1 isolate was resistant to tetracycline (culture) and 1 to rifabutin (NGS). Comparison of NGS from tissue blocks and agar dilution from isolates from the same stomachs demonstrated good accuracy to predict resistance for clarithromycin (94.1%), amoxicillin (95.9%), metronidazole (77%), levofloxacin (87.7%), and tetracycline (98.2%). Lack of resistance precluded comparisons for tetracycline and rifabutin.

Compared with agar dilution, NGS reliably determined resistance to clarithromycin, levofloxacin, rifabutin, and tetracycline from clinical isolates and formalin-fixed gastric tissue. Consistency was fair for metronidazole and amoxicillin. Culture-based testing can predict treatment outcomes with clarithromycin and levofloxacin. Studies are needed to compare the relative ability of both methods to predict treatment outcomes for other antibiotics.