Rates of resistance to clarithromycin among Helicobacter pylori isolates in the United States and Europe are high enough to warrant discontinuation of empiric use of proton pump inhibitor (PPI)–based triple therapy that includes the antibiotic in these regions, a new study has found.
Overall, 22.2% of participants were resistant to clarithromycin – a rate that is above the currently recommended threshold of 15% or higher for avoidance of PPI-based triple therapy that includes clarithromycin.
, study investigator William Chey, MD, professor and chief, Division of Gastroenterology and Hepatology, Michigan Medicine, Ann Arbor, said in an interview.
Judith Kim, MD, a gastroenterologist at NYU Langone Health and clinical instructor of medicine at NYU Grossman School of Medicine, who wasn’t involved in the study, agrees.
“The use of PPI-based triple therapy is still common practice despite recent recommendations to avoid clarithromycin in areas with high resistance rates,” Dr. Kim told this news organization.
“This study shows that multiple parts of the United States and Europe have high resistance rates,” rendering clarithromycin-based regimens “more likely to ineffectively eradicate H pylori,” Dr. Kim said.
The study was published online in The American Journal of Gastroenterology.
Better options now available
Guidelines advise against the use of PPI-based triple regimens with clarithromycin for H. pylori infection in areas where resistance is 15% or higher or for patients who have previously received macrolides. However, up-to-date information on H. pylori antimicrobial resistance patterns is limited, especially in the United States.
Dr. Chey and colleagues assessed resistance rates to antibiotics commonly used to treat H. pylori in isolates from 907 adults with the infection in the United States and Europe. They included four U.S. subregions and five participating European countries.
In all U.S. subregions and European countries, clarithromycin resistance rates were above 15% except possibly in the United Kingdom, where the sample size was too small to provide a reliable estimate.
Three-quarters of the clarithromycin-resistant isolates were also resistant to metronidazole.
The study also found that, overall, 1.2% of patients had isolates that were resistant to amoxicillin, and 69.2% had isolates resistant to metronidazole. Resistance patterns were similar in the United States and Europe; metronidazole resistance was the most common (50%-79% of isolates), and amoxicillin was the least common (≤ 5%).
“Overall, these data provide robust evidence to support a shift away from the default empiric prescription of triple combinations containing a PPI and clarithromycin for H. pylori infection in the United States and Europe,” the study team writes.
The high prevalence of resistance, including dual resistance, highlights the need for antibiotic stewardship and resistance surveillance, as well as novel treatment strategies for H. pylori infection, they add.
Last spring, as previously reported, the United States Food and Drug Administration approved two vonoprazan-based treatments for H. pylori: Voquezna Triple Pak (vonoprazan, amoxicillin, clarithromycin) and Voquezna Dual Pak (vonoprazan, amoxicillin), both from Phathom Pharmaceuticals.
“Vonoprazan-based treatment may be superior to standard PPI triple therapy for clarithromycin-resistant infections based on prior studies and is a potential good option,” Dr. Kim said.
Still, she added, she “would most likely first recommend regimens that do not have clarithromycin, such as bismuth quadruple therapy.”