Metronidazole Is Failing H. pylori Treatment in Latin America
Source: michaelll via Flickr.
Highlights
- Metronidazole Resistance Is Undermining Standard H. pylori Therapy
- Colombian Genomic Studies Reveal Extremely High Resistance Rates
- Resistance Across Peru and Brazil Exceeds Safe Empiric Thresholds
- Continued Reliance on Metronidazole Puts Patients at Risk
Helicobacter pylori (H.pylori) is a highly prevalent stomach-colonizing bacterium associated with gastritis, peptic ulcer disease, fatty liver disease, and gastric cancer.
Growing evidence also links H. pylori infection to extraintestinal conditions, including iron-deficiency anemia and vitamin B12 deficiency.
Globally, H. pylori infect about half the population, with prevalence exceeding 80% in many developing regions like Latin America.
The standard H. pylori treatment therapy includes proton pump inhibitor plus two or more antibiotics.
Although this eradication therapy is widely used, rising antimicrobial resistance has become the main reason treatment fails, especially when it comes to metronidazole.
This article examines how metronidazole resistance is undermining its effectiveness as a first-line H. pylori treatment across Latin America.
High Metronidazole Resistance in Colombia’s H. pylori Strains
Source: Pedro Szekely via Flickr.
In a genomic epidemiology study by Muñoz et al., researchers analyzed H. pylori isolates from Colombia to identify genetic mutations associated with antibiotic resistance.
The analysis focused on metronidazole resistance, examining well-established H. pylori resistance genes rdxA and frxA, which play a central role in treatment failure.
They found that a very high proportion (75.7%) of the 221 genomes analyzed harbored mutations associated with metronidazole resistance, predominantly in the rdxA gene.
The high frequency of metronidazole-related mutations underscores the significant prevalence of metronidazole resistance in Colombian H. pylori strains. In turn, this prevalence has negative implications for treatment effectiveness in this region.
In a similar fashion, the study by Mannion et al. found that nearly all H. pylori strains isolated from gastric cancer patients in two Colombian regions were resistant to metronidazole, highlighting the widespread nature of antibiotic resistance.
High Metronidazole Resistance in H. pylori Across Peru and Brazil
Source: Elias Rovielo via Flickr.
A large systematic review and meta-analysis by Savoldi et al. demonstrated that metronidazole resistance in H. pylori is widespread worldwide, with pooled primary resistance rates exceeding 15% across all World Health Organization regions.
The analysis included 178 studies encompassing 66,142 H. pylori isolates from 65 countries, making it one of the most comprehensive global assessments of antibiotic resistance to date.
In the Americas region, metronidazole resistance rates approached 10%, identifying it as one of the most prevalent resistance patterns contributing to eradication failure.
Importantly, data from Latin America reveal substantially higher resistance levels.
Clinical isolates from Peru showed metronidazole resistance rates of approximately 62%, while Brazil reported rates near 40%.
These values far exceed empiric treatment thresholds and underscore the urgent need for local antibiotic resistance surveillance to guide effective H. pylori eradication strategies.
Why This Matters
Gastritis due to H. pylori. Source: Patho via Wikimedia Commons.
Metronidazole remains a cornerstone of first-line and rescue Helicobacter pylori treatment across much of Latin America.
Yet, resistance rates in Latin American countries like Colombia, Peru, and Brazil are far above the thresholds where empiric use is considered effective.
In regions where access to susceptibility testing is limited and antibiotics are frequently available over the counter, continued reliance on metronidazole without local resistance data risks amplifying multidrug resistance rather than eradicating infection.
These data underscore the urgent need for region-specific H. pylori treatment guidelines and routine antibiotic resistance surveillance.
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